1.
Walt Disney Concert Hall
–
The Walt Disney Concert Hall at 111 South Grand Avenue in Downtown of Los Angeles, California, is the fourth hall of the Los Angeles Music Center and was designed by Frank Gehry. It opened on October 24,2003, the hall is a compromise between an arena seating configuration, like the Berliner Philharmonie by Hans Sharon, and a classical shoebox design like the Vienna Musikverein or the Boston Symphony Hall. Lillian Disney made a gift of $50 million in 1987 to build a performance venue as a gift to the people of Los Angeles. The Frank Gehry-designed building opened on October 24,2003, the project was launched in 1987, when Lillian Disney, widow of Walt Disney, donated $50 million. Frank Gehry delivered completed designs in 1991, construction of the underground parking garage began in 1992 and was completed in 1996. The garage cost had been $110 million, and was paid for by Los Angeles County, construction of the concert hall itself stalled from 1994 to 1996 due to lack of fundraising. Additional funds were required since the construction cost of the final project far exceeded the original budget, plans were revised, and in a cost-saving move the originally designed stone exterior was replaced with a less costly stainless steel skin. The needed fundraising restarted in earnest in 1996, headed by Eli Broad, groundbreaking for the hall was held in December 1999. Delay in the project completion caused many problems for the county of LA. The County expected to repay the debts by revenue coming from the Disney Hall parking users. Upon completion in 2003, the project cost an estimated $274 million, the remainder of the total cost was paid by private donations, of which the Disney familys contribution was estimated to $84.5 million with another $25 million from The Walt Disney Company. By comparison, the three existing halls of the Music Center cost $35 million in the 1960s, performers and critics agreed that it was well worth this extra time taken by the time the hall opened to the public. During the summer rehearsals a few hundred VIPs were invited to sit in including donors, board members, … This time, the hall miraculously came to life. Earlier, the sound, wonderful as it was, had felt confined to the stage. Now a new sonic dimension had been added, and every inch of air in Disney vibrated merrily. Toyota says that he had never experienced such a difference between a first and second rehearsal in any of the halls he designed in his native Japan. Salonen could hardly believe his ears, to his amazement, he discovered that there were wrong notes in the printed parts of the Ravel that sit on the players stands. The orchestra has owned these scores for decades, but in the Chandler no conductor had ever heard the details well enough to notice the errors
Walt Disney Concert Hall
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Walt Disney Concert Hall
Walt Disney Concert Hall
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Disney Hall midway through construction, July 14, 2001.
Walt Disney Concert Hall
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Walt Disney Concert Hall Sign
Walt Disney Concert Hall
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The exterior of Founders room after panels were re-surfaced.
2.
Steel
–
Steel is an alloy of iron and other elements, primarily carbon, that is widely used in construction and other applications because of its high tensile strength and low cost. Steels base metal is iron, which is able to take on two forms, body centered cubic and face centered cubic, depending on its temperature. It is the interaction of those allotropes with the elements, primarily carbon. In the body-centred cubic arrangement, there is an atom in the centre of each cube. Carbon, other elements, and inclusions within iron act as hardening agents that prevent the movement of dislocations that otherwise occur in the lattices of iron atoms. The carbon in steel alloys may contribute up to 2. 1% of its weight. Steels strength compared to pure iron is possible at the expense of irons ductility. With the invention of the Bessemer process in the mid-19th century and this was followed by Siemens-Martin process and then Gilchrist-Thomas process that refined the quality of steel. With their introductions, mild steel replaced wrought iron, further refinements in the process, such as basic oxygen steelmaking, largely replaced earlier methods by further lowering the cost of production and increasing the quality of the product. Today, steel is one of the most common materials in the world and it is a major component in buildings, infrastructure, tools, ships, automobiles, machines, appliances, and weapons. Modern steel is generally identified by various grades defined by assorted standards organizations, the noun steel originates from the Proto-Germanic adjective stakhlijan, which is related to stakhla. The carbon content of steel is between 0. 002% and 2. 1% by weight for plain iron–carbon alloys and these values vary depending on alloying elements such as manganese, chromium, nickel, iron, tungsten, carbon and so on. Basically, steel is an alloy that does not undergo eutectic reaction. In contrast, cast iron does undergo eutectic reaction, too little carbon content leaves iron quite soft, ductile, and weak. Carbon contents higher than those of steel make an alloy, commonly called pig iron, while iron alloyed with carbon is called carbon steel, alloy steel is steel to which other alloying elements have been intentionally added to modify the characteristics of steel. Common alloying elements include, manganese, nickel, chromium, molybdenum, boron, titanium, vanadium, tungsten, cobalt, and niobium. Additional elements are important in steel, phosphorus, sulfur, silicon, and traces of oxygen, nitrogen, and copper. Alloys with a higher than 2. 1% carbon content, depending on other element content, cast iron is not malleable even when hot, but it can be formed by casting as it has a lower melting point than steel and good castability properties
Steel
–
The
steel cable of a
colliery winding tower
Steel
–
Steels and other iron–carbon alloy phases
Steel
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Iron ore pellets for the production of steel
Steel
–
A Bessemer converter in
Sheffield,
England
3.
Ferrite (iron)
–
Ferrite, is a body-centered cubic form of iron. It is this structure which gives steel and cast iron their magnetic properties. It has a strength of 280 N/mm2 and a hardness of approximately 80 Brinell, below 910 °C the body-center-cubic allotrope of pure iron is stable. Above this temperature the face-centred cubic allotrope of iron, austenite is stable, above 1,390 °C, up to the melting point at 1,539 °C, the body-centred cubic crystal structure is again the more stable form, as delta-ferrite. Ferrite above the critical temperature A2 of 771 °C, where it is rather than ferromagnetic. The term is beta ferrite or beta iron, the term beta iron is not any longer used because it is crystallographically identical to, and its phase field contiguous with, α-Iron. Only a very small amount of carbon can be dissolved in ferrite, hence the enthalpy of mixing is positive, but the contribution of entropy to the free energy of solution stabilises the structure at low carbon content. 723 °C also is the temperature at which iron-carbon austenite is stable. Mild steel consist mostly of ferrite and increasing amounts of cementite in a structure called pearlite. Since bainite and pearlite each have ferrite as a component, any iron-carbon alloy will contain some amount of ferrite if it is allowed to reach equilibrium at room temperature, the exact amount of ferrite will depend on the cooling processes the iron-carbon alloy undergoes as it cools. Because of its significance for planetary cores, the properties of iron at high pressures and temperatures have also been studied extensively. Acicular ferrite Ausferrite Martensite Zinc ferrite Magnetite Smith, William F. Hashemi, Javad, Foundations of Materials Science and Engineering, McGraw-Hill, ISBN 0-07-295358-6
Ferrite (iron)
–
Steels and other iron–carbon alloy phases
4.
Austenite
–
Austenite, also known as gamma-phase iron, is a metallic, non-magnetic allotrope of iron or a solid solution of iron, with an alloying element. In plain-carbon steel, austenite exists above the eutectoid temperature of 1000 K. The austenite allotrope exists at room temperature in stainless steel and it is named after Sir William Chandler Roberts-Austen. From 912 to 1,394 °C alpha iron undergoes a transition from body-centred cubic to the face-centred cubic configuration of gamma iron. This is similarly soft and ductile but can dissolve considerably more carbon and this gamma form of iron is exhibited by the most commonly used type of stainless steel for making hospital and food-service equipment. Austenitization means to heat the iron, iron-based metal, or steel to a temperature at which it changes crystal structure from ferrite to austenite, the more open structure of the austenite is then able to absorb carbon from the iron-carbides in carbon steel. An incomplete initial austenitization can leave undissolved carbides in the matrix, for some irons, iron-based metals, and steels, the presence of carbides may occur during the austenitization step. The term commonly used for this is two-phase austenitization, austempering is a hardening process that is used on iron-based metals to promote better mechanical properties. The metal is heated into the region of the iron-cementite phase diagram. The metal is annealed in this temperature range until the austenite turns to bainite or ausferrite, by changing the temperature for austenitization, the austempering process can yield different and desired microstructures. A higher austenitization temperature can produce a carbon content in austenite. The carbon content in austenite as a function of austempering time has been established, as austenite cools, the carbon diffuses out of the austenite and forms carbon rich iron-carbide and leaves behind carbon poor ferrite. Depending on alloy composition, a layering of ferrite and cementite, called pearlite and this is a very important case, as the carbon does not have time to diffuse due to the high cooling rate, which results in carbon being trapped and as a result forms hard martensite. Too high a rate of thick sections may cause the outer layers of the heat treated part to transform from austenite while the inner portion is still in its less dense austenite form. The difference in rates of the inner and outer portion of the part may cause cracks to develop in the outer portion. By alloying the steel with tungsten, the diffusion is slowed. Such a material is said to have its hardenability increased, tempering following quenching will transform some of the brittle martensite into tempered martensite. Heating white cast iron above 727 °C causes the formation of austenite in crystals of primary cementite and this austenisation of white iron occurs in primary cementite at the interphase boundary with ferrite
Austenite
–
Steels and other iron–carbon alloy phases
5.
Cementite
–
Cementite, also known as iron carbide, is an intermetallic compound of iron and carbon, more precisely an intermediate transition metal carbide with the formula Fe3C. By weight, it is 6. 67% carbon and 93. 3% iron and it has an orthorhombic crystal structure. It is a hard, brittle material, normally classified as a ceramic in its pure form, therefore, in carbon steels and cast irons that are slowly cooled, a portion of the carbon is in the form of cementite. Cementite forms directly from the melt in the case of white cast iron, in carbon steel, cementite precipitates from austenite as austenite transforms to ferrite on slow cooling, or from martensite during tempering. An intimate mixture with ferrite, the product of austenite. Cementite changes from ferromagnetic to paramagnetic at its Curie temperature of approximately 480 K, a natural iron carbide occurs in iron meteorites and is called cohenite after the German mineralogist Emil Cohen, who first described it. The figure shows the behaviour at room temperature. There are other forms of iron carbides that have been identified in tempered steel. These include Epsilon carbide, hexagonal close-packed Fe2-3C, precipitates in plain-carbon steels of carbon content >0. 2%, non-stoichiometric ε-carbide dissolves above ~200 °C, where Hägg carbides and cementite begin to form. Hägg carbide, monoclinic Fe5C2, precipitates in hardened tool steels tempered at 200-300 °C, characterization of different iron carbides is not at all a trivial task, and often X-ray diffraction is complemented by Mössbauer spectroscopy. Foundations of Materials Science and Engineering, microstructure of Steels and Cast Irons. Ester Esna du Plessis The Crystal Structures of Iron Carbides, Ph. D, formation of Fe7C3 and Fe5C2 type metastable carbides during the crystallization of an amorphous Fe75C25 alloy
Cementite
–
Steels and other iron–carbon alloy phases
6.
Graphite
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Graphite, archaically referred to as plumbago, is a crystalline form of carbon, a semimetal, a native element mineral, and one of the allotropes of carbon. Graphite is the most stable form of carbon under standard conditions, therefore, it is used in thermochemistry as the standard state for defining the heat of formation of carbon compounds. Highly ordered pyrolytic graphite or more correctly highly oriented pyrolytic graphite refers to graphite with a spread between the graphite sheets of less than 1°. The name graphite fiber is sometimes used to refer to carbon fibers or carbon fiber-reinforced polymer. Graphite occurs in rocks as a result of the reduction of sedimentary carbon compounds during metamorphism. It also occurs in rocks and in meteorites. Minerals associated with graphite include quartz, calcite, micas and tourmaline, in meteorites it occurs with troilite and silicate minerals. Small graphitic crystals in meteoritic iron are called cliftonite, Graphite is not mined in the United States, but U. S. production of synthetic graphite in 2010 was 134 kt valued at $1.07 billion. Graphite has a layered, planar structure, the individual layers are called graphene. In each layer, the atoms are arranged in a honeycomb lattice with separation of 0.142 nm. Atoms in the plane are bonded covalently, with three of the four potential bonding sites satisfied. The fourth electron is free to migrate in the plane, making graphite electrically conductive, however, it does not conduct in a direction at right angles to the plane. Bonding between layers is via weak van der Waals bonds, which allows layers of graphite to be easily separated, the two known forms of graphite, alpha and beta, have very similar physical properties, except for that the graphene layers stack slightly differently. The alpha graphite may be flat or buckled. The alpha form can be converted to the form through mechanical treatment. The acoustic and thermal properties of graphite are highly anisotropic, since phonons propagate quickly along the tightly-bound planes, graphites high thermal stability and electrical and thermal conductivity facilitate its widespread use as electrodes and refractories in high temperature material processing applications. However, in oxygen containing atmospheres graphite readily oxidizes to form CO2 at temperatures of 700 °C, Graphite is an electric conductor, consequently, useful in such applications as arc lamp electrodes. It can conduct electricity due to the vast electron delocalization within the carbon layers and these valence electrons are free to move, so are able to conduct electricity
Graphite
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Graphite specimen
Graphite
–
Scanning tunneling microscope image of graphite surface atoms
Graphite
–
Graphite plates and sheets, 10-15 cm high, Mineral specimen from Kimmirut,
Baffin Island.
Graphite
–
Graphite pencils
7.
Martensite
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It includes a class of hard minerals occurring as lath- or plate-shaped crystal grains. When viewed in section, the lenticular crystal grains may be incorrectly described as acicular. Austenite is γ-Fe, a solution of iron and alloying elements. As a result of the quenching, the cubic austenite transforms to a highly strained body-centered tetragonal form called martensite that is supersaturated with carbon. The shear deformations that result produce a number of dislocations. The highest hardness of a steel is 400 Brinell whereas martensite can achieve 700 Brinell. The martensitic reaction begins during cooling when the austenite reaches the start temperature. For a eutectoid steel, between 6 and 10% of austenite, called retained austenite, will remain. The percentage of retained austenite increases from insignificant for less than 0. 6% C steel, to 13% retained austenite at 0. 95% C, a very rapid quench is essential to create martensite. For steel 0-0. 6% carbon the martensite has the appearance of lath, for steel greater than 1% carbon it will form a plate like structure called plate martensite. Between those two percentages, the appearance of the grains is a mix of the two. The strength of the martensite is reduced as the amount of retained austenite grows, the process produces dislocation densities up to 1013/cm2. The great number of dislocations, combined with precipitates that originate and pin the dislocations in place, thus, martensite can be thermally induced or stress induced. One of the differences between the two phases is that martensite has a tetragonal crystal structure, whereas austenite has a face-centered cubic structure. Martensite has a lower density than austenite, so that the martensitic transformation results in a change of volume. Of considerably greater importance than the change is the shear strain which has a magnitude of about 0.26. Martensite is not shown in the phase diagram of the iron-carbon system because it is not an equilibrium phase. Equilibrium phases form by slow cooling rates that allow sufficient time for diffusion, since chemical processes accelerate at higher temperature, martensite is easily destroyed by the application of heat
Martensite
–
Steels and other iron–carbon alloy phases
Martensite
–
Martensite in AISI 4140 steel
8.
Microstructure
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Microstructure is the small scale structure of a material, defined as the structure of a prepared surface of material as revealed by a microscope above 25× magnification. The microstructure of a material can strongly influence physical properties such as strength, toughness, ductility, hardness, corrosion resistance and these properties in turn govern the application of these materials in industrial practice. Microstructure at scales smaller than can be viewed with optical microscopes is often called nanostructure, the nanostructure of biological specimens is referred to as ultrastructure. A microstructure’s influence on the mechanical and physical properties of a material is governed by the different defects present or absent of the structure. These defects can take many forms but the ones are the pores. Even if those pores play an important role in the definition of the characteristics of a material. In fact, for materials, different phases can exist at the same time. These phases have different properties and if managed correctly, can prevent the fracture of the material, the concept of microstructure is observable in macrostructural features in commonplace objects. Galvanized steel, such as the casing of a lamp post or road divider, each polygon is a single crystal of zinc adhering to the surface of the steel beneath. Zinc and lead are two metals which form large crystals visible to the naked eye. The atoms in each grain are organized one of seven 3d stacking arrangements or crystal lattices. The direction of alignment of the matrices differ between adjacent crystals, leading to variance in the reflectivity of each presented face of the grains on the galvanized surface. The average grain size can be controlled by processing conditions and composition and this is to increase the strength of the material. To quantify microstructural features, both morphological and material property must be characterized, image processing is a robust technique for determination of morphological features such as volume fraction, inclusion morphology, void and crystal orientations. To acquire micrographs, optical as well as electron microscopy are commonly used, to determine material property, Nanoindentation is a robust technique for determination of properties in micron and submicron level for which conventional testing are not feasible. Conventional mechanical testing such as tensile testing or dynamic analysis can only return macroscopic properties without any indication of microstructural properties. However, nanoindentation can be used for determination of local properties of homogeneous as well as heterogeneous materials. When a polished flat sample reveals traces of its microstructure, it is normal to capture the image using macrophotography
Microstructure
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A micrograph of bronze revealing a cast dendritic structure
Microstructure
–
Metallography allows the metallurgist to study the microstructure of metals.
Microstructure
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Aluminium copper (4 at% Cu) alloy showing copper precipitation within the aluminium matrix. The image is a projection through the metal where the dark regions are plate like copper precipitates
9.
Spheroidite
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The term carbon steel may also be used in reference to steel which is not stainless steel, in this use carbon steel may include alloy steels. As the carbon percentage content rises, steel has the ability to become harder and stronger through heat treating, however, regardless of the heat treatment, a higher carbon content reduces weldability. In carbon steels, the carbon content lowers the melting point. Mild steel, also known as steel and Low carbon steel. It is now the most common form of steel because its price is relatively low while it provides material properties that are acceptable for many applications, mild steel contains approximately 0. 05–0. 25% carbon making it malleable and ductile. Mild steel has a low tensile strength, but it is cheap and easy to form. It is often used large quantities of steel are needed. The density of steel is approximately 7.85 g/cm3. Low-carbon steels suffer from yield-point runout where the material has two yield points, the first yield point is higher than the second and the yield drops dramatically after the upper yield point. If a low-carbon steel is only stressed to some point between the upper and lower yield point then the surface develop Lüder bands, low-carbon steels contain less carbon than other steels and are easier to cold-form, making them easier to handle. Carbon steels which can successfully undergo heat-treatment have a content in the range of 0. 30–1. 70% by weight. Trace impurities of other elements can have a significant effect on the quality of the resulting steel. Trace amounts of sulfur in particular make the steel red-short, that is, brittle, low-alloy carbon steel, such as A36 grade, contains about 0. 05% sulfur and melts around 1, 426–1,538 °C. Manganese is often added to improve the hardenability of low-carbon steels and these additions turn the material into a low-alloy steel by some definitions, but AISIs definition of carbon steel allows up to 1. 65% manganese by weight. Carbon steel is broken down into four classes based on content,0.05 to 0. 25% carbon content. Balances ductility and strength and has good resistance, used for large parts, forging. Very strong, used for springs, swords, and high-strength wires, steels that can be tempered to great hardness. Used for special purposes like knives, axles or punches, most steels with more than 2. 5% carbon content are made using powder metallurgy
Spheroidite
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Steels and other iron–carbon alloy phases
10.
Pearlite
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Pearlite is a two-phased, lamellar structure composed of alternating layers of ferrite and cementite that occurs in some steels and cast irons. During slow cooling of an alloy, pearlite forms by a eutectoid reaction as austenite cools below 727 °C. Pearlite is a microstructure occurring in many grades of steels. The eutectoid composition of austenite is approximately 0, likewise steels with higher carbon content will form cementite before reaching the eutectoid point. The proportion of ferrite and cementite forming above the point can be calculated from the iron/iron—carbide equilibrium phase diagram using the lever rule. Steels with pearlitic or near-pearlitic microstructure can be drawn into thin wires, such wires, often bundled into ropes, are commercially used as piano wires, ropes for suspension bridges, and as steel cord for tire reinforcement. High degrees of wire drawing leads to pearlitic wires with yield strengths of several gigapascals and it makes pearlite one of the strongest structural bulk materials on earth. Some hypereutectoid pearlitic steel wires, when cold wire drawn to true strains above 5, although pearlite is used in many engineering applications, the origin of its extreme strength is not well understood. Bainite is a structure with lamellae much smaller than the wavelength of visible light. It is prepared by rapid cooling. Unlike pearlite, whose formation involves the diffusion of all atoms, eutectoid steel can in principle be transformed completely into pearlite, hypoeutectoid steels can also be completely pearlitic if transformed at a temperature below the normal eutectoid. Pearlite can be hard and strong but is not particularly tough and it can be wear resistant because of a strong lamellar network of ferrite and cementite. Examples of applications include cutting tools, high strength wires, knives, chisels, comprehensive information on pearlite Introduction to Physical metallurgy by Sidney H. Avner, second edition, McGraw hill publications. Steels, Processing, Structure, and Performance, Chapter 15 High-Carbon Steels, Fully Pearlitic Microstructures and Applications by George Krauss,2005 Edition, ASM International
Pearlite
–
Steels and other iron–carbon alloy phases
Pearlite
–
SEM micrograph of etched pearlite, 2000X.
11.
Bainite
–
Bainite is a plate-like microstructure that forms in steels at temperatures of 250–550 °C. First described by E. S. Davenport and Edgar Bain and this critical temperature is 1000K in plain carbon steels. Davenport and Bain originally described the microstructure as being similar in appearance to tempered martensite, a fine non-lamellar structure, bainite commonly consists of cementite and dislocation-rich ferrite. The high concentration of dislocations in the present in bainite makes this ferrite harder than it normally would be. The temperature range for transformation of austenite to bainite is between those for pearlite and martensite, when formed during continuous cooling, the cooling rate to form bainite is more rapid than that required to form pearlite, but less rapid than is required to form martensite. Most alloying elements will lower the temperature required for the rate of formation of bainite. The microstructures of martensite and bainite at first seem quite similar and this is a consequence of the two microstructures sharing many aspects of their transformation mechanisms. However, morphological differences do exist that require a TEM to see, under a light microscope, the microstructure of bainite appears darker than martensite due to its low reflectivity. Bainite is an intermediate of pearlite and martensite in terms of hardness, Bain and Davenport also noted the existence of two distinct forms, upper-range bainite which formed at higher temperatures and lower-range bainite which formed near the martensite start temperature. At 900 °C a typical low-carbon steel is composed entirely of austenite, in addition to the thermodynamic considerations indicated by the phase diagram, the phase transformations in steel are heavily influenced by the chemical kinetics. This leads to the complexity of steel microstructures which are influenced by the cooling rate. However, the transformation from austenite to pearlite is a time-dependent reconstructive reaction which requires the large movement of the iron and carbon atoms. As a consequence a rapidly cooled steel may reach a temperature where pearlite can no longer form despite the reaction being incomplete and the remaining austenite being thermodynamically unstable. This non-equilibrium phase can only form at low temperatures, where the force for the reaction is sufficient to overcome the considerable lattice strain imposed by the transformation. The transformation is essentially time-independent with the phase fraction depending only the degree of cooling below the martensite start temperature. Further, it occurs without the diffusion of either substitutional or interstitial atoms, Bainite occupies a region between these two process in a temperature range where iron self-diffusion is limited but there is insufficient driving force to form martensite. A further distinction is made between so-called lower-bainite, which forms at temperatures closer to the martensite start temperature, and upper-bainite which forms at higher temperatures. This distinction arises from the rates of carbon at the temperature at which the bainite is forming
Bainite
–
Steels and other iron–carbon alloy phases
12.
Ledeburite
–
In iron and steel metallurgy, ledeburite is a mixture of 4. 3% carbon in iron and is a eutectic mixture of austenite and cementite. It is named after the metallurgist Karl Heinrich Adolf Ledebur and he was the first professor of metallurgy at the Bergakademie Freiberg. Ledeburite arises when the content is between 2. 06% and 6. 67%. The eutectic mixture of austenite and cementite is 4. 3% carbon, Fe3C, 2Fe, ledeburite-II is composed of cementite-I with recrystallized secondary cementite and of pearlite. The pearlite results from the decay of the austenite that comes from the ledeburite-I at 723 °C. During more rapid cooling, bainite can develop instead of pearlite, and with very rapid cooling martensite can develop
Ledeburite
–
Steels and other iron–carbon alloy phases
13.
Tempering (metallurgy)
–
Tempering is a process of heat treating, which is used to increase the toughness of iron-based alloys. The exact temperature determines the amount of hardness removed, and depends on both the composition of the alloy and on the desired properties in the finished product. For instance, very hard tools are often tempered at low temperatures, tempering is a heat treatment technique applied to ferrous alloys, such as steel or cast iron, to achieve greater toughness by decreasing the hardness of the alloy. The reduction in hardness is usually accompanied by an increase in ductility, tempering is usually performed after quenching, which is rapid cooling of the metal to put it in its hardest state. Tempering is accomplished by controlled heating of the quenched work-piece to a temperature below its critical temperature. Heating above this temperature is avoided, so as not to destroy the very-hard, quenched microstructure, precise control of time and temperature during the tempering process is crucial to achieve the desired balance of physical properties. Low tempering temperatures may only relieve the stresses, decreasing brittleness while maintaining a majority of the hardness. Higher tempering temperatures tend to produce a reduction in the hardness, sacrificing some yield strength. In carbon steels, tempering alters the size and distribution of carbides in the martensite, tempering is also performed on normalized steels and cast irons, to increase ductility, machinability, and impact strength. Tempering is an ancient heat-treating technique, the oldest known example of tempered martensite is a pick axe which was found in Galilee, dating from around 1200 to 1100 BC. The process was used throughout the ancient world, from Asia to Europe, tempering was often confused with quenching and, often, the term was used to describe both techniques. I shall employ the word tempering in the sense as softening. In metallurgy, one may encounter many terms that have specific meanings within the field. Terms such as hardness, impact resistance, toughness, and strength can carry many different connotations, some of the terms encountered, and their specific definitions are, Strength, also called rigidity, this is resistance to permanent deformation and tearing. Strength, in metallurgy, is still a vague term, so is usually divided into yield strength, tensile strength, shear strength. Toughness, Resistance to fracture, as measured by the Charpy test, toughness often increases as strength decreases, because a material that bends is less likely to break. Hardness, Hardness is often used to strength or rigidity but, in metallurgy. In conventional metal alloys, there is a relation between indentation hardness and tensile strength, which eases the measurement of the latter
Tempering (metallurgy)
–
Differentially tempered steel. The various colors produced indicate the temperature to which the steel was heated. Light-straw indicates 204 °C (399 °F) and light blue indicates 337 °C (639 °F).
Tempering (metallurgy)
–
Photomicrograph of martensite, a very hard
microstructure formed when steel is quenched. Tempering reduces the hardness in the martensite by transforming it into various forms of tempered martensite.
Tempering (metallurgy)
–
Pieces of through-tempered steel flatbar. The first one, on the left, is normalized steel. The second is quenched, untempered martensite. The remaining pieces have been tempered in an oven to their corresponding temperature, for an hour each. "Tempering standards" like these are sometimes used by blacksmiths for comparison, ensuring that the work is tempered to the proper color.
Tempering (metallurgy)
–
A differentially tempered sword. The center is tempered to a springy hardness while the edges are tempered to a very high hardness.
14.
Crucible steel
–
Crucible steel is a term that applies to steel made by two different methods in the modern era, although it has been produced in varying locales throughout history. It is made by melting iron and other materials in a crucible, Crucible steel was produced in South and Central Asia during the medieval era. The homogeneous crystal structure of this cast steel improved its strength, only recently it has become apparent that places in Central Asia like Merv in Turkmenistan and Akhsiket in Uzbekistan were important centres of production of crucible steel. The Central Asian finds are all from excavations and date from the 8th to 12th centuries AD, while crucible steel is more attributed to the Middle East in early times, there have been swords discovered in Europe, particularly in Scandinavia. The swords in question have the ambiguous name inlaid into it and these swords actually date to a 200-year period from the 9th century to the early 11th century. It is speculated by many that the process of making the blades originated in the Middle East, in the first centuries of the Islamic period, there appear some scientific studies on swords and steel. The best known of these are by Jabir ibn Hayyan 8th century, al-Kindi 9th century, Al-Biruni in the early 11th century, al-Tarsusi in the late 12th century, and Fakhr-i-Mudabbir 13th century. Any of these far more information about Indian and damascene steels than appears in the entire surviving literature of classical Greece. Indian/Sri Lankan crucible steel is commonly referred to as wootz, which is agreed to be an English corruption of the word ukko or hookoo. As yet the scale of excavations and surface surveys is too limited to link the literary accounts to archaeometallurgical evidence. The known sites of crucible steel production in south India, i. e. at Konasamudram and Gatihosahalli, date from at least the medieval period. One of the earliest known sites, which shows some promising evidence that may be linked to ferrous crucible processes in Kodumanal. The site is dated between the third century BC and the third century AD, by the seventeenth century the main centre of crucible steel production seems to have been in Hyderabad. The process was quite different from that recorded elsewhere. Wootz from Hyderabad or the Decanni process for making watered blades involved a co-fusion of two different kinds of iron, one was low in carbon and the other was a steel or cast iron. Wootz steel was exported and traded throughout ancient Europe, China, the Arab world, and became particularly famous in the Middle East. Recent archaeological investigations have suggested that Sri Lanka also supported innovative technologies for iron, the Sri Lankan system of crucible steel making was partially independent of the various Indian and Middle Eastern systems. Their method was something similar to the method of carburization of wrought iron, the earliest confirmed crucible steel site is located in the knuckles range in the northern area of the Central Highlands of Sri Lanka dated to 6th −10th centuries AD
Crucible steel
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Steels and other iron–carbon alloy phases
Crucible steel
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"Kirk nardeban" pattern of a sword blade made of crucible steel, Zand period: 1750–1794,
Iran. (Moshtagh Khorasani, 2006, 506)
Crucible steel
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Crucibles next to the furnace room at
Abbeydale, Sheffield
Crucible steel
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Iron production (
Ironworks)
15.
Carbon steel
–
The term carbon steel may also be used in reference to steel which is not stainless steel, in this use carbon steel may include alloy steels. As the carbon percentage content rises, steel has the ability to become harder and stronger through heat treating, however, regardless of the heat treatment, a higher carbon content reduces weldability. In carbon steels, the carbon content lowers the melting point. Mild steel, also known as steel and Low carbon steel. It is now the most common form of steel because its price is relatively low while it provides material properties that are acceptable for many applications, mild steel contains approximately 0. 05–0. 25% carbon making it malleable and ductile. Mild steel has a low tensile strength, but it is cheap and easy to form. It is often used large quantities of steel are needed. The density of steel is approximately 7.85 g/cm3. Low-carbon steels suffer from yield-point runout where the material has two yield points, the first yield point is higher than the second and the yield drops dramatically after the upper yield point. If a low-carbon steel is only stressed to some point between the upper and lower yield point then the surface develop Lüder bands, low-carbon steels contain less carbon than other steels and are easier to cold-form, making them easier to handle. Carbon steels which can successfully undergo heat-treatment have a content in the range of 0. 30–1. 70% by weight. Trace impurities of other elements can have a significant effect on the quality of the resulting steel. Trace amounts of sulfur in particular make the steel red-short, that is, brittle, low-alloy carbon steel, such as A36 grade, contains about 0. 05% sulfur and melts around 1, 426–1,538 °C. Manganese is often added to improve the hardenability of low-carbon steels and these additions turn the material into a low-alloy steel by some definitions, but AISIs definition of carbon steel allows up to 1. 65% manganese by weight. Carbon steel is broken down into four classes based on content,0.05 to 0. 25% carbon content. Balances ductility and strength and has good resistance, used for large parts, forging. Very strong, used for springs, swords, and high-strength wires, steels that can be tempered to great hardness. Used for special purposes like knives, axles or punches, most steels with more than 2. 5% carbon content are made using powder metallurgy
Carbon steel
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Steels and other iron–carbon alloy phases
16.
Spring steel
–
Spring steel is a name given to a wide range of steels used widely in the manufacture of springs, prominently in automotive and industrial suspension applications. These steels are generally low-alloy, medium-carbon steel or high-carbon steel with a high yield strength. This allows objects made of spring steel to return to their original shape despite significant deflection or twisting, many grades of steel can be hardened and tempered to suit application as a spring, however, some steels exhibit more desirable characteristics for spring applications. Applications include piano wire such as ASTM A228, spring clamps, antennas, springs, and vehicle coil springs, leaf springs, and s-tines. Spring steel is commonly used in the manufacture of metal swords both historically and for stage combat due to its resistance to bending, snapping or shattering. Spring steel is one of the most popular used in the fabrication of lockpicks due to its pliability. Tubular spring steel is used in the gear of some small aircraft due to its ability to absorb the impact of landing. It is also used in the making of knives, especially for the Nepalese kukri. It is used in binder clips, martensite Bibliography Oberg, Erik, Franklin D. Jones, Holbrook L. Horton, Henry H. Ryffel. Christopher J. McCauley, Riccardo Heald, Muhammed Iqbal Hussain, eds
Spring steel
–
Steels and other iron–carbon alloy phases
17.
Alloy steel
–
Alloy steel is steel that is alloyed with a variety of elements in total amounts between 1. 0% and 50% by weight to improve its mechanical properties. Alloy steels are broken down into two groups, low-alloy steels and high-alloy steels, the difference between the two is somewhat arbitrary, Smith and Hashemi define the difference at 4. 0%, while Degarmo, et al. define it at 8. 0%. Most commonly, the alloy steel refers to low-alloy steels. Strictly speaking, every steel is an alloy, but not all steels are called alloy steels, the simplest steels are iron alloyed with carbon. However, the alloy steel is the standard term referring to steels with other alloying elements added deliberately in addition to the carbon. Common alloyants include manganese, nickel, chromium, molybdenum, vanadium, silicon, less common alloyants include aluminum, cobalt, copper, cerium, niobium, titanium, tungsten, tin, zinc, lead, and zirconium. The following is a range of improved properties in alloy steels, strength, hardness, toughness, wear resistance, corrosion resistance, hardenability, to achieve some of these improved properties the metal may require heat treating. Some of these uses in exotic and highly-demanding applications, such as in the turbine blades of jet engines, in spacecraft. Because of the properties of iron, some steel alloys find important applications where their responses to magnetism are very important, including in electric motors. A few common low alloy steels are, D6AC 300M 256A Alloying elements are added to certain properties in the material. Manganese, silicon, or aluminum are added during the process to remove dissolved oxygen, sulfur. Manganese, silicon, nickel, and copper are added to increase strength by forming solid solutions in ferrite, chromium, vanadium, molybdenum, and tungsten increase strength by forming second-phase carbides. Nickel and copper improve corrosion resistance in small quantities, zirconium, cerium, and calcium increase toughness by controlling the shape of inclusions. Sulfur lead, bismuth, selenium, and tellurium increase machinability, the alloying elements tend to form either solid solutions or compounds or carbides. Nickel is very soluble in ferrite, therefore, it forms compounds, aluminium dissolves in the ferrite and forms the compounds Al2O3 and AlN. Silicon is also very soluble and usually forms the compound SiO2•MxOy, manganese mostly dissolves in ferrite forming the compounds MnS, MnO•SiO2, but will also form carbides in the form of 3C. Chromium forms partitions between the ferrite and carbide phases in steel, forming C, Cr7C3, and Cr23C6, the type of carbide that chromium forms depends on the amount of carbon and other types of alloying elements present. Tungsten and molybdenum form carbides if there is enough carbon and an absence of stronger carbide forming elements, they form the carbides W2C and Mo2C, vanadium, titanium, and niobium are strong carbide forming elements, forming vanadium carbide, titanium carbide, and niobium carbide, respectively
Alloy steel
–
Steels and other iron–carbon alloy phases
18.
Maraging steel
–
Maraging steels are steels that are known for possessing superior strength and toughness without losing malleability, although they cannot hold a good cutting edge. Aging refers to the extended heat-treatment process and these steels are a special class of low-carbon ultra-high-strength steels that derive their strength not from carbon, but from precipitation of intermetallic compounds. The principal alloying element is 15 to 25 wt. % nickel, secondary alloying elements, which include cobalt, molybdenum, and titanium, are added to produce intermetallic precipitates. Original development was carried out on 20 and 25 wt. % nickel, 8–12 wt. % cobalt, 3–5 wt. % molybdenum, addition of chromium produces stainless grades resistant to corrosion. Alternative variants of Ni-reduced maraging steels are based on alloys of Fe and Mn plus minor additions of Al, Ni, the Mn has a similar effect as Ni, i. e. it stabilizes the austenite phase. Hence, depending on their Mn content, Fe-Mn maraging steels can be fully martensitic after quenching them from the high temperature austenite phase or they can contain retained austenite, the latter effect enables the design of maraging-TRIP steels where TRIP stands for Transformation-Induced-Plasticity. Due to the low carbon content maraging steels have good machinability, prior to aging, they may also be cold rolled to as much as 90% without cracking. Maraging steels offer good weldability, but must be aged afterward to restore the properties to the heat affected zone. When heat-treated the alloy has very little change, so it is often machined to its final dimensions. Due to the alloy content maraging steels have a high hardenability. Since ductile FeNi martensites are formed upon cooling, cracks are non-existent or negligible, the steels can be nitrided to increase case hardness, and polished to a fine surface finish. Non-stainless varieties of maraging steel are moderately corrosion-resistant, and resist stress corrosion, corrosion-resistance can be increased by cadmium plating or phosphating. There is also a family of cobalt-free maraging steels which are cheaper but not quite as strong, there has been Russian and Japanese research in Fe-Ni-Mn maraging alloys. The steel is first annealed at approximately 820 °C for 15–30 minutes for thin sections and for 1 hour per 25 mm thickness for heavy sections and this is followed by air cooling to room temperature to form a soft, heavily-dislocated iron-nickel lath martensite. Overaging leads to a reduction in stability of the primary, metastable, coherent precipitates, leading to their dissolution, further excessive heat-treatment brings about the decomposition of the martensite and reversion to austenite. Maraging steels strength and malleability in the stage allows it to be formed into thinner rocket and missile skins than other steels. Maraging steels have very stable properties, and, even after overaging due to excessive temperature and these alloys retain their properties at mildly elevated operating temperatures and have maximum service temperatures of over 400 °C. They are suitable for engine components, such as crankshafts and gears, and their uniform expansion and easy machinability before aging make maraging steel useful in high-wear components of assembly lines and dies
Maraging steel
–
Steels and other iron–carbon alloy phases
19.
Weathering steel
–
U. S. Steel holds the registered trademark on the name COR-TEN. Although USS sold its discrete plate business to International Steel Group in 2003, it still sells COR-TEN branded material in strip-mill plate, the original COR-TEN received the standard designation A242 from the ASTM International standards group. Newer ASTM grades are A588 and A606 for thin sheet, all alloys are in common production and use. Weathering refers to the composition of these steels, allowing them to exhibit increased resistance to atmospheric corrosion compared to other steels. This is because the forms a protective layer on its surface under the influence of the weather. The corrosion-retarding effect of the layer is produced by the particular distribution and concentration of alloying elements in it. The layer protecting the surface develops and regenerates continuously when subjected to the influence of the weather, in other words, the steel is allowed to rust in order to form the protective coating. The mechanical properties of weathering steels depend on which alloy and how thick the material is. The original A242 alloy has a strength of 50 kilopounds per square inch. It has yield strength of 46 ksi and ultimate strength of 67 ksi for medium weight rolled shapes and plates from 0. 75–1 inch thick. The thickest rolled sections and plates – from 1. 5–4 in thick have yield strength of 42 ksi, a 588 has a yield strength of at least 50 ksi, and ultimate tensile strength of 70 ksi for all rolled shapes and plate thicknesses up to 4 in thick. It is very used in marine transportation, in the construction of intermodal containers as well as visible sheet piling along recently widened sections of Londons M25 motorway. The first use of weathering steel for architectural applications was the John Deere World Headquarters in Moline, the building was designed by architect Eero Saarinen, and completed in 1964. The main buildings of Odense University, designed by Knud Holscher and Jørgen Vesterholt and built 1971–1976, are clad in weathering steel, earning them the nickname Rustenborg. In 1977, Robert Indiana created a Hebrew version of the Love sculpture made from weathering steel using the four-letter word ahava for the Israel Museum Art Garden in Jerusalem, in Denmark, all masts for supporting the catenary on electrified railways are made of weathering steel for aesthetic reasons. Weathering steel was used in 1971 for the Highliner electric cars built by the St. Louis Car Company for Illinois Central Railroad, the use of weathering steel was seen as a cost-cutting move in comparison with the contemporary railcar standard of stainless steel. A subsequent order in 1979 was built to similar specs, including weathering steel bodies, the cars were painted, a standard practice for weathering steel railcars. The durability of weathering steel did not live up to expectations and these cars have been retired by 2016
Weathering steel
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Steels and other iron–carbon alloy phases
Weathering steel
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Cor-Ten steel – Fulcrum (1987) by
Richard Serra
Weathering steel
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Broadcasting Tower,
Leeds, United Kingdom
Weathering steel
–
Abetxuko Bridge by J. Sobrino, PEDELTA,
Abetxuko,
Vitoria, Spain
20.
Tool steel
–
Tool steel refers to a variety of carbon and alloy steels that are particularly well-suited to be made into tools. Their suitability comes from their distinctive hardness, resistance to abrasion and deformation, as a result, tool steels are suited for their use in the shaping of other materials. With a carbon content between 0. 5% and 1. 5%, tool steels are manufactured under controlled conditions to produce the required quality. The presence of carbides in their plays the dominant role in the qualities of tool steel. The four major alloying elements in tool steel that form carbides are, tungsten, the rate of dissolution of the different carbides into the austenite form of the iron determines the high temperature performance of steel. Proper heat treatment of these steels is important for adequate performance, the manganese content is often kept low to minimize the possibility of cracking during water quenching. There are six groups of tool steels, water-hardening, cold-work, shock-resistant, high-speed, hot-work, the choice of group to select depends on cost, working temperature, required surface hardness, strength, shock resistance, and toughness requirements. The more severe the service condition, the higher the content and consequent amount of carbides required for the tool steel. Tool steels are used for cutting, pressing, extruding, and coining of metals, the AISI-SAE grades of tool steel is the most common scale used to identify various grades of tool steel. Individual alloys within a grade are given a number, for example, A2, O1, W-group tool steel gets its name from its defining property of having to be water quenched. W-grade steel is essentially high carbon plain-carbon steel and this group of tool steel is the most commonly used tool steel because of its low cost compared to others. They work well for parts and applications where high temperatures are not encountered. Its hardenability is low, so W-group tool steels must be subjected to a rapid quenching, requiring the use of water and these steels can attain high hardness and are rather brittle compared to other tool steels. W-steels are still sold, especially for springs, but are less widely used than they were in the 19th. This is partly because W-steels warp and crack much more during quench than oil-quenched or air hardening steels, the toughness of W-group tool steels are increased by alloying with manganese, silicon and molybdenum. Up to 0. 20% of vanadium is used to fine grain sizes during heat treating. 0. 76–0. 90% carbon, forging dies, hammers,0. 91–1. 10% carbon, general purpose tooling applications that require a good balance of wear resistance and toughness, such as rasps, drills, cutters, and shear blades. 1. 11–1. 30% carbon, files, small drills, lathe tools, razor blades, and other light-duty applications where more wear resistance is required without great toughness
Tool steel
–
Steels and other iron–carbon alloy phases
21.
Cast iron
–
Cast iron is a group of iron-carbon alloys with a carbon content greater than 2%. Its usefulness derives from its low melting temperature. Carbon ranging from 1. 8–4 wt%, and silicon 1–3 wt% are the main alloying elements of cast iron, Iron alloys with less carbon content are known as steel. While this technically makes the Fe–C–Si system ternary, the principle of cast iron solidification can be understood from the simpler binary iron–carbon phase diagram, cast iron tends to be brittle, except for malleable cast irons. It is resistant to destruction and weakening by oxidation, the earliest cast iron artefacts date to the 5th century BC, and were discovered by archaeologists in what is now Jiangsu in China. Cast iron was used in ancient China for warfare, agriculture, during the 15th century, cast iron became utilized for artillery in Burgundy, France, and in England during the Reformation. The first cast iron bridge was built during the 1770s by Abraham Darby III, cast iron is also used in the construction of buildings. Cast iron is made by re-melting pig iron, often along with quantities of iron, steel, limestone, carbon. Phosphorus and sulfur may be burnt out of the iron, but this also burns out the carbon. Depending on the application, carbon and silicon content are adjusted to the desired levels, other elements are then added to the melt before the final form is produced by casting. Cast iron is melted in a special type of blast furnace known as a cupola. After melting is complete, the molten cast iron is poured into a furnace or ladle. Cast irons properties are changed by adding various alloying elements, or alloyants, next to carbon, silicon is the most important alloyant because it forces carbon out of solution. A low percentage of silicon allows carbon to remain in solution forming iron carbide, a high percentage of silicon forces carbon out of solution forming graphite and the production of grey cast iron. Other alloying agents, manganese, chromium, molybdenum, titanium and vanadium counteracts silicon, promotes the retention of carbon, nickel and copper increase strength, and machinability, but do not change the amount of graphite formed. The carbon in the form of graphite results in an iron, reduces shrinkage, lowers strength. Sulfur, largely a contaminant when present, forms iron sulfide, the problem with sulfur is that it makes molten cast iron viscous, which causes defects. To counter the effects of sulfur, manganese is added because the two form into manganese sulfide instead of iron sulfide, the manganese sulfide is lighter than the melt so it tends to float out of the melt and into the slag
Cast iron
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A
cast iron pan.
Cast iron
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Steels and other iron–carbon alloy phases
Cast iron
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Cast iron drain, waste and vent piping
Cast iron
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Cast iron plate on grand piano
22.
White iron
–
Cast iron is a group of iron-carbon alloys with a carbon content greater than 2%. Its usefulness derives from its low melting temperature. Carbon ranging from 1. 8–4 wt%, and silicon 1–3 wt% are the main alloying elements of cast iron, Iron alloys with less carbon content are known as steel. While this technically makes the Fe–C–Si system ternary, the principle of cast iron solidification can be understood from the simpler binary iron–carbon phase diagram, cast iron tends to be brittle, except for malleable cast irons. It is resistant to destruction and weakening by oxidation, the earliest cast iron artefacts date to the 5th century BC, and were discovered by archaeologists in what is now Jiangsu in China. Cast iron was used in ancient China for warfare, agriculture, during the 15th century, cast iron became utilized for artillery in Burgundy, France, and in England during the Reformation. The first cast iron bridge was built during the 1770s by Abraham Darby III, cast iron is also used in the construction of buildings. Cast iron is made by re-melting pig iron, often along with quantities of iron, steel, limestone, carbon. Phosphorus and sulfur may be burnt out of the iron, but this also burns out the carbon. Depending on the application, carbon and silicon content are adjusted to the desired levels, other elements are then added to the melt before the final form is produced by casting. Cast iron is melted in a special type of blast furnace known as a cupola. After melting is complete, the molten cast iron is poured into a furnace or ladle. Cast irons properties are changed by adding various alloying elements, or alloyants, next to carbon, silicon is the most important alloyant because it forces carbon out of solution. A low percentage of silicon allows carbon to remain in solution forming iron carbide, a high percentage of silicon forces carbon out of solution forming graphite and the production of grey cast iron. Other alloying agents, manganese, chromium, molybdenum, titanium and vanadium counteracts silicon, promotes the retention of carbon, nickel and copper increase strength, and machinability, but do not change the amount of graphite formed. The carbon in the form of graphite results in an iron, reduces shrinkage, lowers strength. Sulfur, largely a contaminant when present, forms iron sulfide, the problem with sulfur is that it makes molten cast iron viscous, which causes defects. To counter the effects of sulfur, manganese is added because the two form into manganese sulfide instead of iron sulfide, the manganese sulfide is lighter than the melt so it tends to float out of the melt and into the slag
White iron
–
A
cast iron pan.
White iron
–
Steels and other iron–carbon alloy phases
White iron
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Cast iron drain, waste and vent piping
White iron
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Cast iron plate on grand piano
23.
Ductile iron
–
While most varieties of cast iron are brittle, ductile iron has much more impact and fatigue resistance, due to its nodular graphite inclusions. On October 25,1949, Keith Dwight Millis, Albert Paul Gagnebin, Ductile iron is not a single material but part of a group of materials which can be produced with a wide range of properties through control of their microstructure. The common defining characteristic of this group of materials is the shape of the graphite, in ductile irons, graphite is in the form of nodules rather than flakes as in grey iron. Nodule formation is achieved by adding nodulizing elements, most commonly magnesium and, less often now, yttrium, often a component of mischmetal, has also been studied as a possible nodulizer. Austempered Ductile Iron was discovered in the 1950s but was commercialized and achieved only some years later. In ADI, the structure is manipulated through a sophisticated heat treating process. The aus portion of the name refers to austenite, improved corrosion resistance can be achieved by replacing 15% to 30% of the iron in the alloy with varying amounts of nickel, copper, or chromium. Much of the production of ductile iron is in the form of ductile iron pipe. Ductile iron is specifically useful in automotive components, where strength needs surpass that of aluminum. Other major industrial applications include off-highway diesel trucks, Class 8 trucks, agricultural tractors, in wind power industry nodular cast iron is used for hubs and structural parts like machine frames. Nodular cast iron is suitable for large and complex shapes and high loads, SG iron is used in many grand piano harps. Malleable iron Smith, William F. Hashemi, Javad, Foundations of Materials Science and Engineering, McGraw-Hill, media related to Ductile iron at Wikimedia Commons Ductile Iron Society Ductile Iron Pipe Research Association
Ductile iron
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Steels and other iron–carbon alloy phases
24.
Malleable iron
–
Malleable iron is cast as white iron, the structure being a metastable carbide in a pearlitic matrix. Through an annealing heat treatment, the structure as first cast is transformed into the malleable form. Carbon agglomerates into small roughly spherical aggregates of graphite leaving a matrix of ferrite or pearlite according to the heat treatment used. Three basic types of iron are recognized within the casting industry, blackheart malleable iron, whiteheart malleable iron. Malleable iron was used as early as the 4th century BCE, by the Tang Dynasty, the use of malleable iron in China waned, although there are malleable iron artifacts dating to the 9th century. Malleable iron is mentioned in England in a patent dating to the 1670s, réaumur conducted extensive research on malleable iron in 1720. He discovered that iron castings which were too hard to be worked could be softened by packing them into iron ore or hammer slag, creating malleable iron began in the United States in 1826 when Seth Boyden started a foundry for the production of harness hardware and other small castings. Like similar irons with the carbon formed into spherical or nodular shapes, incorrectly considered by some to be an old or dead material, malleable iron still has a legitimate place in the design engineers toolbox. Malleable iron is a choice for small castings or castings with thin cross sections. Other nodular irons produced with graphite in the shape can be difficult to produce in these applications. Malleable iron also exhibits better fracture toughness properties in low temperature environments than other nodular irons, the ductile to brittle behavior transformation temperature is lower than many other ductile iron alloys. Thicker sections of a casting will cool slowly, allowing some primary graphite to form and this graphite forms random flake-like structures and will not transform to carbide during heat treatment. When stress is applied to such a casting in application, the strength will be lower than expected for white iron. Such iron is said to have a mottled appearance, some countermeasures can be applied to enhance the formation of the all white structure, but malleable iron foundries often avoid producing heavy sections. After the casting and heat treatment processes, malleable iron can be shaped through cold working and this is possible due to malleable irons desirable property of being less strain rate sensitive than other materials. It is often used for small castings requiring good tensile strength, uses include electrical fittings, hand tools, pipe fittings, washers, brackets, fence fittings, power line hardware, farm equipment, mining hardware, and machine parts
Malleable iron
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Polycrystalline structure of malleable iron at 100x magnification
25.
Wrought iron
–
Wrought iron is an iron alloy with a very low carbon content in contrast to cast iron. It is a mass of iron with fibrous slag inclusions which gives it a grain resembling wood. Wrought iron is tough, malleable, ductile, corrosion-resistant and easily welded, before the development of effective methods of steelmaking and the availability of large quantities of steel, wrought iron was the most common form of malleable iron. A wrought product is one that has been worked by forging, extruding, rolling, hammering, etcetera, to change its form. Wrought iron is a worked iron product that is seldom produced today as other cheaper. Historically, a modest amount of iron was refined into steel. The demand for wrought iron reached its peak in the 1860s with the adaptation of ironclad warships, however, as properties such as brittleness of mild steel improved, it became less costly and more widely available than wrought iron, whose usage then declined. Wrought iron is no longer produced on a commercial scale, many products described as wrought iron, such as guard rails, garden furniture and gates, are actually made of mild steel. They retain that description because they are made to resemble objects which in the past were wrought by hand by a blacksmith, the word wrought is an archaic past participle of the verb to work, and so wrought iron literally means worked iron. Wrought iron is a term for the commodity, but is also used more specifically for finished iron goods. It was used in that sense in British Customs records. Cast iron, unlike wrought iron, is brittle and cannot be worked either hot or cold, Cast iron can break if struck with a hammer. In the 17th, 18th, and 19th centuries, wrought iron went by a variety of terms according to its form, origin. While the bloomery process produced wrought iron directly from ore, cast iron or pig iron were the materials used in the finery forge. Pig iron and cast iron have higher content than wrought iron. Cast and especially pig iron have excess slag which must be at least partially removed to produce quality wrought iron, at foundries it was common to blend scrap wrought iron with cast iron to improve the physical properties of castings. Fusion eventually became accepted as relatively more important than composition below a given low carbon concentration. Another difference is that steel can be hardened by heat treating, historically, wrought iron was known as commercially pure iron, however, it no longer qualifies because current standards for commercially pure iron require a carbon content of less than 0.008 wt%
Wrought iron
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The
Eiffel tower is constructed from
puddled iron, a form of wrought iron
Wrought iron
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Steels and other iron–carbon alloy phases
Wrought iron
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Iron pillar at Delhi, India, containing 98% wrought iron
Wrought iron
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Schematic drawing of a puddling furnace
26.
Metallurgy
–
The production of metals involves the processing of ores to extract the metal they contain, and the mixture of metals, sometimes with other elements, to produce alloys. Metallurgy is distinguished from the craft of metalworking, although metalworking relies on metallurgy, as medicine relies on medical science, Metallurgy is subdivided into ferrous metallurgy and non-ferrous metallurgy or colored metallurgy. Ferrous metallurgy involves processes and alloys based on iron while non-ferrous metallurgy involves processes, the production of ferrous metals accounts for 95 percent of world metal production. The roots of metallurgy derive from Ancient Greek, μεταλλουργός, metallourgós, worker in metal, from μέταλλον, métallon, metal + ἔργον, érgon, in the late 19th century it was extended to the more general scientific study of metals, alloys, and related processes. In English, the pronunciation is the more common one in the UK. The /ˈmetələrdʒi/ pronunciation is the common one in the USA. The earliest recorded metal employed by humans appears to be gold, small amounts of natural gold have been found in Spanish caves used during the late Paleolithic period, c.40,000 BC. Silver, copper, tin and meteoric iron can also be found in native form, egyptian weapons made from meteoric iron in about 3000 BC were highly prized as daggers from heaven. Certain metals, notably tin, lead and copper, can be recovered from their ores by simply heating the rocks in a fire or blast furnace, a process known as smelting. The first evidence of this extractive metallurgy dates from the 5th and 6th millennia BC and was found in the sites of Majdanpek, Yarmovac and Plocnik. To date, the earliest evidence of copper smelting is found at the Belovode site, other signs of early metals are found from the third millennium BC in places like Palmela, Los Millares, and Stonehenge. However, the ultimate beginnings cannot be ascertained and new discoveries are both continuous and ongoing. These first metals were single ones or as found, about 3500 BC, it was discovered that by combining copper and tin, a superior metal could be made, an alloy called bronze, representing a major technological shift known as the Bronze Age. The extraction of iron from its ore into a metal is much more difficult than for copper or tin. The process appears to have been invented by the Hittites in about 1200 BC, the secret of extracting and working iron was a key factor in the success of the Philistines. Historical developments in ferrous metallurgy can be found in a variety of past cultures. A 16th century book by Georg Agricola called De re metallica describes the highly developed and complex processes of mining metal ores, metal extraction, Agricola has been described as the father of metallurgy. Extractive metallurgy is the practice of removing valuable metals from an ore, in order to convert a metal oxide or sulphide to a purer metal, the ore must be reduced physically, chemically, or electrolytically
Metallurgy
–
Georgius Agricola, author of De re metallica, an important early work on metal extraction
Metallurgy
–
Gold headband from Thebes 750–700 BC
Metallurgy
–
Aluminium plant in
Žiar nad Hronom (Central
Slovakia)
Metallurgy
–
Casting bronze
27.
Alloy
–
An alloy is a mixture of metals or a mixture of a metal and another element. Alloys are defined by a metallic bonding character, an alloy may be a solid solution of metal elements or a mixture of metallic phases. Intermetallic compounds are alloys with a stoichiometry and crystal structure. Zintl phases are sometimes considered alloys depending on bond types. Alloys are used in a variety of applications. In some cases, a combination of metals may reduce the overall cost of the material while preserving important properties, in other cases, the combination of metals imparts synergistic properties to the constituent metal elements such as corrosion resistance or mechanical strength. Examples of alloys are steel, solder, brass, pewter, duralumin, bronze, the alloy constituents are usually measured by mass. Alloys are usually classified as substitutional or interstitial alloys, depending on the arrangement that forms the alloy. They can be classified as homogeneous, or heterogeneous or intermetallic. An alloy is a mixture of elements, which forms an impure substance that retains the characteristics of a metal. Alloys are made by mixing two or more elements, at least one of which is a metal and this is usually called the primary metal or the base metal, and the name of this metal may also be the name of the alloy. The other constituents may or may not be metals but, when mixed with the base, they will be soluble. The mechanical properties of alloys will often be different from those of its individual constituents. A metal that is very soft, such as aluminium, can be altered by alloying it with another soft metal. Although both metals are soft and ductile, the resulting aluminium alloy will have much greater strength. Adding a small amount of carbon to iron trades its great ductility for the greater strength of an alloy called steel. Due to its strength, but still substantial toughness, and its ability to be greatly altered by heat treatment, steel is one of the most useful. By adding chromium to steel, its resistance to corrosion can be enhanced, creating stainless steel, while adding silicon will alter its electrical characteristics, producing silicon steel
Alloy
–
Liquid
bronze, being poured into molds during casting.
Alloy
–
Wire rope made from
steel, which is a metal alloy whose major component is
iron, with
carbon content between 0.02% and 2.14% by mass.
Alloy
–
A
brass lamp.
Alloy
–
A gate valve, made from
Inconel.
28.
Chromium
–
Chromium is a chemical element with symbol Cr and atomic number 24. It is the first element in Group 6 and it is a steely-grey, lustrous, hard and brittle metal which takes a high polish, resists tarnishing, and has a high melting point. The name of the element is derived from the Greek word χρῶμα, chrōma, meaning color, Chromium metal is of high value for its high corrosion resistance and hardness. A major development was the discovery that steel could be highly resistant to corrosion and discoloration by adding metallic chromium to form stainless steel. Stainless steel and chrome plating together comprise 85% of the commercial use, trivalent chromium ion is an essential nutrient in trace amounts in humans for insulin, sugar and lipid metabolism, although the issue is debated. While chromium metal and Cr ions are not considered toxic, hexavalent chromium is toxic and carcinogenic, abandoned chromium production sites often require environmental cleanup. Chromium is remarkable for its properties, it is the only elemental solid which shows antiferromagnetic ordering at room temperature. Above 38 °C, it changes to paramagnetic, Chromium metal left standing in air is passivated by oxidation, forming a thin, protective, surface layer. This layer is a structure only a few molecules thick. It is very dense, and prevents the diffusion of oxygen into the underlying metal and this is different from the oxide that forms on iron and carbon steel, through which elemental oxygen continues to migrate, reaching the underlying material to cause incessant rusting. Passivation can be enhanced by short contact with oxidizing acids like nitric acid, passivated chromium is stable against acids. Passivation can be removed with a reducing agent that destroys the protective oxide layer on the metal. Chromium metal treated in this way readily dissolves in weak acids, Chromium, unlike such metals as iron and nickel, does not suffer from hydrogen embrittlement. However, it suffer from nitrogen embrittlement, reacting with nitrogen from air. Chromium is the 22nd most abundant element in Earths crust with a concentration of 100 ppm. Chromium compounds are found in the environment from the erosion of chromium-containing rocks, Chromium is mined as chromite ore. About two-fifths of the ores and concentrates in the world are produced in South Africa, while Kazakhstan, India, Russia. Untapped chromite deposits are plentiful, but geographically concentrated in Kazakhstan, although rare, deposits of native chromium exist
Chromium
–
chromium crystals
Chromium
–
Crocoite (PbCrO 4)
Chromium
–
Chromite ore
Chromium
–
Chromium(III) chloride hexahydrate ([CrCl 2 (H 2 O) 4]Cl·2H 2 O)
29.
Nutcracker
–
A nutcracker is a tool designed to open nuts by cracking their shells. There are many designs, including levers, screws, and ratchets, a well-known type portrays a person whose mouth forms the jaws of the nutcracker, though many of these are meant for decorative use. Nuts were historically opened using a hammer and anvil, often made of stone, some nuts such as walnuts can also be opened by hand, by holding the nut in the palm of the hand and applying pressure with the other palm or thumb, or using another nut. Manufacturers produce modern functional nutcrackers usually somewhat resembling pliers, but with the point at the end beyond the nut. These are also used for cracking the shells of crab and lobster to make the meat available for eating. Hinged lever nutcrackers, often called a pair of nutcrackers, may date back to Ancient Greece, by the 14th century in Europe, nutcrackers were documented in England, including in the Canterbury Tales, and in France. The lever design may derive from blacksmiths pincers, materials included metals such as silver, cast-iron and bronze, and wood including boxwood, especially those from France and Italy. Many of the wooden carved nutcrackers were in the form of people, during the Victorian era, fruit and nuts were presented at dinner and ornate and often silver-plated nutcrackers were produced to accompany them on the dinner table. Nuts have long been a choice for desserts, particularly throughout Europe. The nutcrackers were placed on dining tables to serve as a fun, at one time, nutcrackers were actually made of metals such as brass, and it was not until the 1800s in Germany that the popularity of wooden ones began to spread. After the 1960s, the availability of pre-shelled nuts led to a decline in ownership of nutcrackers, in the 17th century, screw nutcrackers were introduced that applied more gradual pressure to the shell, some like a vise. The spring-jointed nutcracker was patented by Henry Quackenbush in 1913, unshelled nuts are still popular in China, where a key device is inserted into the crack in walnuts, pecans, and macadamias and twisted to open the shell. Nutcrackers in the form of carvings of a soldier, knight, king. Figurative nutcrackers are a good luck symbol in Germany, and a tale recounts that a puppet-maker won a nutcracking challenge by creating a doll with a mouth for a lever to crack the nuts. These nutcrackers portray a person with a mouth which the operator opens by lifting a lever in the back of the figurine. Originally one could insert a nut in the mouth, press down. Modern nutcrackers in this style serve mostly for decoration, mainly at Christmas time, the ballet The Nutcracker derives its name from this festive holiday decoration. The carving of nutcrackers—as well as of religious figures and of cribs—developed as an industry in forested rural areas of Germany
Nutcracker
–
A collection of fairy tale nutcrackers
Nutcracker
–
A variety of figure nutcrackers
Nutcracker
–
Decorative brass
populuxe nutcracker by the industrial designer
Maurice Ascalon
30.
Corrosion
–
Corrosion is a natural process, which converts a refined metal to a more chemically-stable form, such as its oxide, hydroxide, or sulfide. It is the destruction of materials by chemical and/or electrochemical reaction with their environment. Corrosion engineering is the dedicated to controlling and stopping corrosion. In the most common use of the word, this means electrochemical oxidation of metal in reaction with an oxidant such as oxygen or sulfur, rusting, the formation of iron oxides, is a well-known example of electrochemical corrosion. This type of damage typically produces oxide or salt of the original metal, corrosion can also occur in materials other than metals, such as ceramics or polymers, although in this context, the term degradation is more common. Corrosion degrades the useful properties of materials and structures including strength, appearance and permeability to liquids, many structural alloys corrode merely from exposure to moisture in air, but the process can be strongly affected by exposure to certain substances. Corrosion can be concentrated locally to form a pit or crack, because corrosion is a diffusion-controlled process, it occurs on exposed surfaces. As a result, methods to reduce the activity of the surface, such as passivation and chromate conversion. However, some corrosion mechanisms are less visible and less predictable, in a galvanic couple, the more active metal corrodes at an accelerated rate and the more noble metal corrodes at a slower rate. When immersed separately, each metal corrodes at its own rate, what type of metal to use is readily determined by following the galvanic series. For example, zinc is used as a sacrificial anode for steel structures. Galvanic corrosion is of major interest to the industry and also anywhere water contacts pipes or metal structures. Factors such as size of anode, types of metal. The surface area ratio of the anode and cathode directly affects the corrosion rates of the materials, galvanic corrosion is often prevented by the use of sacrificial anodes. In any given environment, one metal will be more noble or more active than others. Two metals in electrical contact share the same electrons, so that the tug-of-war at each surface is analogous to competition for free electrons between the two materials. Using the electrolyte as a host for the flow of ions in the same direction, the resulting mass flow or electric current can be measured to establish a hierarchy of materials in the medium of interest. This hierarchy is called a series and is useful in predicting and understanding corrosion
Corrosion
–
Rust, the most familiar example of corrosion.
Corrosion
–
Volcanic gases have accelerated the corrosion of this abandoned mining machinery.
Corrosion
–
Corrosion on exposed metal.
Corrosion
–
Galvanic corrosion of aluminium. A 5-mm-thick aluminium alloy plate is physically (and hence, electrically) connected to a 10-mm-thick mild steel structural support. Galvanic corrosion occurred on the aluminium plate along the joint with the steel. Perforation of aluminium plate occurred within 2 years.
31.
Rust
–
Rust is an iron oxide, usually red oxide formed by the redox reaction of iron and oxygen in the presence of water or air moisture. Several forms of rust are distinguishable both visually and by spectroscopy, and form under different circumstances, Rust consists of hydrated iron oxides Fe2O3·nH2O and iron oxide-hydroxide. Given sufficient time, oxygen, and water, any iron mass will eventually convert entirely to rust, surface rust is flaky and friable, and it provides no protection to the underlying iron, unlike the formation of patina on copper surfaces. Rusting is the term for corrosion of iron and its alloys. Many other metals undergo similar corrosion, but the resulting oxides are not commonly called rust, other forms of rust exist, like the result of reactions between iron and chloride in an environment deprived of oxygen. Rebar used in concrete pillars, which generates green rust, is an example. Rust is another name for iron oxide, which occurs when iron or an alloy that contains iron, like steel, is exposed to oxygen and moisture for a long period of time. Over time, the oxygen combines with the metal at a level, forming a new compound called an oxide. Although some people refer to rust generally as oxidation, that term is more general, although rust forms when iron undergoes oxidation. Only iron or alloys that contain iron can rust, but other metals can corrode in similar ways, the main catalyst for the rusting process is water. Iron or steel structures might appear to be solid, but water molecules can penetrate the microscopic pits, the hydrogen atoms present in water molecules can combine with other elements to form acids, which will eventually cause more metal to be exposed. If chloride ions are present, as is the case with saltwater, meanwhile, the oxygen atoms combine with metallic atoms to form the destructive oxide compound. As the atoms combine, they weaken the metal, making the structure brittle, when impure iron is in contact with water, oxygen, other strong oxidants, or acids, it rusts. If salt is present, for example in seawater or salt spray, iron metal is relatively unaffected by pure water or by dry oxygen. As with other metals, like aluminium, a tightly adhering oxide coating, the conversion of the passivating ferrous oxide layer to rust results from the combined action of two agents, usually oxygen and water. Other degrading solutions are sulfur dioxide in water and carbon dioxide in water, under these corrosive conditions, iron hydroxide species are formed. Unlike ferrous oxides, the hydroxides do not adhere to the bulk metal, when iron rusts, the oxides take up more volume than the original metal, this expansion can generate enormous forces, damaging structures made with iron. See Economic effect for more details, the rusting of iron is an electrochemical process that begins with the transfer of electrons from iron to oxygen
Rust
–
Colors and porous surface texture of rust
Rust
–
Steels and other iron–carbon alloy phases
Rust
–
Heavy rust on the links of a chain near the
Golden Gate Bridge in
San Francisco; it was continuously exposed to moisture and
salt spray, causing surface breakdown, cracking, and flaking of the metal.
Rust
–
Outdoors Rust Wedge display at the
Exploratorium shows the enormous expansive force of rusting iron
32.
Salinity
–
Salinity is the saltiness or amount of salt dissolved in a body of water. This is usually measured in g salt k g sea water, a contour line of constant salinity is called an isohaline – or sometimes isohale. Salinity in rivers, lakes, and the ocean is conceptually simple, conceptually the salinity is the quantity of dissolved salt content of the water. Salts are compounds like sodium chloride, magnesium sulfate, potassium nitrate, the concentration of dissolved chloride ions is sometimes referred to as chlorinity. Operationally, dissolved matter is defined as that which can pass through a fine filter. Salinity can be expressed in the form of a mass fraction, Seawater typically has a mass salinity of around 35 g/kg, although lower values are typical near coasts where rivers enter the ocean. Rivers and lakes can have a range of salinities, from less than 0.01 g/kg to a few g/kg. The Dead Sea has a salinity of more than 200 g/kg, whatever pore size is used in the definition, the resulting salinity value of a given sample of natural water will not vary by more than a few percent. A bottled seawater product known as IAPSO Standard Seawater is used by oceanographers to standardize their measurements with enough precision to meet this requirement, measurement and definition difficulties arise because natural waters contain a complex mixture of many different elements from different sources in different molecular forms. The chemical properties of some of these depend on temperature and pressure. Many of these forms are difficult to measure with high accuracy, different practical definitions of salinity result from different attempts to account for these problems, to different levels of precision, while still remaining reasonably easy to use. For many purposes this sum can be limited to a set of eight major ions in natural waters, the major ions dominate the inorganic composition of most natural waters. Exceptions include some pit lakes and waters from some hydrothermal springs, the concentrations of dissolved gases like oxygen and nitrogen are not usually included in descriptions of salinity. However, carbon dioxide gas, which when dissolved is partially converted into carbonates and bicarbonates, is often included. Silicon in the form of acid, which usually appears as a neutral molecule in the pH range of most natural waters. The term salinity is, for oceanographers, usually associated with one of a set of measurement techniques. As the dominant techniques evolve, so do different descriptions of salinity, the distinctions between these different descriptions are important to physical oceanographers but are obscure and confusing to nonspecialists. Salinities were largely measured using titration-based techniques before the 1980s, titration with silver nitrate could be used to determine the concentration of halide ions to give a chlorinity
Salinity
–
Global map of average sea surface salinity (SSS)
Salinity
–
Annual mean sea surface salinity for the
World Ocean. Data from the
World Ocean Atlas 2009.
Salinity
–
International Association for the Physical Sciences of the Oceans (IAPSO) standard seawater.
Salinity
–
Global map of average sea surface density
33.
Corrosion resistance
–
Corrosion is a natural process, which converts a refined metal to a more chemically-stable form, such as its oxide, hydroxide, or sulfide. It is the destruction of materials by chemical and/or electrochemical reaction with their environment. Corrosion engineering is the dedicated to controlling and stopping corrosion. In the most common use of the word, this means electrochemical oxidation of metal in reaction with an oxidant such as oxygen or sulfur, rusting, the formation of iron oxides, is a well-known example of electrochemical corrosion. This type of damage typically produces oxide or salt of the original metal, corrosion can also occur in materials other than metals, such as ceramics or polymers, although in this context, the term degradation is more common. Corrosion degrades the useful properties of materials and structures including strength, appearance and permeability to liquids, many structural alloys corrode merely from exposure to moisture in air, but the process can be strongly affected by exposure to certain substances. Corrosion can be concentrated locally to form a pit or crack, because corrosion is a diffusion-controlled process, it occurs on exposed surfaces. As a result, methods to reduce the activity of the surface, such as passivation and chromate conversion. However, some corrosion mechanisms are less visible and less predictable, in a galvanic couple, the more active metal corrodes at an accelerated rate and the more noble metal corrodes at a slower rate. When immersed separately, each metal corrodes at its own rate, what type of metal to use is readily determined by following the galvanic series. For example, zinc is used as a sacrificial anode for steel structures. Galvanic corrosion is of major interest to the industry and also anywhere water contacts pipes or metal structures. Factors such as size of anode, types of metal. The surface area ratio of the anode and cathode directly affects the corrosion rates of the materials, galvanic corrosion is often prevented by the use of sacrificial anodes. In any given environment, one metal will be more noble or more active than others. Two metals in electrical contact share the same electrons, so that the tug-of-war at each surface is analogous to competition for free electrons between the two materials. Using the electrolyte as a host for the flow of ions in the same direction, the resulting mass flow or electric current can be measured to establish a hierarchy of materials in the medium of interest. This hierarchy is called a series and is useful in predicting and understanding corrosion
Corrosion resistance
–
Rust, the most familiar example of corrosion.
Corrosion resistance
–
Volcanic gases have accelerated the corrosion of this abandoned mining machinery.
Corrosion resistance
–
Corrosion on exposed metal.
Corrosion resistance
–
Galvanic corrosion of aluminium. A 5-mm-thick aluminium alloy plate is physically (and hence, electrically) connected to a 10-mm-thick mild steel structural support. Galvanic corrosion occurred on the aluminium plate along the joint with the steel. Perforation of aluminium plate occurred within 2 years.
34.
Iron oxide
–
Iron oxides are chemical compounds composed of iron and oxygen. All together, there are sixteen known iron oxides and oxyhydroxides, common rust is a form of iron oxide. Iron oxides are used as inexpensive, durable pigments in paints, coatings. Colors commonly available are in the end of the yellow/orange/red/brown/black range. When used as a coloring, it has E number E172. Limonite Iron oxide nanoparticles List of inorganic pigments Information from Nano-Oxides, http, //chemed. chem. purdue. edu/demos/demosheets/12.3. html http, //minerals. usgs. gov/minerals/pubs/commodity/iron_oxide/ CDC - NIOSH Pocket Guide to Chemical Hazards de
Iron oxide
–
Iron oxide pigment
35.
Passivation (chemistry)
–
Passivation, in physical chemistry and engineering, refers to a material becoming passive, that is, less affected or corroded by the environment of future use. As a technique, passivation is the use of a coat of a protective material, such as metal oxide. Passivation can occur only in conditions, and is used in microelectronics to enhance silicon. The technique of passivation strengthens and preserves the appearance of metallics, other proprietary systems to avoid electrode passivation, several discussed below, are the subject of ongoing research and development. When exposed to air, many metals naturally form a hard, relatively inert surface, in the case of other metals, such as iron, a somewhat rough porous coating is formed from loosely adherent corrosion products. In this case, an amount of metal is removed. There has been much interest in determining the mechanisms that govern the increase of thickness of the oxide layer over time, boundaries between micro grains, if the oxide layer is crystalline, form an important pathway for oxygen to reach the unoxidized metal below. For this reason, vitreous oxide coatings – which lack grain boundaries – can retard oxidation, the conditions necessary for passivation are recorded in Pourbaix diagrams. Some corrosion inhibitors help the formation of a layer on the surface of the metals to which they are applied. Some compounds, dissolving in solutions form non-reactive and low solubility films on metal surfaces, schönbein named the first state the active condition and the second the passive condition. If passive iron is touched by active iron, it becomes active again, in 1920, Ralph S. Lillie measured the effect of an active piece of iron touching a passive iron wire and found that a wave of activation sweeps rapidly over its whole length. In the area of microelectronics, the formation of a strongly adhering passivating oxide is important to the performance of silicon. In the area of photovoltaics, a surface layer such as silicon nitride. Aluminium alloys, however, offer protection against corrosion. There are three ways to passivate these alloys, alclading, chromate conversion coating and anodizing. Alclading is the process of bonding a thin layer of pure aluminium to the aluminium alloy. Chromate conversion coating is a way of passivating not only aluminum, but also zinc, cadmium, copper, silver, magnesium. Anodizing forms an oxide coating
Passivation (chemistry)
–
Pourbaix diagram of iron.
36.
Chromium(III) oxide
–
Chromium oxide is the inorganic compound of the formula Cr 2O3. It is one of the oxides of chromium and is used as a pigment. In nature, it occurs as the rare mineral eskolaite, Cr 2O3 adopts the corundum structure, consisting of a hexagonal close packed array of oxide anions with ⅔ of the octahedral holes occupied by chromium. Similar to corundum, Cr 2O3 is a hard, brittle material and it is antiferromagnetic up to 307 K, the Néel temperature. It is not readily attacked by acids or bases, although molten alkali gives chromate salts with the CrO−4 anion and it turns brown when heated, but reverts to its dark green color when cooled. Cr 2O3 occurs naturally in mineral eskolaite, which is found in chromium-rich tremolite skarns, metaquartzites, eskolaite is also a rare component of chondrite meteorites. The mineral is named after Finnish geologist Pentti Eskola, the Parisians Pannetier and Binet first prepared the transparent hydrated form of Cr 2O3 in 1838 via a secret process, sold as a pigment. It is derived from the mineral chromite, Cr 2O4, 2Cr 2O7 → Cr 2O3 + N2 +4 H 2O The reaction has a low ignition temperature of less than 200 °C and is frequently used in “volcano” demonstrations. Because of its stability, chromia is a commonly used pigment and was originally called viridian. It is used in paints, inks, and glasses and it is the colourant in chrome green and institutional green. On a piece of leather, balsa, cloth or other material, in this context it is alternatively known as green compound. Although insoluble in water, it dissolves in acid to produce hydrated chromium ions and it dissolves in concentrated alkali to yield chromite ions. When heated with finely divided carbon it can be reduced to metal with release of carbon dioxide. Because of the high melting point of chromium, chromium thermite casting is impractical
Chromium(III) oxide
–
Chromium(III) oxide
Chromium(III) oxide
–
Eskolaite mineral
37.
Lustre (mineralogy)
–
Lustre or luster is the way light interacts with the surface of a crystal, rock, or mineral. The word traces its origins back to the latin lux, meaning light, a range of terms are used to describe lustre, such as earthy, metallic, greasy, and silky. Similarly, the term refers to a glassy lustre. A list of terms is given below. Lustre varies over a continuum, and so there are no rigid boundaries between the different types of lustre. The terms are frequently combined to describe types of lustre. Some minerals exhibit unusual optical phenomena, such as asterism or chatoyancy, a list of such phenomena is given below. Adamantine minerals possess a superlative lustre, which is most notably seen in diamond, such minerals are transparent or translucent, and have a high refractive index. Minerals with an adamantine lustre are uncommon, with examples being cerussite. Minerals with a degree of lustre are referred to as subadamantine, with some examples being garnet. Dull minerals exhibit little to no lustre, due to coarse granulations which scatter light in all directions, a distinction is sometimes drawn between dull minerals and earthy minerals, with the latter being coarser, and having even less lustre. Greasy minerals resemble fat or grease, a greasy lustre often occurs in minerals containing a great abundance of microscopic inclusions, with examples including opal and cordierite. Many minerals with a greasy lustre also feel greasy to the touch, metallic minerals have the lustre of polished metal, and with ideal surfaces will work as a reflective surface. Examples include galena, pyrite and magnetite, pearly minerals consist of thin transparent co-planar sheets. Light reflecting from these layers give them a lustre reminiscent of pearls, such minerals possess perfect cleavage, with examples including muscovite and stilbite. Resinous minerals have the appearance of resin, chewing gum or plastic, a principal example is amber, which is a form of fossilized resin. Silky minerals have an arrangement of extremely fine fibres, giving them a lustre reminiscent of silk. Examples include asbestos, ulexite and the satin spar variety of gypsum, a fibrous lustre is similar, but has a coarser texture
Lustre (mineralogy)
–
Cut diamonds.
Lustre (mineralogy)
–
Kaolinite
Lustre (mineralogy)
–
Moss
opal
Lustre (mineralogy)
–
Pyrite
38.
Steel mill
–
Steel Mill was an early Bruce Springsteen band. Other members of the band included three members of the E Street Band - Vini Lopez, Danny Federici and Steve Van Zandt. As well as playing on the Jersey Shore, Steel Mill also played regularly in Richmond, Virginia and played gigs in California and they opened for acts such as Chicago, Boz Scaggs, Grand Funk Railroad, Roy Orbison, Ike & Tina Turner and Black Sabbath. Since 2004 Vini Lopez has led Steel Mill Retro which has performed and recorded original Springsteen songs from the Steel Mill era, Roslin was one of the judges while Springsteen and Lopez competed in the competition with their respective bands, The Castiles and Sonny & The Starfires. However, before coming together to form Steel Mill, both Springsteen and Lopez went on to play in other bands, Springsteen formed Earth with fellow Ocean County College students, John Graham and Michael Burke. They would later be joined by another former Castile, Bob Alfano, Lopez, meanwhile, played with the Downtown Tangiers Band, which also included Bill Chinnock, Danny Federici and Garry Tallent, and then in Moment of Truth with Tallent, Federici and Ricky DeSarno. In 1968 the Upstage Club was opened at 702 Cookman Avenue in Asbury Park, the club would subsequently play a central role in the history of both Bruce Springsteen and the E Street Band and Southside Johnny & The Asbury Jukes. On February 14,1969, Lopez, looking to recruit a guitarist for a new band, saw Springsteen play with Earth at the Italian American Mens Association Clubhouse in Long Branch, New Jersey. Then on February 21, Lopez, Springsteen, Federici and Roslin got together at the Upstage, shortly afterwards Carl Tinker West, a surfboard designer and concert promoter who originally came from California, became the bands manager. From March 1969 on, Child played regularly at the Pandemonium in Wanamassa, on May 28 they opened for James Cotton at this venue. Child also played there on July 20,1969, the night of the Apollo 11 first manned moon landing, the club installed several TV monitors especially for the occasion. During the show the audience stopped watching the band and turned their attention to Neil Armstrong, as a result, the band fell out with the club management and never played there again. On November 1,1969, the band played their last show using the name Child at Virginia Commonwealth University in Richmond, Virginia. Shortly afterwards they discovered another band from Long Island, New York was also using the name and had just released an album under that name on Roulette Records. Roslin has stated that they were mistaken for the other Child during shows in Richmond. To avoid confusion with the other Child, the changed their name to Steel Mill, a name suggested by Chuck Dillon. On November 21,1969 at Randolph-Macon College in Ashland, Virginia, the band opened for Chicago, in early 1970 Steel Mill visited San Francisco and performed at The Matrix and Fillmore West, and played on the same bill as Elvin Bishop, Boz Scaggs and Grin. On February 22, they recorded three songs - Goin’ Back To Georgia, The Train Song and He’s Guilty - at the Pacific Recording Studio in San Mateo
Steel mill
39.
Cookware
–
Cookware and bakeware are types of food preparation containers, commonly found in a kitchen. Cookware comprises cooking vessels, such as saucepans and frying pans, bakeware comprises cooking vessels intended for use inside an oven. Some utensils are considered both cookware and bakeware, some choices of material also require special pre-preparation of the surface—known as seasoning—before they are used for food preparation. Both the cooking pot and lid handles can be made of the material but will mean that. In order to avoid this, handles can be made of non-heat-conducting materials, for example bakelite and it is best to avoid hollow handles because they are difficult to clean or to dry. A good cooking pot design has an edge which is what the lid lies on. The lid has an edge that avoids condensation fluid from dripping off when handling the lid or putting it down. The history of cooking vessels before the development of pottery is due to the limited archaeological evidence. The earliest pottery vessels, dating from 19, 600±400 BP, were discovered in Xianrendong Cave, Jiangxi, the pottery may have been used as cookware, manufactured by hunter-gatherers. Harvard University archaeologist Ofer Bar-Yosef reported that When you look at the pots and it is also possible to extrapolate likely developments based on methods used by latter peoples. Among the first of the believed to be used by stone age civilizations were improvements to basic roasting. Examples of similar techniques are still in use in many modern cuisines, of greater difficulty was finding a method to boil water. For people without access to heated water sources, such as hot springs. In many locations the shells of turtles or large mollusks provided a source for waterproof cooking vessels, according to Frank Hamilton Cushing, Native American cooking baskets used by the Zuni developed from mesh casings woven to stabilize gourd water vessels. He reported witnessing cooking basket use by Havasupai in 1881, roasting baskets covered with clay would be filled with wood coals and the product to be roasted. When the thus fired clay separated from the basket, it would become a usable clay roasting pan in itself and this indicates a steady progression from use of woven gourd casings to waterproof cooking baskets to pottery. Other than in other cultures, Native Americans used and still use the heat source inside the cookware. Cooking baskets are filled with hot stones and roasting pans with wood coals, Native Americans would form a basket from large leaves to boil water, according to historian and novelist Louis LAmour
Cookware
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Various commercial baking pans
Cookware
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Ancient Greek casserole and brazier, 6th/4th century BC, exhibited in the Ancient Agora Museum in
Athens, housed in the
Stoa of Attalus.
Cookware
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Two cooking pots (Grapen) from medieval Hamburg circa 1200-1400 AD
Cookware
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Kitchen in the
Uphagen's House in
Long Market,
Gdańsk,
Poland
40.
Cutlery
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Cutlery includes any hand implement used in preparing, serving, and especially eating food in the Western world. A person who makes or sells cutlery is called a cutler, the city of Sheffield in England has been famous for the production of cutlery since the 17th century and a train – the Master Cutler – running from Sheffield to London was named after the industry. Cutlery is more known as silverware or flatware in the United States. Although the term silverware is used irrespective of the composition of the utensils. The major items of cutlery in the Western world are the knife, fork, in recent times, hybrid versions of cutlery have been made combining the functionality of different eating implements, including the spork, spife, and knork or the sporf which combines all three. The word cutler derives from the Middle English word cuteler and this in turn derives from Old French coutelier which comes from coutel, the words early origins can be seen in the Latin word culter. The first documented use of the term cutler in Sheffield appeared in a 1297 tax return, a Sheffield knife was listed in the Kings possession in the Tower of London fifty years later. Several knives dating from the 14th century are on display at the Cutlers Hall in Sheffield, sterling silver is the traditional material from which good quality cutlery is made. Historically, silver had the advantage over other metals of being less chemically reactive, chemical reactions between certain foods and the cutlery metal can lead to unpleasant tastes. Gold is even less reactive than silver, but the use of gold cutlery was confined to the exceptionally wealthy, even comparatively modest households might have one or two items of silver, often silver spoons. It contained, among other items, a gravy ladle, mustard spoon. Steel was always used for more utilitarian knives, and pewter was used for some cheaper items, from the nineteenth century, electroplated nickel silver was used as a cheaper substitute for sterling silver. In 1913, the British metallurgist Harry Brearley discovered stainless steel by chance, an alternative is melchior, corrosion-resistant nickel and copper alloy, which can also sometimes contain manganese and nickle-iron. Plastic cutlery is made for use, and is frequently used outdoors for camping, excursions. Plastic cutlery is also used at fast-food or take-away outlets. Wooden disposable cutlery is available as a biodegradable alternative. Cutlery has been made in many places, in Britain, the industry became concentrated by the late 16th century in and around Birmingham and Sheffield. However, the Birmingham industry increasingly concentrated on swords, made by long cutlers, at Sheffield the trade of cutler became divided, with allied trades such as razormaker, awlbladesmith, shearsmith and forkmaker emerging and becoming distinct trades by the 18th century
Cutlery
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Silver forks and a spoon
Cutlery
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Starch-polyester disposable cutlery
Cutlery
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French travelling set of cutlery, 1550-1600,
Victoria and Albert Museum
41.
Surgical instruments
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Over time, many different kinds of surgical instruments and tools have been invented. Some surgical instruments are designed for use in surgery, while others are designed for a specific procedure or surgery. History Surgical instruments have been manufactured since the dawn of pre-history, rough trephines for performing round craniotomies were discovered in neolithic sites in many places. It is believed that they were used by shamans to release evil spirits and alleviate headaches and they are still very well preserved in several medical museums around the world. Most of these continued to be used in Medieval times. In the Renaissance and post-Renaissance era, new instruments were invented and designed. Amputation sets originated in this period, due to the severity of war-inflicted wounds by shot, grapnel. A veritable explosion of new tools occurred with the hundreds of new procedures which were developed in the 19th century. New materiais, such as steel, chrome, titanium and vanadium were available for the manufacturing of these instruments. Terms relating to this issue are atraumatic and minimally invasive, minimally invasive systems are an important recent development in surgery. Edgar R. McGuire Historical Medical Instrument Collection from the University at Buffalo Libraries
Surgical instruments
–
Various
scalpels
42.
Major appliances
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A major appliance, or domestic appliance, is a large machine in home appliance used for routine housekeeping tasks such as cooking, washing laundry, or food preservation. An appliance is different from a plumbing fixture because it uses electricity or fuel, major appliances differ from small appliances because they are bigger and not portable. They are often considered fixtures and part of estate and as such they are often supplied to tenants as part of otherwise unfurnished rental properties. Major appliances may have electrical connections, connections to gas supplies, or special plumbing. This limits where they can be placed in a home, many major appliances are made of enamel-coated sheet steel which, in the middle 20th century, was usually white. The term white goods in contrast to brown goods, is used, primarily where British English is spoken. In the United States, the white goods can also refer to linens. In New Zealand whiteware may be used, elsewhere a term from pottery, since major appliances in a home consume a significant amount of energy, they have become the objectives of programs to improve their energy efficiency in many countries. Energy efficiency improvements may require changes in construction of the appliances, in the early days of electrification, many major consumer appliances were made by the same companies that made the generation and distribution equipment
Major appliances
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A side-by side
refrigerator
Major appliances
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A modern front-loading
washing machine
Major appliances
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A
drying cabinet
43.
Sugar refinery
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A sugar refinery is a refinery which processes raw sugar into white refined sugar or that processes sugar beet to refined sugar. While cane sugar does not need refining to be palatable, sugar from sugar beet is almost always refined to remove the strong, almost always unwanted, the refined sugar produced is more than 99 percent pure sucrose. Whereas many sugar mills only operate during a time of the year during the cane harvesting period. Sugar beet refineries tend to have periods when they process beet but may store intermediate product. Raw sugar is processed into white refined sugar in local refineries. Sugar refineries are located in heavy sugar-consuming regions such as North America, Europe. Since the 1990s many state-of-the art sugar refineries have been built in the Middle East and North Africa region, e. g. in Dubai, the world´s largest sugar refinery company is American Sugar Refining with facilities in North America and Europe. The raw sugar is stored in warehouses and then transported into the sugar refinery by means of transport belts. Many sugar refineries today buy high pol sugar and can do without the affination process, the remaining sugar is then dissolved to make a syrup, which is clarified by the addition of phosphoric acid and calcium hydroxide that combine to precipitate calcium phosphate. The calcium phosphate particles entrap some impurities and absorb others, and then float to the top of the tank, after any remaining solids are filtered out, the clarified syrup is decolorized by filtration through a bed of activated carbon or, in more modern plants, ion-exchange resin. The purified syrup is concentrated to supersaturation and repeatedly crystallized under vacuum to produce white refined sugar. As in a mill, the sugar crystals are separated from the mother liquor by centrifuging. To produce granulated sugar, in which the individual grains do not clump together. Drying is accomplished first by drying the sugar in a hot rotary dryer, the finished product is stored in large concrete or steel silos. It is shipped in bulk, big bags or 25 –50 kg bags to customers or packed in consumer-size packages to retailers. The dried sugar must be handled with caution, as sugar dust explosions are possible, a sugar dust explosion which led to 13 fatalities was the 2008 Georgia sugar refinery explosion in Port Wentworth, GA. Molasses Bagasse Press Mud As in many other industries factory automation has been promoted heavily in sugar refineries in recent decades, the production process is generally controlled by a central process control system, which directly controls most of the machines and components. Only for certain special machines such as the centrifuges in the sugar house decentralized PLCs are used for security reasons
Sugar refinery
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Hawaii Commercial Sugar (HC&S) sugar mill in
Pu'unene, Hawaii.
Sugar refinery
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Sugar refinery in Arabi, Louisiana,
United States.
Sugar refinery
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Sugar refinery in
Groningen, The Netherlands
Sugar refinery
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Raw sugar storage in a sugar refinery
44.
Orange juice
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Orange juice is the liquid extract of the fruit of the orange tree, produced by squeezing oranges. It comes in different varieties, including blood orange, navel oranges, valencia orange, clementine. As well as variations in oranges used, some varieties include differing amounts of vesicles, known as pulp in American English. These vesicles contain the juice of the orange and can be left in or removed during the manufacturing process, how juicy these vesicles are depend upon many factors, such as species, variety, and season. In American English, the name may be abbreviated as OJ. Orange juice is offered to every visitor at each of the states five Florida Welcome Centers, commercial orange juice with a long shelf life is made by drying and later rehydrating the juice, or by concentrating the juice and later adding water to the concentrate. Prior to drying, the juice may also be pasteurized and oxygen removed from it, necessitating the addition of a flavor pack. The health value of orange juice is debatable and it has a high concentration of vitamin C, but also a very high concentration of simple sugars, comparable to soft drinks. As a result, some government nutritional advice has been adjusted to encourage substitution of orange juice with raw fruit, which is digested more slowly, during World War II, American soldiers rejected vitamin C-packed lemon crystals because of their unappetizing taste. Thus the government searched for a food that would fulfill the needs of the soldiers, have a desirable taste. The federal government, the Florida department of Citrus, along with a group of scientists desired to develop a product to canned orange juice. Unfortunately, frozen concentrated orange juice was developed three years after the war had ended, by 1949, orange juice processing plants in Florida were producing over 10 million gallons of concentrated orange juice. Consumers were captivated with the idea of concentrated canned orange juice as it was affordable, tasty, convenient, the preparation was simple, thaw the juice, add water, and stir. However, by the 1980s, food scientists developed a more fresh-tasting juice known as reconstituted ready to serve juice. Eventually in the 1990s, “not from concentrate” orange juice was developed, a cup serving of raw, fresh orange juice, amounting to 248 grams or 8 ounces, has 124 mg of vitamin C. It has 20.8 g of sugars and has 112 Calories and it also supplies potassium, thiamin, and folate. Citrus juices contain flavonoids that may have health benefits, Orange juice is also a source of the antioxidant hesperidin. Because of its citric acid content, orange juice is acidic, commercial squeezed orange juice is pasteurized and filtered before being evaporated under vacuum and heat
Orange juice
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A glass of pulp-free orange juice
Orange juice
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Orange juice
Orange juice
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Mexico City merchant with his freshly squeezed orange juice, March 2010
Orange juice
–
A glass of
blood orange juice
45.
Sterilization (microbiology)
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Sterilization can be achieved through various means, including, heat, chemicals, irradiation, high pressure, and filtration. Sterilization is distinct from disinfection, sanitization, and pasteurization in that kills, deactivates, or eliminates all forms of life. Canning of foods is an extension of the principle, and has helped to reduce food borne illness. Other methods of sterilizing foods include food irradiation and high pressure, in general, surgical instruments and medications that enter an already aseptic part of the body must be sterile. Examples of such instruments include scalpels, hypodermic needles and artificial pacemakers and this is also essential in the manufacture of parenteral pharmaceuticals. Most medical and surgical devices used in healthcare facilities are made of materials that are able to go under steam sterilization, however, since 1950, there has been an increase in medical devices and instruments made of materials that require low-temperature sterilization. Ethylene oxide gas has been used since the 1950s for heat-, within the past 15 years, a number of new, low-temperature sterilization systems have been developed and are being used to sterilize medical devices. ]Steam sterilization is the most widely used and the most dependable. Steam sterilization is nontoxic, inexpensive, rapidly microbicidal, sporicidal, there are strict international rules to protect the contamination of Solar System bodies from biological material from Earth. Standards vary depending on both the type of mission and its destination, the more likely a planet is considered to be habitable, the aim of sterilization is the reduction of initially present microorganisms or other potential pathogens. The degree of sterilization is commonly expressed by multiples of the decimal reduction time, or D-value, then the number of microorganisms N after sterilization time t is given by, N N0 =10. The D-value is a function of sterilization conditions and varies with the type of microorganism, temperature, water activity, for steam sterilization typically the temperature is given as index. Theoretically, the likelihood of survival of an individual microorganism is never zero, to compensate for this, the overkill method is often used. Using the overkill method, sterilization is performed by sterilizing for longer than is required to kill the present on or in the item being sterilized. This provides a sterility assurance level equal to the probability of a non-sterile unit, for high-risk applications such as medical devices and injections, a sterility assurance level of at least 10−6 is required by the United States Food and Drug Administration. A widely used method for heat sterilization is the autoclave, sometimes called a converter or steam sterilizer, autoclaves use steam heated to 121-134 °C under pressure. To achieve sterility, the article is heated in a chamber by injected steam until the article reaches a time, meantime almost all the air is removed from the chamber, because air is undesired in the moist heat sterilization process. The article is then held at that setpoint for a period of time varies depending on the bioburden present on the article being sterilized. Following sterilization, liquids in a pressurized autoclave must be cooled slowly to avoid boiling over when the pressure is released and this may be achieved by gradually depressurizing the sterilization chamber and allowing liquids to evaporate under a negative pressure, while cooling the contents
Sterilization (microbiology)
–
Joseph Lister was a pioneer of
antiseptic surgery.
Sterilization (microbiology)
–
Apparatus to sterilize surgical instruments, Verwaltungsgebäude der Schweiz. Kranken- und Hilfsanstalt, 1914-1918
Sterilization (microbiology)
–
Front-loading autoclave
Sterilization (microbiology)
–
Dry heat sterilizer
46.
Salt-water
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Seawater, or salt water, is water from a sea or ocean. On average, seawater in the oceans has a salinity of about 3. 5% This means that every kilogram of seawater has approximately 35 grams of dissolved salts. Average density at the surface is 1.025 kg/l, seawater is denser than both fresh water and pure water because the dissolved salts increase the mass by a larger proportion than the volume. The freezing point of seawater decreases as salt concentration increases, at typical salinity, it freezes at about −2 °C. The coldest seawater ever recorded was in 2010, in a stream under an Antarctic glacier, seawater pH is typically limited to a range between 7.5 and 8.4. However, there is no universally accepted reference pH-scale for seawater, although the vast majority of seawater has a salinity of between 31 g/kg and 38 g/kg, seawater is not uniformly saline throughout the world. Where mixing occurs with fresh water runoff from river mouths, near melting glaciers or vast amounts precipitation, the most saline open sea is the Red Sea, where high rates of evaporation, low precipitation and low river run-off, and confined circulation result in unusually salty water. The salinity in isolated bodies of water can be considerably greater still, historically, several salinity scales were used to approximate the absolute salinity of seawater. A popular scale was the Practical Salinity Scale where salinity was measured in practical salinity units, the current standard for salinity is the Reference Salinity scale with the salinity expressed in units of g/kg. The density of surface seawater ranges from about 1020 to 1029 kg/m3, depending on the temperature, at a temperature of 25 °C, salinity of 35 g/kg and 1 atm pressure, the density of seawater is 1023.6 kg/m3. Deep in the ocean, under pressure, seawater can reach a density of 1050 kg/m3 or higher. The density of seawater also changes with salinity, brines generated by seawater desalination plants can have salinities up to 120 g/kg. The density of typical seawater brine of 120 g/kg salinity at 25 °C, seawater pH is limited to the range 7.5 to 8.4. The speed of sound in seawater is about 1,500 m/s, and varies with temperature, salinity. The thermal conductivity of seawater is 0.6 W/mK at 25 °C, the thermal conductivity decreases with increasing salinity and increases with increasing temperature. Seawater contains more dissolved ions than all types of freshwater, however, the ratios of solutes differ dramatically. Bicarbonate ions also constitute 48% of river water solutes but only 0. 14% of all seawater ions, differences like these are due to the varying residence times of seawater solutes, sodium and chlorine have very long residence times, while calcium tends to precipitate much more quickly. The most abundant dissolved ions in seawater are sodium, chloride, magnesium, sulfate and its osmolarity is about 1000 mOsm/l
Salt-water
–
Seawater in the
Strait of Malacca
47.
Aluminium-bronze
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Aluminium bronze is a type of bronze in which aluminium is the main alloying metal added to copper, in contrast to standard bronze or brass. The following table lists the most common standard aluminium bronze wrought alloy compositions, the percentages show the proportional composition of the alloy by weight. Copper is the remainder by weight and is not listed, Aluminium bronzes are most valued for their higher strength and they are also resistant to corrosion in sea water. The addition of tin can improve corrosion resistance, another notable property of aluminium bronzes are their biostatic effects. Aluminium bronzes tend to have a golden color, Aluminium bronzes are most commonly used in applications where their resistance to corrosion makes them preferable to other engineering materials. These applications include plain bearings and landing gear components on aircraft, guitar strings, engine components, underwater fastenings in naval architecture, Aluminium bronze is also used to fulfil the ATEX directive for Zones 1,2,21, and 22. The attractive gold-toned coloration of aluminium bronzes has also led to their use in jewellery, Aluminium bronze is used to replace gold for the casting of dental crowns. The alloys used are chemically inert and have the appearance of gold, publication Number 80, Aluminium Bronze Alloys Corrosion Resistance Guide, PDF. Publication Number 82, Aluminium Bronze Alloys Technical Data
Aluminium-bronze
–
Aluminium bronze with 20% Aluminium at 500x magnification
48.
Copper-nickel
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Cupronickel is an alloy of copper that contains nickel and strengthening elements, such as iron and manganese. Despite its high content, cupronickel is silver in colour. Cupronickel is highly resistant to corrosion in seawater because its potential is adjusted to be neutral with regard to seawater. Another common use of cupronickel is in silver-coloured modern-circulated coins, a typical mix is 75% copper, 25% nickel, and a trace amount of manganese. In the past, true silver coins were debased with cupronickel, Cupronickel alloys are used for marine applications due to their resistance to seawater corrosion, good fabricability, and their effectiveness in lowering macrofouling levels. Alloys ranging in composition from 90% Cu–10% Ni to 70% Cu–30% Ni are commonly specified in heat exchanger or condenser tubes in a variety of marine applications. Desalination plants, Cupronickel alloys are used in brine heaters, heat rejection and recovery, offshore oil and gas platforms and processing and FPSO vessels, Cupronickel alloys are used in systems and splash zone sheathings. Power generation, Cupronickel alloys are used in steam turbine condensers, oil coolers, auxiliary cooling systems and high pressure pre-heaters at nuclear, seawater system design, Cupronickel alloys are used in tubular heat exchangers and condensers, piping and high pressure systems. Seawater system components, Cupronickel alloys are used in condenser and heat exchanger tubes, tubesheets, piping, fittings, pumps, in Europe, Switzerland pioneered the nickel billon coinage in 1850, with the addition of silver. In 1968, Switzerland adopted the far cheaper 75,25 copper to nickel ratio then being used by the Belgians, the United States, and Germany. From 1947 to 2012, all “silver” coinage in the UK was made from cupronickel, prior to these dates, both denominations had been made only in silver in the United States. Cupronickel is the cladding on either side of United States half-dollars since 1971, currently, some circulating coins, such as the United States Jefferson nickel, the Swiss franc, and the South Korean 500 and 100 won are made of solid cupronickel. Single-core thermocouple cables use a single pair of thermocouple conductors such as iron-constantan. These have the element of constantan or nickel-chromium alloy within a sheath of copper. Cupronickel is used in cryogenic applications, beginning around the turn of the 20th century, bullet jackets were commonly made from this material. It was soon replaced with gilding metal to reduce fouling in the bore. Currently, cupronickel remains the basic material for silver-plated cutlery and it is commonly used for mechanical and electrical equipment, medical equipment, zippers, jewelry items, and as material for strings for string instruments. Fender Musical Instruments used CuNiFe magnets in their Wide Range Humbucker pickup for various Telecaster and Starcaster guitars during the 1970s, for high-quality cylinder locks and locking systems, cylinder cores are made from wear-resistant cupronickel
Copper-nickel
–
Five Swiss francs
Copper-nickel
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Crack in 90-10 Cu-Ni metal plate due to stresses during silver brazing
49.
Desalination
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Desalination is a process that extracts minerals from saline water. More generally, desalination refers to the removal of salts and minerals from a substance, as in soil desalination. Saltwater is desalinated to produce water suitable for consumption or irrigation. One by-product of desalination is salt, Desalination is used on many seagoing ships and submarines. Most of the modern interest in desalination is focused on cost-effective provision of water for human use. Along with recycled wastewater, it is one of the few rainfall-independent water sources, due to its energy consumption, desalinating sea water is generally more costly than fresh water from rivers or groundwater, water recycling and water conservation. However, these alternatives are not always available and depletion of reserves is a problem worldwide. Currently, approximately 1% of the population is dependent on desalinated water to meet daily needs. Desalination is particularly relevant in dry countries such as Australia, which traditionally have relied on collecting rainfall behind dams for water and this number increased from 78.4 million cubic meters in 2013, a 10. 71% increase in 2 years. Kuwait produces a higher proportion of its water than any other country, the traditional process used in these operations is vacuum distillation—essentially boiling it to leave impurities behind. In desalination, atmospheric pressure is reduced, thus lowering the temperature needed. Liquids boil when the pressure equals the ambient pressure and vapor pressure increases with temperature. Thus, because of the temperature, low-temperature waste heat from electrical power generation or industrial processes can be employed. Water is evaporated and separated from sea water through multi-stage flash distillation, each subsequent flash process utilizes energy released from the condensation of the water vapor from the previous step. Multiple effect distillation works through a series of steps called “effects”, incoming water is sprayed onto vertically or, more commonly, horizontally oriented pipes which are then heated to generate steam. The steam is used to heat the next batch of incoming sea water. To increase efficiency, the used to heat the sea water can be taken from nearby power plants. Although this method is the most thermodynamically efficient, a few limitations exist such as a max temperature, vapor compression distillation involves using either a mechanical compressor or a jet stream to compress the vapor present above the liquid
Desalination
–
Reverse osmosis desalination plant in Barcelona, Spain
Desalination
–
Plan of a typical
reverse osmosis desalination plant
Desalination
–
The Shevchenko BN350, a nuclear-heated desalination unit
Desalination
–
RO production train, North Cape Coral RO Plant
50.
Temperature
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A temperature is an objective comparative measurement of hot or cold. It is measured by a thermometer, several scales and units exist for measuring temperature, the most common being Celsius, Fahrenheit, and, especially in science, Kelvin. Absolute zero is denoted as 0 K on the Kelvin scale, −273.15 °C on the Celsius scale, the kinetic theory offers a valuable but limited account of the behavior of the materials of macroscopic bodies, especially of fluids. Temperature is important in all fields of science including physics, geology, chemistry, atmospheric sciences, medicine. The Celsius scale is used for temperature measurements in most of the world. Because of the 100 degree interval, it is called a centigrade scale.15, the United States commonly uses the Fahrenheit scale, on which water freezes at 32°F and boils at 212°F at sea-level atmospheric pressure. Many scientific measurements use the Kelvin temperature scale, named in honor of the Scottish physicist who first defined it and it is a thermodynamic or absolute temperature scale. Its zero point, 0K, is defined to coincide with the coldest physically-possible temperature and its degrees are defined through thermodynamics. The temperature of zero occurs at 0K = −273. 15°C. For historical reasons, the triple point temperature of water is fixed at 273.16 units of the measurement increment, Temperature is one of the principal quantities in the study of thermodynamics. There is a variety of kinds of temperature scale and it may be convenient to classify them as empirically and theoretically based. Empirical temperature scales are historically older, while theoretically based scales arose in the middle of the nineteenth century, empirically based temperature scales rely directly on measurements of simple physical properties of materials. For example, the length of a column of mercury, confined in a capillary tube, is dependent largely on temperature. Such scales are only within convenient ranges of temperature. For example, above the point of mercury, a mercury-in-glass thermometer is impracticable. A material is of no use as a thermometer near one of its phase-change temperatures, in spite of these restrictions, most generally used practical thermometers are of the empirically based kind. Especially, it was used for calorimetry, which contributed greatly to the discovery of thermodynamics, nevertheless, empirical thermometry has serious drawbacks when judged as a basis for theoretical physics. Theoretically based temperature scales are based directly on theoretical arguments, especially those of thermodynamics, kinetic theory and they rely on theoretical properties of idealized devices and materials
Temperature
–
Annual mean temperature around the world
Temperature
–
Body temperature variation
Temperature
–
A typical Celsius thermometer measures a winter day temperature of -17 °C.
Temperature
–
Plots of pressure vs temperature for three different gas samples extrapolated to absolute zero.
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