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. As construction finished in the spring of 2003, the Philharmonic postponed its opening until the fall and used the summer to let the orchestra. Performers and critics agreed that it was 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
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
3.
Allotropes of iron
–
Iron represents perhaps the best-known example for allotropy in a metal. At atmospheric pressure, there are three forms of iron, alpha iron a. k. a. ferrite, gamma iron a. k. a. austenite. At very high pressure, a form exists, called epsilon iron hexaferrum. Some controversial experimental evidence exists for another form that is stable at very high pressures and temperatures. The phases of iron at atmospheric pressure are important because of the differences in solubility of carbon, the high-pressure phases of iron are important as models for the solid parts of planetary cores. The inner core of the Earth is generally assumed to consist essentially of a crystalline iron-nickel alloy with ε structure, the outer core surrounding the solid inner core is believed to be composed of liquid iron mixed with nickel and trace amounts of lighter elements. As molten iron cools down, it solidifies at 1,538 °C into its δ allotrope, δ-iron can dissolve as much as 0. 09% of carbon by mass at 1,493 °C. As the iron cools further to 1,394 °C its crystal structure changes to a face centered cubic crystalline structure, in this form it is called gamma iron or Austenite. γ-iron can dissolve considerably more carbon and this γ form of carbon saturation is exhibited in stainless steel. Beta ferrite and beta iron are obsolete terms for the form of ferrite. The primary phase of low-carbon or mild steel and most cast irons at room temperature is ferromagnetic ferrite, the A2 forms the low-temperature boundary of the beta iron field in the phase diagram in Figure 1. For this reason, the phase is not usually considered a distinct phase. At 912 °C the crystal structure again becomes BCC as α-iron is formed, the substance assumes a paramagnetic property. α-iron can dissolve only a small concentration of carbon, at 770 °C, the Curie point, the iron is a fairly soft metal and becomes ferromagnetic. As the iron passes through the Curie temperature there is no change in crystalline structure and this is the stable form of iron at room temperature. Antiferromagnetism in alloys of epsilon-Fe with Mn, Os and Ru has been observed. An alternate stable form, if it exists, may appear at pressures of at least 50 GPa and temperatures of at least 1,500 K, as of December 2011, recent and ongoing experiments are being conducted on high-pressure and Superdense carbon allotropes. Superdense carbon allotropes Allotropy Austenite Curie point Eutectic system Ferrite Tempering
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
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
6.
Graphite
–
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
7.
Martensite
–
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
8.
Microstructure
–
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
9.
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
10.
Pearlite
–
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
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
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
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
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
15.
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
16.
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
17.
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
18.
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
19.
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
20.
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
21.
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
22.
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
23.
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%
24.
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
25.
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
26.
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
27.
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
28.
Molybdenum
–
Molybdenum is a chemical element with symbol Mo and atomic number 42. The name is from Neo-Latin molybdaenum, from Ancient Greek Μόλυβδος molybdos, meaning lead, molybdenum minerals have been known throughout history, but the element was discovered in 1778 by Carl Wilhelm Scheele. The metal was first isolated in 1781 by Peter Jacob Hjelm, molybdenum does not occur naturally as a free metal on Earth, it is found only in various oxidation states in minerals. The free element, a metal with a gray cast, has the sixth-highest melting point of any element. It readily forms hard, stable carbides in alloys, and for this reason most of production of the element is used in steel alloys. Most molybdenum compounds have low solubility in water, but when molybdenum-bearing minerals contact oxygen and water, industrially, molybdenum compounds are used in high-pressure and high-temperature applications as pigments and catalysts. Molybdenum-bearing enzymes are by far the most common catalysts for breaking the chemical bond in atmospheric molecular nitrogen in the process of biological nitrogen fixation. At least 50 molybdenum enzymes are now known in bacteria and animals and these nitrogenases contain molybdenum in a form different from other molybdenum enzymes, which all contain fully oxidized molybdenum in a molybdenum cofactor. These various molybdenum cofactor enzymes are vital to the organisms, and molybdenum is an element for life in all higher eukaryote organisms. In its pure form, molybdenum is a metal with a Mohs hardness of 5.5. It has a point of 2,623 °C, of the naturally occurring elements, only tantalum, osmium, rhenium, tungsten. Weak oxidation of molybdenum starts at 300 °C and it has one of the lowest coefficients of thermal expansion among commercially used metals. The tensile strength of molybdenum wires increases about 3 times, from about 10 to 30 GPa, there are 35 known isotopes of molybdenum, ranging in atomic mass from 83 to 117, as well as four metastable nuclear isomers. Seven isotopes occur naturally, with masses of 92,94,95,96,97,98. Of these naturally occurring isotopes, only molybdenum-100 is unstable, molybdenum-98 is the most abundant isotope, comprising 24. 14% of all molybdenum. Molybdenum-100 has a half-life of about 1019 y and undergoes double beta decay into ruthenium-100, molybdenum isotopes with mass numbers from 111 to 117 all have half-lives of approximately 150 ns. All unstable isotopes of molybdenum decay into isotopes of niobium, technetium, as also noted below, the most common isotopic molybdenum application involves molybdenum-99, which is a fission product. It is a parent radioisotope to the short-lived gamma-emitting daughter radioisotope technetium-99m, in 2008, the Delft University of Technology applied for a patent on the molybdenum-98-based production of molybdenum-99
29.
Sheet metal
–
Sheet metal is metal formed by an industrial process into thin, flat pieces. It is one of the forms used in metalworking and it can be cut. Countless everyday objects are fabricated from sheet metal, thicknesses can vary significantly, extremely thin thicknesses are considered foil or leaf, and pieces thicker than 6 mm are considered plate. Sheet metal is available in flat pieces or coiled strips, the coils are formed by running a continuous sheet of metal through a roll slitter. The thickness of metal is in the USA commonly specified by a traditional. The larger the number, the thinner the metal. Commonly used steel sheet metal ranges from 30 gauge to about 7 gauge, in the rest of the world, the sheet metal thickness is given in millimeters. There are many different metals that can be made into metal, such as aluminium, brass, copper, steel, tin, nickel. Sheet metal of iron and other materials with high permeability, also known as laminated steel cores, has applications in transformers. Historically, an important use of metal was in plate armor worn by cavalry. Sheet metal workers are known as tin bashers, a name derived from the hammering of panel seams when installing tin roofs. Grade 304 is the most common of the three grades and it offers good corrosion resistance while maintaining formability and weldability. Available finishes are #2B, #3, and #4, grade 303 is not available in sheet form. Grade 316 possesses more corrosion resistance and strength at elevated temperatures than 304 and it is commonly used for pumps, valves, chemical equipment, and marine applications. Available finishes are #2B, #3, and #4, grade 410 is a heat treatable stainless steel, but it has a lower corrosion resistance than the other grades. It is commonly used in cutlery, the only available finish is dull. Grade 430 is popular grade, low cost alternative to series 300s grades, used when high corrosion resistance is not a primary criteria. Common grade for appliance products, often with a brushed finish, aluminum is also a popular metal used in sheet metal due to its flexibility, wide range of options, cost effectiveness, and other properties
30.
Cookware and bakeware
–
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
31.
Cutlery
–
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
32.
Surgical instrument
–
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
33.
Major appliance
–
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
34.
Chrysler Building
–
At 1,046 feet, the structure was the worlds tallest building for 11 months before it was surpassed by the Empire State Building in 1931. It is the tallest brick building in the world, with a steel structure, in addition, The New York Times Building, which opened in 2007, is exactly level with the Chrysler Building in height. The Chrysler Building is an example of Art Deco architecture. In 2007, it was ranked ninth on the List of Americas Favorite Architecture by the American Institute of Architects and it was the headquarters of the Chrysler Corporation from 1930 until the mid-1950s. Although the building was built and designed specifically for the car manufacturer, Chrysler decided to pay for it himself, so that his children could inherit it. The Chrysler Building was designed by architect William Van Alen for a project of Walter P. Chrysler, when the ground breaking occurred on September 19,1928, there was an intense competition in New York City to build the worlds tallest skyscraper. Despite a frantic pace, no workers died during the construction of this skyscraper, Van Alens original design for the skyscraper called for a decorative jewel-like glass crown. It also featured a base in which the windows were tripled in height and topped by 12 stories with glass-wrapped corners. The height of the skyscraper was originally designed to be 246 meters. However, the proved to be too advanced and costly for building contractor William H. Reynolds. The design and lease were then sold to Walter P. Chrysler, construction commenced on September 19,1928. In total,391,881 rivets were used and approximately 3,826,000 bricks were manually laid, contractors, builders and engineers were joined by other building-services experts to coordinate construction. Prior to its completion, the building stood about even with a project at 40 Wall Street. Severance increased the height of his project and then claimed the title of the worlds tallest building. In response, Van Alen obtained permission for a 38-meter long spire and had it secretly constructed inside the frame of the building, the spire was delivered to the site in four different sections. On October 23,1929, the section of the spire was hoisted to the top of the buildings dome. The other remaining sections of the spire were hoisted and riveted to the first one in order in just 90 minutes. It was the first man-made structure to stand taller than 1,000 feet, Van Alens satisfaction in these accomplishments was likely muted by Walter Chryslers later refusal to pay the balance of his architectural fee
35.
Paper mill
–
A paper mill is a factory devoted to making paper from vegetable fibres such as wood pulp, old rags and other ingredients. While the use of human and animal powered mills was known to Chinese and Muslim papermakers, the general absence of the use of water-power in Muslim papermaking is suggested by the habit of Muslim authors to call a production center not a mill, but a paper manufactory. Although scholars have identified paper mills in Abbasid-era Baghdad in 794–795, in the Moroccan city of Fez, Ibn Battuta speaks of 400 mill stones for paper. Since Ibn Battuta does not mention the use of water-power and such a number of water-mills would be grotesquely high, the passage is generally taken to refer to human or animal force. An exhaustive survey of milling in Al-Andalus did not uncover a single water-powered paper mill, Burns remains altogether sceptical given the isolated occurrence of the reference and the prevalence of manual labour in Islamic papermaking elsewhere. Likewise, the identification of early hydraulic stamping mills in medieval documents from Fabriano, the earliest certain evidence to a water-powered paper mill dates to 1282 in the Spanish Kingdom of Aragon. A decree by the Christian king Peter III addresses the establishment of a royal molendinum, the first permanent paper mill north of the Alps was established in Nuremberg by Ulman Stromer in 1390, it is later depicted in the lavishly illustrated Nuremberg Chronicle. From the mid-14th century onwards, European paper milling underwent an improvement of many work processes. The size of a paper mill prior to the use of machines was described by counting the number of vats it had. Thus, a one vat paper mill had only one vatman, one coucher, by the early 20th century, paper mills sprang up around New England and the rest of the world, due to the high demand for paper. At this time, there were many leaders of the production of paper, one of such was the Brown Company in Berlin. During the year 1907, the Brown Company cut between 30 and 40 million acres of woodlands on their property, which extended from La Tuque, Quebec, Canada to West Palm, “Log drives” were conducted on local rivers to send the logs to the mills. By the late 20th and early 21st-century, paper began to close. Due to the addition of new machinery, many millworkers were laid off, Paper mills can be fully integrated mills or nonintegrated mills. Integrated mills consist of a mill and a paper mill on the same site. Such mills receive logs or wood chips and produce paper, modern paper machines can be 500 feet in length, produce a sheet 400 inches wide, and operate at speeds of more than 60 miles per hour. The two main suppliers of paper machines are Metso and Voith, Paper pollution Cutting stock problem List of paper mills Burns, Robert I. Paper comes to the West, 800−1400, in Lindgren, Uta, mann Verlag, pp. biz - Paper world directory and search engine for the pulp and paper world List of paper mills on paper and print monthly
36.
Chemical plant
–
A chemical plant is an industrial process plant that manufactures chemicals, usually on a large scale. The general objective of a plant is to create new material wealth via the chemical or biological transformation. Chemical plants use specialized equipment, units, and technology in the manufacturing process, some would consider an oil refinery or a pharmaceutical or polymer manufacturer to be effectively a chemical plant. Petrochemical plants are located adjacent to an oil refinery to minimize transportation costs for the feedstocks produced by the refinery. Speciality chemical and fine chemical plants are much smaller and not as sensitive to location. Tools have been developed for converting a base project cost from one location to another. Chemical plants use chemical processes, which are detailed industrial-scale methods, the same chemical process can be used at more than one chemical plant, with possibly differently scaled capacities at each plant. Also, a plant at a site may be constructed to utilize more than one chemical process. A chemical plant commonly has usually large vessels or sections called units or lines that are interconnected by piping or other material-moving equipment which can carry streams of material, such material streams can include fluids or sometimes solids or mixtures such as slurries. An overall chemical process is made up of steps called unit operations which occur in the individual units. A raw material going into a process or plant as input to be converted into a product is commonly called a feedstock. In addition to feedstocks for the plant as a whole, a stream of material to be processed in a particular unit can similarly be considered feed for that unit. Output streams from the plant as a whole are final products, however, final products from one plant may be intermediate chemicals used as feedstock in another plant for further processing. For example, some products from an oil refinery may used as feedstock in petrochemical plants, either the feedstock, the product, or both may be individual compounds or mixtures. It is often not worthwhile separating the components in these mixtures completely, specific levels of purity depend on product requirements, chemical processes may be run in continuous or batch operation. In batch operation, production occurs in time-sequential steps in discrete batches, a batch of feedstock is fed into a process or unit, then the chemical process takes place, then the product and any other outputs are removed. Such batch production may be repeated again and again with new batches of feedstock. Batch operation is used in smaller scale plants such as pharmaceutical or specialty chemicals production
37.
Water treatment
–
Water treatment is any process that makes water more acceptable for a specific end-use. The end use may be drinking, industrial supply, irrigation, river flow maintenance, water recreation or many other uses. Water treatment removes contaminants and undesirable components, or reduces their concentration so that the water becomes fit for its desired end-use. Substances that are removed during the process of drinking water treatment include suspended solids, bacteria, algae, viruses, fungi, measures taken to ensure water quality not only relate to the treatment of the water, but to its conveyance and distribution after treatment. It is therefore common practice to keep residual disinfectants in the water to kill bacteriological contamination during distribution. World Health Organization guidelines are a set of standards intended to apply where better local standards are not implemeted. More rigorous standards apply across Europe, the USA and in most other developed countries, followed throughout the world for drinking water quality requirements. Disinfection for killing bacteria viruses and other pathogens, technologies for potable water and other uses are well developed, and generalized designs are available from which treatment processes can be selected for pilot testing on the specific source water. In addition, a number of companies provide patented technological solutions for treatment of specific contaminants. Automation of water and waste-water treatment is common in the developed world, source water quality through the seasons, scale and environmental impact can dictate capital costs and operating costs. End use of the treated water dictates the necessary quality monitoring technologies, biological processes can be employed in the treatment of wastewater and these processes may include, for example, aerated lagoons, activated sludge or slow sand filters. To be effective, sewage must be conveyed to a treatment plant by appropriate pipes and infrastructure, some wastewaters require different and sometimes specialized treatment methods. At the simplest level, treatment of sewage and most wastewaters is carried out through separation of solids from liquids, by progressively converting dissolved material into solids, usually a biological floc, which is then settled out, an effluent stream of increasing purity is produced. Two of the processes of industrial water treatment are boiler water treatment. A lack of water treatment can lead to the reaction of solids and bacteria within pipe work. Steam boilers can suffer from scale or corrosion when left untreated, scale deposits can lead to weak and dangerous machinery, while additional fuel is required to heat the same level of water because of the rise in thermal resistance. Poor quality dirty water can become a ground for bacteria such as Legionella causing a risk to public health. With the proper treatment, a significant proportion of industrial on-site wastewater might be reusable, corrosion in low pressure boilers can be caused by dissolved oxygen, acidity and excessive alkalinity
38.
Chemical tanker
–
A chemical tanker is a type of tanker ship designed to transport chemicals in bulk. As defined in MARPOL Annex II, chemical tanker means a ship constructed or adapted for carrying in any liquid product listed in chapter 17 of the International Bulk Chemical Code. Chemical tankers normally have a series of cargo tanks which are either coated with specialized coatings such as phenolic epoxy or zinc paint. The coating or tank material also influences how quickly tanks can be cleaned, typically, ships with stainless steel tanks can carry a wider range of cargoes and can clean more quickly between one cargo and another, which justifies the additional cost of their construction. Most chemical tankers are IMO2 and 3 rated, since the volume of IMO1 cargoes is very limited, consequently, many oceangoing chemical tankers may carry numerous different grades of cargo on the same voyage, often loading and discharging these parcels at different ports or terminals. This means that the scheduling, stowage planning and operation of such ships requires a level of coordination and specialist knowledge. Before tanks are cleaned, they must be ventilated and checked to be free of potentially explosive gases. Cargo tanks, either empty or filled, are protected against explosion by inert gas blankets. Often nitrogen is the gas used, supplied either from portable gas bottles or a Nitrogen generator. Most new chemical tankers are built by shipbuilders in Japan, Korea or China, with other builders in Turkey, Italy, Germany, notable major chemical tanker operators include Stolt-Nielsen, Odfjell, Navig8 and Mitsui O. S. K. Charterers, the end users of the ships, include oil majors, industrial consumers, ship transport List of tankers IBC Code
39.
Tank truck
–
A tank truck or tanker truck or tanker, is a motor vehicle designed to carry liquefied loads, dry bulk cargo or gases on roads. The largest such vehicles are similar to railroad cars which are also designed to carry liquefied loads. Many variants exist due to the variety of liquids that can be transported. Tank trucks tend to be large, they may be insulated or non-insulated, pressurized or non-pressurized and they are difficult to drive due to their high center of gravity. Tank trucks are described by their size or volume capacity, large trucks typically have capacities ranging from 5,500 to 11,600 US gallons. In Australia, road trains up to three cars long carry loads in excess of 100,000 L, longer road trains transporting liquids are also in use. A tank truck is distinguished by its shape, usually a cylindrical tank upon the vehicle lying horizontally, the tanks themselves will almost always contain multiple compartments or baffles to prevent load movement destabilizing the vehicle. Large tank trucks are used for example to transport gasoline to filling stations and they also transport a wide variety of liquid goods such as liquid sugar, molasses, milk, wine, juices, water, gasoline, diesel, and industrial chemicals. Tank trucks are constructed of materials depending on what products they are hauling. These materials include aluminium, carbon steel, stainless steel, some tank trucks are able to carry multiple products at once due to compartmentalization of the tank into 2,3,4,5,6 or in some rare cases more tank compartments. This allows for an number of delivery options. These trucks are used to carry different grades of gasoline to service stations to carry all products needed in one trip. Smaller tank trucks, with a capacity of less than 3,000 US gallons are typically used to deal with light liquid cargo within a local community. A common example is vacuum truck used to empty several septic tanks and these tank trucks typically have a maximum capacity of 3,000 US gallons. They are equipped with a system to serve their particular need. Another common use is to deliver fuel such as liquified petroleum gas to households, the smallest of these trucks usually carry about 1,000 US gallons of LPG under pressure. Typically LPG tank trucks carry up to 3499 US gallons of product,3500 US gallons and greater requires a 3 axle truck. Tank trucks are used to fuel aircraft at airports
40.
Kitchen
–
A kitchen is a room or part of a room used for cooking and food preparation in a dwelling or in a commercial establishment. Many households have an oven, a dishwasher and other electric appliances. The main function of a kitchen is serving as a location for storing, cooking and preparing food, commercial kitchens are found in restaurants, cafeterias, hotels, hospitals, educational and workplace facilities, army barracks, and similar establishments. These kitchens are generally larger and equipped with bigger and more heavy-duty equipment than a residential kitchen, for example, a large restaurant may have a huge walk-in refrigerator and a large commercial dishwasher machine. Commercial kitchens are generally subject to public health laws and they are inspected periodically by public-health officials, and forced to close if they do not meet hygienic requirements mandated by law. The evolution of the kitchen is linked to the invention of the range or stove. Food was cooked over an open fire, technical advances in heating food in the 18th and 19th centuries changed the architecture of the kitchen. Before the advent of modern pipes, water was brought from a source such as wells. The houses in Ancient Greece were commonly of the atrium-type, the rooms were arranged around a courtyard for women. In many such homes, a covered but otherwise open patio served as the kitchen, homes of the wealthy had the kitchen as a separate room, usually next to a bathroom, both rooms being accessible from the court. In such houses, there was often a small storage room in the back of the kitchen used for storing food. In the Roman Empire, common folk in cities often had no kitchen of their own, some had small mobile bronze stoves, on which a fire could be lit for cooking. Wealthy Romans had relatively well-equipped kitchens, the fireplace was typically on the floor, placed at a wall—sometimes raised a little bit—such that one had to kneel to cook. Early medieval European longhouses had a fire under the highest point of the building. The kitchen area was between the entrance and the fireplace, in wealthy homes there was typically more than one kitchen. In some homes there were upwards of three kitchens, the kitchens were divided based on the types of food prepared in them. In place of a chimney, these buildings had a hole in the roof through which some of the smoke could escape. Besides cooking, the fire served as a source of heat
41.
Seawater
–
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
42.
Aluminium-bronze
–
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
43.
Cupronickel
–
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
44.
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
45.
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
46.
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
47.
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
_002.jpg)
