In metallurgy, stainless steel known as inox steel or inox from French inoxydable, is a steel alloy, with highest percentage contents of iron and nickel, with a minimum of 10.5% chromium content by mass and a maximum of 1.2% carbon by mass. Stainless steels are most notable for their corrosion resistance, which increases with increasing chromium content. Additions of molybdenum increase corrosion resistance in reducing acids and against pitting attack in chloride solutions. Thus, there are numerous grades of stainless steel with varying chromium and molybdenum contents to suit the environment the alloy must endure. Stainless steel's resistance to corrosion and staining, low maintenance, familiar luster make it an ideal material for many applications where both the strength of steel and corrosion resistance are required. Stainless steels are rolled into sheets, bars and tubing to be used in: cookware, surgical instruments, major appliances. Stainless steel's corrosion resistance, the ease with which it can be steam cleaned and sterilized, no need for surface coatings has influenced its use in commercial kitchens and food processing plants.
Stainless steels do not suffer uniform corrosion, like carbon steel, when exposed to wet environments. Unprotected carbon steel rusts when exposed to the combination of air and moisture; the resulting iron oxide surface layer is fragile. Since iron oxide occupies a larger volume than the original steel this layer expands and tends to flake and fall away exposing the underlying steel to further attack. In comparison, stainless steels contain sufficient chromium to undergo passivation, spontaneously forming a microscopically thin inert surface film of chromium oxide by reaction with the oxygen in air and the small amount of dissolved oxygen in water; this passive film prevents further corrosion by blocking oxygen diffusion to the steel surface and thus prevents corrosion from spreading into the bulk of the metal. This film is self-repairing if it is scratched or temporarily disturbed by an upset condition in the environment that exceeds the inherent corrosion resistance of that grade; the resistance of this film to corrosion depends upon the chemical composition of the stainless steel, chiefly the chromium content.
Corrosion of stainless steels can occur. It is customary to distinguish between 4 forms of corrosion: uniform, galvanic and SCC. Uniform corrosion takes place in aggressive environments chemical production or use and paper industries, etc; the whole surface of the steel is attacked and the corrosion is expressed as corrosion rate in mm/year Corrosion tables provide guidelines This is the case when stainless steels are exposed to acidic or basic solutions. Whether a stainless steel corrodes depends on the kind and concentration of acid or base, the solution temperature. Uniform corrosion is easy to avoid because of extensive published corrosion data or easy to perform laboratory corrosion testing. However, stainless steels are susceptible to localized corrosion under certain conditions, which need to be recognized and avoided; such localized corrosion is problematic for stainless steels because it is unexpected and difficult to predict. Acidic solutions can be categorized into two general categories, reducing acids such as hydrochloric acid and dilute sulfuric acid, oxidizing acids such as nitric acid and concentrated sulfuric acid.
Increasing chromium and molybdenum contents provide increasing resistance to reducing acids, while increasing chromium and silicon contents provide increasing resistance to oxidizing acids. Sulfuric acid is one of the largest tonnage industrial chemical manufactured. At room temperature Type 304 is only resistant to 3% acid while Type 316 is resistant to 3% acid up to 50 °C and 20% acid at room temperature, thus Type 304 is used in contact with sulfuric acid. Type 904L and Alloy 20 are resistant to sulfuric acid at higher concentrations above room temperature. Concentrated sulfuric acid possesses oxidizing characteristics like nitric acid and thus silicon bearing stainless steels find application. Hydrochloric acid will damage any kind of stainless steel, should be avoided. All types of stainless steel resist attack from phosphoric acid and nitric acid at room temperature. At high concentration and elevated temperature attack will occur and higher alloy stainless steels are required. In general, organic acids are less corrosive than mineral acids such as hydrochloric and sulfuric acid.
As the molecular weight of organic acids increase their corrosivity decreases. Formic acid is a strong acid. Type 304 can be used with formic acid. Acetic acid is the most commercially important of the organic acids and Type 316 is used for storing and handling acetic acid. Stainless steels Type 304 and 316 are unaffected by any of the weak bases such as ammonium hydroxide in high concentrations and at high temperatures; the same grades of stainless exposed to stronger bases such as sodium hydroxide at high concentrations and high temperatures will experience some etching and cracking. Increasing chromium and nickel contents provide increasing resistance. All grades resist damage from aldehydes and amines, though in the latter
Mercury is a chemical element with symbol Hg and atomic number 80. It is known as quicksilver and was named hydrargyrum. A heavy, silvery d-block element, mercury is the only metallic element, liquid at standard conditions for temperature and pressure. Mercury occurs in deposits throughout the world as cinnabar; the red pigment vermilion is obtained by synthetic mercuric sulfide. Mercury is used in thermometers, manometers, sphygmomanometers, float valves, mercury switches, mercury relays, fluorescent lamps and other devices, though concerns about the element's toxicity have led to mercury thermometers and sphygmomanometers being phased out in clinical environments in favor of alternatives such as alcohol- or galinstan-filled glass thermometers and thermistor- or infrared-based electronic instruments. Mechanical pressure gauges and electronic strain gauge sensors have replaced mercury sphygmomanometers. Mercury remains in use in scientific research applications and in amalgam for dental restoration in some locales.
It is used in fluorescent lighting. Electricity passed through mercury vapor in a fluorescent lamp produces short-wave ultraviolet light, which causes the phosphor in the tube to fluoresce, making visible light. Mercury poisoning can result from exposure to water-soluble forms of mercury, by inhalation of mercury vapor, or by ingesting any form of mercury. Mercury is a silvery-white liquid metal. Compared to other metals, it is a fair conductor of electricity, it has a freezing point of −38.83 °C and a boiling point of 356.73 °C, both the lowest of any stable metal, although preliminary experiments on copernicium and flerovium have indicated that they have lower boiling points. Upon freezing, the volume of mercury decreases by 3.59% and its density changes from 13.69 g/cm3 when liquid to 14.184 g/cm3 when solid. The coefficient of volume expansion is 181.59 × 10−6 at 0 °C, 181.71 × 10−6 at 20 °C and 182.50 × 10−6 at 100 °C. Solid mercury can be cut with a knife. A complete explanation of mercury's extreme volatility delves deep into the realm of quantum physics, but it can be summarized as follows: mercury has a unique electron configuration where electrons fill up all the available 1s, 2s, 2p, 3s, 3p, 3d, 4s, 4p, 4d, 4f, 5s, 5p, 5d, 6s subshells.
Because this configuration resists removal of an electron, mercury behaves to noble gases, which form weak bonds and hence melt at low temperatures. The stability of the 6s shell is due to the presence of a filled 4f shell. An f shell poorly screens the nuclear charge that increases the attractive Coulomb interaction of the 6s shell and the nucleus; the absence of a filled inner f shell is the reason for the somewhat higher melting temperature of cadmium and zinc, although both these metals still melt and, in addition, have unusually low boiling points. Mercury does not react with most acids, such as dilute sulfuric acid, although oxidizing acids such as concentrated sulfuric acid and nitric acid or aqua regia dissolve it to give sulfate and chloride. Like silver, mercury reacts with atmospheric hydrogen sulfide. Mercury reacts with solid sulfur flakes. Mercury dissolves many metals such as silver to form amalgams. Iron is an exception, iron flasks have traditionally been used to trade mercury.
Several other first row transition metals with the exception of manganese and zinc are resistant in forming amalgams. Other elements that do not form amalgams with mercury include platinum. Sodium amalgam is a common reducing agent in organic synthesis, is used in high-pressure sodium lamps. Mercury combines with aluminium to form a mercury-aluminium amalgam when the two pure metals come into contact. Since the amalgam destroys the aluminium oxide layer which protects metallic aluminium from oxidizing in-depth small amounts of mercury can corrode aluminium. For this reason, mercury is not allowed aboard an aircraft under most circumstances because of the risk of it forming an amalgam with exposed aluminium parts in the aircraft. Mercury embrittlement is the most common type of liquid metal embrittlement. There are seven stable isotopes of mercury, with 202Hg being the most abundant; the longest-lived radioisotopes are 194Hg with a half-life of 444 years, 203Hg with a half-life of 46.612 days. Most of the remaining radioisotopes have half-lives.
199Hg and 201Hg are the most studied NMR-active nuclei, having spins of 1⁄2 and 3⁄2 respectively. Hg is the modern chemical symbol for mercury, it comes from hydrargyrum, a Latinized form of the Greek word ὑδράργυρος, a compound word meaning "water-silver" – since it is liquid like water and shiny like silver. The element was named after the Roman god Mercury, known for his mobility, it is associated with the planet Mercury. Mercury is the only metal for which the al
Tantalum is a chemical element with symbol Ta and atomic number 73. Known as tantalium, its name comes from Tantalus, a villain from Greek mythology. Tantalum is a rare, blue-gray, lustrous transition metal, corrosion-resistant, it is part of the refractory metals group, which are used as minor components in alloys. The chemical inertness of tantalum makes it a valuable substance for laboratory equipment and a substitute for platinum, its main use today is in tantalum capacitors in electronic equipment such as mobile phones, DVD players, video game systems and computers. Tantalum, always together with the chemically similar niobium, occurs in the mineral groups tantalite and coltan. Tantalum is considered a technology-critical element. Tantalum was discovered in Sweden in 1802 by Anders Ekeberg, in two mineral samples – one from Sweden and the other from Finland. One year earlier, Charles Hatchett had discovered columbium, in 1809 the English chemist William Hyde Wollaston compared its oxide, columbite with a density of 5.918 g/cm3, to that of tantalum, tantalite with a density of 7.935 g/cm3.
He concluded that the two oxides, despite their difference in measured density, were identical and kept the name tantalum. After Friedrich Wöhler confirmed these results, it was thought that columbium and tantalum were the same element; this conclusion was disputed in 1846 by the German chemist Heinrich Rose, who argued that there were two additional elements in the tantalite sample, he named them after the children of Tantalus: niobium, pelopium. The supposed element "pelopium" was identified as a mixture of tantalum and niobium, it was found that the niobium was identical to the columbium discovered in 1801 by Hatchett; the differences between tantalum and niobium were demonstrated unequivocally in 1864 by Christian Wilhelm Blomstrand, Henri Etienne Sainte-Claire Deville, as well as by Louis J. Troost, who determined the empirical formulas of some of their compounds in 1865. Further confirmation came from the Swiss chemist Jean Charles Galissard de Marignac, in 1866, who proved that there were only two elements.
These discoveries did not stop scientists from publishing articles about the so-called ilmenium until 1871. De Marignac was the first to produce the metallic form of tantalum in 1864, when he reduced tantalum chloride by heating it in an atmosphere of hydrogen. Early investigators had only been able to produce impure tantalum, the first pure ductile metal was produced by Werner von Bolton in Charlottenburg in 1903. Wires made with metallic tantalum were used for light bulb filaments until tungsten replaced it in widespread use; the name tantalum was derived from the name of the mythological Tantalus, the father of Niobe in Greek mythology. In the story, he had been punished after death by being condemned to stand knee-deep in water with perfect fruit growing above his head, both of which eternally tantalized him. Anders Ekeberg wrote "This metal I call tantalum... in allusion to its incapacity, when immersed in acid, to absorb any and be saturated."For decades, the commercial technology for separating tantalum from niobium involved the fractional crystallization of potassium heptafluorotantalate away from potassium oxypentafluoroniobate monohydrate, a process, discovered by Jean Charles Galissard de Marignac in 1866.
This method has been supplanted by solvent extraction from fluoride-containing solutions of tantalum. Tantalum is dark, ductile hard fabricated, conductive of heat and electricity; the metal is renowned for its resistance to corrosion by acids. It can be dissolved with hydrofluoric acid or acidic solutions containing the fluoride ion and sulfur trioxide, as well as with a solution of potassium hydroxide. Tantalum's high melting point of 3017 °C is exceeded among the elements only by tungsten and osmium for metals, carbon. Tantalum exists in two crystalline phases and beta; the alpha phase is ductile and soft. The beta phase is brittle; the beta phase is metastable and converts to the alpha phase upon heating to 750–775 °C. Bulk tantalum is entirely alpha phase, the beta phase exists as thin films obtained by magnetron sputtering, chemical vapor deposition or electrochemical deposition from an eutectic molten salt solution. Natural tantalum consists of two isotopes: 181Ta. 181Ta is a stable isotope.
180mTa is predicted to decay in three ways: isomeric transition to the ground state of 180Ta, beta decay to 180W, or electron capture to 180Hf. However, radioactivity of this nuclear isomer has never been observed, only a lower limit on its half-life of 2.0 × 1016 years has been set. The ground state of 180Ta has a half-life of only 8 hours. 180mTa is the only occurring nuclear isomer. It is the rarest isotope in the Universe, taking into account the elemental abu
Titanium is a chemical element with symbol Ti and atomic number 22. It is a lustrous transition metal with a silver color, low density, high strength. Titanium is resistant to corrosion in sea water, aqua regia, chlorine. Titanium was discovered in Cornwall, Great Britain, by William Gregor in 1791, was named by Martin Heinrich Klaproth after the Titans of Greek mythology; the element occurs within a number of mineral deposits, principally rutile and ilmenite, which are distributed in the Earth's crust and lithosphere, it is found in all living things, water bodies and soils. The metal is extracted from its principal mineral ores by the Hunter processes; the most common compound, titanium dioxide, is a popular photocatalyst and is used in the manufacture of white pigments. Other compounds include a component of smoke screens and catalysts. Titanium can be alloyed with iron, aluminium and molybdenum, among other elements, to produce strong, lightweight alloys for aerospace, industrial processes, agri-food, medical prostheses, orthopedic implants and endodontic instruments and files, dental implants, sporting goods, mobile phones, other applications.
The two most useful properties of the metal are corrosion resistance and strength-to-density ratio, the highest of any metallic element. In its unalloyed condition, titanium is less dense. There are two allotropic forms and five occurring isotopes of this element, 46Ti through 50Ti, with 48Ti being the most abundant. Although they have the same number of valence electrons and are in the same group in the periodic table and zirconium differ in many chemical and physical properties; as a metal, titanium is recognized for its high strength-to-weight ratio. It is a strong metal with low density, quite ductile and metallic-white in color; the high melting point makes it useful as a refractory metal. It is paramagnetic and has low electrical and thermal conductivity. Commercially pure grades of titanium have ultimate tensile strength of about 434 MPa, equal to that of common, low-grade steel alloys, but are less dense. Titanium is 60% denser than aluminium, but more than twice as strong as the most used 6061-T6 aluminium alloy.
Certain titanium alloys achieve tensile strengths of over 1,400 MPa. However, titanium loses strength when heated above 430 °C. Titanium is not as hard as some grades of heat-treated steel. Machining requires precautions, because the material can gall unless sharp tools and proper cooling methods are used. Like steel structures, those made from titanium have a fatigue limit that guarantees longevity in some applications; the metal is a dimorphic allotrope of an hexagonal α form that changes into a body-centered cubic β form at 882 °C. The specific heat of the α form increases as it is heated to this transition temperature but falls and remains constant for the β form regardless of temperature. Like aluminium and magnesium, titanium metal and its alloys oxidize upon exposure to air. Titanium reacts with oxygen at 1,200 °C in air, at 610 °C in pure oxygen, forming titanium dioxide, it is, slow to react with water and air at ambient temperatures because it forms a passive oxide coating that protects the bulk metal from further oxidation.
When it first forms, this protective layer continues to grow slowly. Atmospheric passivation gives titanium excellent resistance to corrosion equivalent to platinum. Titanium is capable of withstanding attack by dilute sulfuric and hydrochloric acids, chloride solutions, most organic acids. However, titanium is corroded by concentrated acids; as indicated by its negative redox potential, titanium is thermodynamically a reactive metal that burns in normal atmosphere at lower temperatures than the melting point. Melting is possible only in a vacuum. At 550 °C, it combines with chlorine, it reacts with the other halogens and absorbs hydrogen. Titanium is one of the few elements that burns in pure nitrogen gas, reacting at 800 °C to form titanium nitride, which causes embrittlement; because of its high reactivity with oxygen and some other gases, titanium filaments are applied in titanium sublimation pumps as scavengers for these gases. Such pumps inexpensively and reliably produce low pressures in ultra-high vacuum systems.
Titanium is the ninth-most abundant element in the seventh-most abundant metal. It is present as oxides in most igneous rocks, in sediments derived from them, in living things, natural bodies of water. Of the 801 types of igneous rocks analyzed by the United States Geological Survey, 784 contained titanium, its proportion in soils is 0.5 to 1.5%. Common titanium-containing minerals are anatase, ilmenite, perovskite and titanite. Akaogiite is an rare mineral consisting of titanium dioxide. Of these minerals, only rutile and ilmenite have economic importance, yet they are difficult to find in high concentrations. About 6.0 and 0.7 million tonnes of those minerals were mined in 2011, respectively. Signi
Osmium is a chemical element with symbol Os and atomic number 76. It is a hard, bluish-white transition metal in the platinum group, found as a trace element in alloys in platinum ores. Osmium is the densest occurring element, with an experimentally measured density of 22.59 g/cm3. Manufacturers use its alloys with platinum and other platinum-group metals to make fountain pen nib tipping, electrical contacts, in other applications that require extreme durability and hardness; the element's abundance in the Earth's crust is among the rarest. Osmium is the densest stable element. Calculations of density from the X-ray diffraction data may produce the most reliable data for these elements, giving a value of 22.587±0.009 g/cm3 for osmium denser than the 22.562±0.009 g/cm3 of iridium. Osmium is a hard but brittle metal that remains lustrous at high temperatures, it has a low compressibility. Correspondingly, its bulk modulus is high, reported between 395 and 462 GPa, which rivals that of diamond; the hardness of osmium is moderately high at 4 GPa.
Because of its hardness, low vapor pressure, high melting point, solid osmium is difficult to machine, form, or work. Osmium forms compounds with oxidation states ranging from −2 to +8; the most common oxidation states are +2, +3, +4, +8. The +8 oxidation state is notable for being the highest attained by any chemical element aside from iridium's +9 and is encountered only in xenon, ruthenium and iridium; the oxidation states −1 and −2 represented by the two reactive compounds Na2 and Na2 are used in the synthesis of osmium cluster compounds. The most common compound exhibiting the +8 oxidation state is osmium tetroxide; this toxic compound is formed. It is a volatile, water-soluble, pale yellow, crystalline solid with a strong smell. Osmium powder has the characteristic smell of osmium tetroxide. Osmium tetroxide forms. With ammonia, it forms the nitrido-osmates OsO3N−. Osmium tetroxide is a powerful oxidizing agent. By contrast, osmium dioxide is black, non-volatile, much less reactive and toxic.
Only two osmium compounds have major applications: osmium tetroxide for staining tissue in electron microscopy and for the oxidation of alkenes in organic synthesis, the non-volatile osmates for organic oxidation reactions. Osmium pentafluoride is known; the lower oxidation states are stabilized by the larger halogens, so that the trichloride, tribromide and diiodide are known. The oxidation state +1 is known only for osmium iodide, whereas several carbonyl complexes of osmium, such as triosmium dodecacarbonyl, represent oxidation state 0. In general, the lower oxidation states of osmium are stabilized by ligands that are good σ-donors and π-acceptors; the higher oxidation states are stabilized by strong σ- and π-donors, such as O2− and N3−. Despite its broad range of compounds in numerous oxidation states, osmium in bulk form at ordinary temperatures and pressures resists attack by all acids and alkalis, including aqua regia. Osmium has seven occurring isotopes, six of which are stable: 184Os, 187Os, 188Os, 189Os, 190Os, 192Os.
186Os undergoes alpha decay with such a long half-life ×1015 years 140000 times the age of the universe, that for practical purposes it can be considered stable. Alpha decay is predicted for all seven occurring isotopes, but it has been observed only for 186Os due to long half-lives, it is predicted that 184Os and 192Os can undergo double beta decay but this radioactivity has not been observed yet.187Os is the descendant of 187Re and is used extensively in dating terrestrial as well as meteoric rocks. It has been used to measure the intensity of continental weathering over geologic time and to fix minimum ages for stabilization of the mantle roots of continental cratons; this decay is a reason. However, the most notable application of osmium isotopes in geology has been in conjunction with the abundance of iridium, to characterise the layer of shocked quartz along the Cretaceous–Paleogene boundary that marks the extinction of the non-avian dinosaurs 65 million years ago. Osmium was discovered in 1803 by William Hyde Wollaston in London, England.
The discovery of osmium is intertwined with that of platinum and the other metals of the platinum group. Platinum reached Europe as platina, first encountered in the late 17th century in silver mines around the Chocó Department, in Colombia; the discovery that this metal was not an alloy, but a distinct new element, was published in 1748. Chemists who studied platinum dissolved it in aqua regia to create soluble salts, they always observed a small amount of a insoluble residue. Joseph Louis Proust thought. Victor Collet-Descotils, Antoine François, comte de Fourcroy, Louis Nicolas Vauquelin observed iridium in the black platinum residue in 1803, but did not obtain enough material for further experiments; the two French ch
Ruthenium is a chemical element with symbol Ru and atomic number 44. It is a rare transition metal belonging to the platinum group of the periodic table. Like the other metals of the platinum group, ruthenium is inert to most other chemicals. Russian-born scientist of Baltic-German ancestry Karl Ernst Claus discovered the element in 1844 at Kazan State University and named it after the Latin name of his homeland, Ruthenia. Ruthenium is found as a minor component of platinum ores. Most ruthenium produced is used in thick-film resistors. A minor application for ruthenium is as a chemistry catalyst. A new application of ruthenium is as the capping layer for extreme ultraviolet photomasks. Ruthenium is found in ores with the other platinum group metals in the Ural Mountains and in North and South America. Small but commercially important quantities are found in pentlandite extracted from Sudbury, Ontario and in pyroxenite deposits in South Africa. Ruthenium, a polyvalent hard white metal, is a member of the platinum group and is in group 8 of the periodic table: Whereas all other group 8 elements have 2 electrons in the outermost shell, in ruthenium, the outermost shell has only one electron.
This anomaly is observed in the neighboring metals niobium and rhodium. Ruthenium does not tarnish unless subject to high temperatures. Ruthenium dissolves in fused alkalis to give ruthenates, is not attacked by acids but is attacked by halogens at high temperatures. Indeed, ruthenium is most attacked by oxidizing agents. Small amounts of ruthenium can increase the hardness of palladium; the corrosion resistance of titanium is increased markedly by the addition of a small amount of ruthenium. The metal can be plated by thermal decomposition. A ruthenium-molybdenum alloy is known to be superconductive at temperatures below 10.6 K. Ruthenium is the last of the 4d transition metals that can assume the group oxidation state +8, then it is less stable there than the heavier congener osmium: this is the first group from the left of the table where the second and third-row transition metals display notable differences in chemical behavior. Like iron but unlike osmium, ruthenium can form aqueous cations in its lower oxidation states of +2 and +3.
Ruthenium is the first in a downward trend in the melting and boiling points and atomization enthalpy in the 4d transition metals after the maximum seen at molybdenum, because the 4d subshell is more than half full and the electrons are contributing less to metallic bonding. Unlike the lighter congener iron, ruthenium is paramagnetic at room temperature, as iron is above its Curie point; the reduction potentials in acidic aqueous solution for some common ruthenium ions are shown below: Naturally occurring ruthenium is composed of seven stable isotopes. Additionally, 34 radioactive isotopes have been discovered. Of these radioisotopes, the most stable are 106Ru with a half-life of 373.59 days, 103Ru with a half-life of 39.26 days and 97Ru with a half-life of 2.9 days. Fifteen other radioisotopes have been characterized with atomic weights ranging from 89.93 u to 114.928 u. Most of these have half-lives that are less than five minutes except 105Ru; the primary decay mode before the most abundant isotope, 102Ru, is electron capture and the primary mode after is beta emission.
The primary decay product before 102Ru is the primary decay product after is rhodium. As the 74th most abundant element in Earth's crust, ruthenium is rare, found in about 100 parts per trillion; this element is found in ores with the other platinum group metals in the Ural Mountains and in North and South America. Small but commercially important quantities are found in pentlandite extracted from Sudbury, Canada, in pyroxenite deposits in South Africa; the native form of ruthenium is a rare mineral. 12 tonnes of ruthenium are mined each year with world reserves estimated at 5,000 tonnes. The composition of the mined platinum group metal mixtures varies depending on the geochemical formation. For example, the PGMs mined in South Africa contain on average 11% ruthenium while the PGMs mined in the former USSR contain only 2%. Ruthenium and iridium are considered the minor platinum group metals. Ruthenium, like the other platinum group metals, is obtained commercially as a by-product from nickel, copper, platinum metals ore processing.
During electrorefining of copper and nickel, noble metals such as silver and the platinum group metals precipitate as anode mud, the feedstock for the extraction. The metals are converted to ionized solutes by any of several methods, depending on the composition of the feedstock. One representative method is fusion with sodium peroxide followed by dissolution in aqua regia, solution in a mixture of chlorine with hydrochloric acid. Osmium, ruthenium and iridium are insoluble in aqua regia and precipitate, leaving the other metals in solution. Rhodium is separated from the residue by treatment with molten sodium bisulfate; the insoluble residue, containing
Metallurgy is a domain of materials science and engineering that studies the physical and chemical behavior of metallic elements, their inter-metallic compounds, their mixtures, which are called alloys. A special type of alloy was invented in 1995, when Taiwanese scientists invented the world's first high-entropy alloys of metals that can withstand the highest temperatures and pressures for use in industrial and technological applications such as state of the art race cars, submarines, nuclear reactors, jet airplanes, nuclear weapons, long range hypersonic missiles and many other areas of technology. Metallurgy is used to separate metals from their ore. Metallurgy is the technology of metals: the way in which science is applied to the production of metals, the engineering of metal components for usage in products for consumers and manufacturers; the production of metals involves the processing of ores to extract the metal they contain, 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, for technical advancement. The science of metallurgy is subdivided into physical metallurgy. Metallurgy is subdivided into ferrous metallurgy and non-ferrous metallurgy. Ferrous metallurgy involves processes and alloys based on iron while non-ferrous metallurgy involves processes and alloys based on other metals; 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, "work"; the word was an alchemist's term for the extraction of metals from minerals, the ending -urgy signifying a process manufacturing: it was discussed in this sense in the 1797 Encyclopædia Britannica. In the late 19th century it was extended to the more general scientific study of metals and related processes. In English, the pronunciation is the more common one in the Commonwealth.
The pronunciation is the more common one in the USA, is the first-listed variant in various American dictionaries. The earliest recorded metal employed by humans appears to be gold, which can be found free or "native". Small amounts of natural gold have been found in Spanish caves used during the late Paleolithic period, c. 40,000 BC. Silver, copper and meteoric iron can be found in native form, allowing a limited amount of metalworking in early cultures. Egyptian weapons made from meteoric iron in about 3000 BC were prized as "daggers from heaven". Certain metals, notably tin and copper, can be recovered from their ores by heating the rocks in a fire or blast furnace, a process known as smelting; the first evidence of this extractive metallurgy, dating from the 5th and 6th millennia BC, has been found at archaeological sites in Majdanpek and Plocnik, in present-day Serbia. To date, the earliest evidence of copper smelting is found at the Belovode site near Plocnik; this site produced a copper axe from 5500 BC.
The earliest use of lead is documented from the late neolithic settlement of Yarim Tepe in Iraq, "The earliest lead finds in the ancient Near East are a 6th millennium BC bangle from Yarim Tepe in northern Iraq and a later conical lead piece from Halaf period Arpachiyah, near Mosul. As native lead is rare, such artifacts raise the possibility that lead smelting may have begun before copper smelting." Copper smelting is documented at this site at about the same time period, although the use of lead seems to precede copper smelting. Early metallurgy is documented at the nearby site of Tell Maghzaliyah, which seems to be dated earlier, lacks pottery. Other signs of early metals are found from the third millennium BC in places like Palmela, Los Millares, Stonehenge. However, the ultimate beginnings cannot be ascertained and new discoveries are both continuous and ongoing. In the Near East, about 3500 BC, it was discovered that by combining copper and tin, a superior metal could be made, an alloy called bronze.
This represented a major technological shift known as the Bronze Age. The extraction of iron from its ore into a workable 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 wide variety of past cultures and civilizations; this includes the ancient and medieval kingdoms and empires of the Middle East and Near East, ancient Iran, ancient Egypt, ancient Nubia, Anatolia, Ancient Nok, the Greeks and Romans of ancient Europe, medieval Europe and medieval China and medieval India and medieval Japan, amongst others. Many applications and devices associated or involved in metallurgy were established in ancient China, such as the innovation of the blast furnace, cast iron, hydraulic-powered trip hammers, double acting piston bellows. A 16th century book by Georg Agricola called De re metallica describes the developed and complex processes of mining metal ores, metal extraction and metallurgy of the time.
Agricola has been described as the "father of metallurgy". Extractive metallurgy is the practice of removing valuable metals from an ore and refining the extracted