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Niobium
Niobium is a chemical element with chemical symbol Nb (formerly columbium, Cb) and atomic number 41. It is a light grey, crystalline, and ductile transition metal. Pure niobium has a Mohs hardness rating similar to pure titanium, and it has similar ductility to iron. Niobium oxidizes in Earth's atmosphere very slowly, hence its application in jewelry as a hypoallergenic alternative to nickel. Niobium is often found in the minerals pyrochlore and columbite, hence the former name "columbium". Its name comes from Greek mythology: Niobe, daughter of Tantalus, the namesake of tantalum. The name reflects the great similarity between the two elements in their physical and chemical properties, which makes them difficult to distinguish. English chemist Charles Hatchett reported a new element similar to tantalum in 1801 and named it columbium. In 1809, English chemist William Hyde Wollaston wrongly concluded that tantalum and columbium were identical. German chemist Heinrich Rose dete ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tantalum
Tantalum is a chemical element with the symbol Ta and atomic number 73. Previously known as ''tantalium'', it is named after Tantalus, a villain in Greek mythology. Tantalum is a very hard, ductile, lustrous, blue-gray transition metal that is highly corrosion-resistant. It is part of the refractory metals group, which are widely used as components of strong high-melting-point alloys. It is a group 5 element, along with vanadium and niobium, and it always occurs in geologic sources together with the chemically similar niobium, mainly in the mineral groups tantalite, columbite and coltan. The chemical inertness and very high melting point of tantalum make it valuable for laboratory and industrial equipment such as reaction vessels and vacuum furnaces. It is used in tantalum capacitors for electronic equipment such as computers. Tantalum is considered a technology-critical element by the European Commission. History Tantalum was discovered in Sweden in 1802 by Anders ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Superconductivity
Superconductivity is a set of physical properties observed in certain materials where electrical resistance vanishes and magnetic flux fields are expelled from the material. Any material exhibiting these properties is a superconductor. Unlike an ordinary metallic conductor, whose resistance decreases gradually as its temperature is lowered even down to near absolute zero, a superconductor has a characteristic critical temperature below which the resistance drops abruptly to zero. An electric current through a loop of superconducting wire can persist indefinitely with no power source. The superconductivity phenomenon was discovered in 1911 by Dutch physicist Heike Kamerlingh Onnes. Like ferromagnetism and atomic spectral lines, superconductivity is a phenomenon which can only be explained by quantum mechanics. It is characterized by the Meissner effect, the complete ejection of magnetic field lines from the interior of the superconductor during its transitions into t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Superconducting Magnet
A superconducting magnet is an electromagnet made from coils of superconducting wire. They must be cooled to cryogenic temperatures during operation. In its superconducting state the wire has no electrical resistance and therefore can conduct much larger electric currents than ordinary wire, creating intense magnetic fields. Superconducting magnets can produce stronger magnetic fields than all but the strongest non-superconducting electromagnets, and large superconducting magnets can be cheaper to operate because no energy is dissipated as heat in the windings. They are used in MRI instruments in hospitals, and in scientific equipment such as NMR spectrometers, mass spectrometers, fusion reactors and particle accelerators. They are also used for levitation, guidance and propulsion in a magnetic levitation (maglev) railway system being constructed in Japan. Construction Cooling During operation, the magnet windings must be cooled below their critical temperature, the temperatur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ferroniobium
Ferroniobium is an important iron-niobium alloy, with a niobium content of 60-70%. It is the main source for niobium alloying of HSLA steel and covers more than 80% of the worldwide niobium production. The niobium is mined from pyrochlore deposits and is subsequently transformed into the niobium pentoxide Nb2O5. This oxide is mixed with iron oxide and aluminium and is reduced in an aluminothermic reaction to niobium and iron. The component metals can be purified in an electron beam furnace or the alloy can be used as it is. For alloying with steel the ferroniobium is added to molten steel before casting. The largest producers of ferroniobium are the same as for niobium and are located in Brazil and Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by to .... External links * *ISO 545 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heinrich Rose
Heinrich Rose (6 August 1795 – 27 January 1864) was a German mineralogist and analytical chemist. He was the brother of the mineralogist Gustav Rose and a son of Valentin Rose. Rose's early works on phosphorescence were noted in the Quarterly Journal of Science in 1821, and on the strength of these works, he was elected privatdozent at the University of Berlin from 1822, then Professor from 1832. In 1846 Rose rediscovered the chemical element niobium, proving conclusively that it was different from tantalum. This confirmed that Charles Hatchett had discovered niobium in 1801 in columbite ore. Hatchett had named the new element "columbium", from the ore in which niobium and tantalum coexist. The element was eventually assigned the name niobium by the IUPAC in 1950 after Niobe, the daughter of Tantalus in Greek mythology. In 1845 Rose published the discovery of a new element pelopium, which he had found in the mineral tantalite. After subsequent research pelopium w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Charles Hatchett
Charles Hatchett FRS FRSE (2 January 1765 – 10 March 1847) was an English mineralogist and analytical chemist who discovered the element niobium, for which he proposed the name "columbium". Hatchett was elected a Fellow of the Linnaean Society in 1795, and of the Royal Society in 1797. Hatchett was elected to the Literary Club in London in 1809 and became its treasurer in 1829. Life Charles Hatchett was born in Long Acre, London to John Hatchett (1729–1806), and Elizabeth Hatchett. John Hatchett was "(one of) the coachbuilders of London of the greatest celebrity". He later became a magistrate in Hammersmith. Charles Hatchett attended a private school, Fountayne's, in Marylebone Park, and was a self-taught mineralogist and analytical chemist. On 24 March 1786, Charles Hatchett married Elizabeth Martha Collick (1756–1837) at St Martin-in-the-Fields. Their children included: #John Charles Hatchett (bapt 27 January 1788 St Martin-in-the-Fields) #His daughter, Anna Frede ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Type-II Superconductor
In superconductivity, a type-II superconductor is a superconductor that exhibits an intermediate phase of mixed ordinary and superconducting properties at intermediate temperature and fields above the superconducting phases. It also features the formation of magnetic field vortices with an applied external magnetic field. This occurs above a certain critical field strength ''Hc1''. The vortex density increases with increasing field strength. At a higher critical field ''Hc2'', superconductivity is destroyed. Type-II superconductors do not exhibit a complete Meissner effect. History In 1935, Rjabinin and Shubnikov experimentally discovered the Type-II superconductors. In 1950, the theory of the two types of superconductors was further developed by Lev Landau and Vitaly Ginzburg in their paper on Ginzburg–Landau theory. In their argument, a type-I superconductor had positive free energy of the superconductor-normal metal boundary. Ginzburg and Landau pointed out the poss ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Columbite
Columbite, also called niobite, niobite-tantalite and columbate [], is a black mineral group that is an ore of niobium. It has a submetallic Lustre (mineralogy), luster and a high density and is a niobate of iron and manganese. This mineral group was first found in Haddam, Connecticut, in the United States. It forms a series with the tantalum-dominant analogue ferrotantalite and one with the manganese-dominant analogue manganocolumbite. The iron-rich member of the columbite group is ferrocolumbite. Some tin and tungsten may be present in the mineral. Yttrocolumbite is the yttrium-rich columbite with the formula . It is a radioactive mineral found in Mozambique. Columbite has the same composition and crystal symmetry ( orthorhombic) as tantalite. In fact, the two are often grouped together as a semi-singular mineral series called columbite-tantalite or coltan in many mineral guides. However, tantalite has a much greater specific gravity than columbite, more than 8.0 compared to co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Symbol
Chemical symbols are the abbreviations used in chemistry for chemical elements, functional groups and chemical compounds. Element symbols for chemical elements normally consist of one or two letters from the Latin alphabet and are written with the first letter capitalised. History Earlier symbols for chemical elements stem from classical Latin and Greek vocabulary. For some elements, this is because the material was known in ancient times, while for others, the name is a more recent invention. For example, Pb is the symbol for lead (''plumbum'' in Latin); Hg is the symbol for mercury (''hydrargyrum'' in Greek); and He is the symbol for helium (a new Latin name) because helium was not known in ancient Roman times. Some symbols come from other sources, like W for tungsten (''Wolfram'' in German) which was not known in Roman times. A three-letter temporary symbol may be assigned to a newly synthesized (or not yet synthesized) element. For example, "Uno" was the temporary sy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyrochlore
Pyrochlore () is a mineral group of the niobium end member of the pyrochlore supergroup. The general formula, (where A and B are metals), represent a family of phases isostructural to the mineral pyrochlore. Pyrochlores are an important class of materials in diverse technological applications such as luminescence, ionic conductivity, nuclear waste immobilization, high temperature thermal barrier coatings, automobile exhaust gas control, catalysts, solid oxide fuel cell, ionic/electrical conductors etc. Occurrence The mineral is associated with the metasomatic end stages of magmatic intrusions. Pyrochlore crystals are usually well formed (euhedral), occurring usually as octahedra of a yellowish or brownish color and resinous luster. It is commonly metamict due to radiation damage from included radioactive elements. Pyrochlore occurs in pegmatites associated with nepheline syenites and other alkalic rocks. It is also found in granite pegmatites and greisens. It is characteris ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Superalloy
A superalloy, or high-performance alloy, is an alloy with the ability to operate at a high fraction of its melting point. Several key characteristics of a superalloy are excellent mechanical strength, resistance to thermal creep deformation, good surface stability, and resistance to corrosion or oxidation. The crystal structure is typically face-centered cubic (FCC) austenitic. Examples of such alloys are Hastelloy, Inconel, Waspaloy, Rene alloys, Incoloy, MP98T, TMS alloys, and CMSX single crystal alloys. Superalloy development has relied heavily on both chemical and process innovations. Superalloys develop high temperature strength through solid solution strengthening and precipitation strengthening from secondary phase precipitates such as gamma prime and carbides. Oxidation or corrosion resistance is provided by elements such as aluminium and chromium. Superalloys are often cast as a single crystal—while grain boundaries may provide strength at low temperatu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbide
In chemistry, a carbide usually describes a compound composed of carbon and a metal. In metallurgy, carbiding or carburizing is the process for producing carbide coatings on a metal piece. Interstitial / Metallic carbides The carbides of the group 4, 5 and 6 transition metals (with the exception of chromium) are often described as interstitial compounds. These carbides have metallic properties and are refractory. Some exhibit a range of stoichiometries, being a non-stoichiometric mixture of various carbides arising due to crystal defects. Some of them, including titanium carbide and tungsten carbide, are important industrially and are used to coat metals in cutting tools. The long-held view is that the carbon atoms fit into octahedral interstices in a close-packed metal lattice when the metal atom radius is greater than approximately 135 pm: *When the metal atoms are cubic close-packed, (ccp), then filling all of the octahedral interstices with carbon achieves 1:1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
