Niobium - by-element subgroup of the fifth group of the fifth period of the periodic table of chemical elements of Mendeleev, atomic number 41. Denoted Nb (Latin Niobium). Simple substance niobium - a brilliant silvery-gray color.
Niobium was discovered in 1801 by British scientist Charles Hatchet in the mineral (Colombia), found in the basin. Colombia, and therefore called "Columbia."
In 1844, the German chemist Heinrich Rose renamed it "niobium" in honor of the daughter of Tantalus Niobe than emphasized the similarities between the niobium and tantalum. However, in some countries (USA, UK) has long maintained the original name of the item - Columbia, and only in 1950, by the decision of the International Union of Pure and Applied Chemistry element was finally given the name niobium.
Clark niobium 18 g / t Niobium content increases from ultramafic (0.2 g / t Nb) to acid rocks (24 g / t Nb). Niobium tantalum always followed. Similar chemical properties of niobium and tantalum together cause it was sitting in the same minerals and participation in common geological processes. Niobium can replace titanium in some titaniferous minerals (sphene, allanite, perovskite, biotite). The form of niobium in nature may be different: scattered (in rock-forming and accessory minerals of igneous rocks) and mineral. In total, more than 100 known minerals containing niobium. Of these, industrial importance only some, sometimes used euxenite, Torola, ilmenorutil and minerals containing niobium as impurities (ilmenite, cassiterite, wolframite). In alkaline - ultramafic rocks scattered in niobium minerals perovskite and eudialyte. In the exogenous processes of niobium and tantalum minerals, being stable, can accumulate in dellyuvialno alluvial placers (placer columbite), sometimes in bauxite weathering crust.
Niobium deposits are located in the United States, Japan, Russia, Brazil, and Canada.
Niobium ore - usually complex and metal-poor. Ore concentrates containing Nb2O5: pirohlorovye - not less than 37%, loparite - 8%, columbite - 30-60%. Most of them are processed aluminum-or silikotermicheskim reinstatement ferronioby (40-60% Nb) and ferrotantalonioby. Niobium metal produced from ore concentrates on complex technology in three stages:
autopsy concentrateseparation of niobium and tantalum, and getting their pure chemical compounds,recovery and refining of niobium metal and its alloys.Major industrial production methods and Nb alloys - alumino-thermic, natriytermichesky, karbotermichesky: a mixture of Nb2O5 and soot initially obtained at 1800 ° C in an atmosphere vodorodakarbid, then a mixture of carbide and pentoxide at 1800-1900 ° C in a vacuum - metal, for niobium alloys this mixture is added to the oxides of the alloying metals alternatively niobium reduced at high temperature in a vacuum directly from Nb2O5 soot. Natriytermicheskim way niobium reduced sodium from K2NbF7, aluminothermic-aluminum of Nb2O5. Compact metal (alloy) produced by powder metallurgy, sintering of compacted powders rods in a vacuum at 2300 ° C or electron beam and vacuum arc melting, high-purity single crystals of niobium - float-electron-beam zone melting.
Niobium - shiny silver-gray metal with a body-centered cubic crystal lattice of α-Fe, a = 0.3292 nm.
The use and production of niobium increases rapidly due to a combination of its properties, such as refractoriness, low thermal neutron capture cross section, the ability to form a high-temperature, superconducting and other alloys, corrosion resistance, getter properties, low electron work function, good machinability and pressure in the cold weldability. Main applications of niobium: rocket science, aerospace engineering, radio engineering, electronics, chemical, EQUIPMENT, nuclear power.
Of pure niobium and its alloys are made of aircraft parts, casings for uranium and plutonium fuel rods, tubes and containers for liquid metals, parts of electrolytic capacitors, the "hot" electronic valves (for the radar) and a powerful generator tubes (anode, cathode, grid etc.), corrosion-resistant equipment for the chemical industry.Niobium-alloyed other nonferrous metals, including uranium.Niobium is used in cryotron - superconducting computer components. Niobium is also known that it is used in the accelerating structure of the Large Hadron Collider.Intermetallic alloys, niobium
Niobium alloys with titanium and zirconium are used to make superconducting solenoids.Niobium and tantalum alloys in many cases replace tantalum, which gives large economic effect (niobium cheaper and almost twice better than tantalum).Niobium is introduced (in the amount of 5 * (C%) and 0.6% niobium) in chrome-nickel stainless steel to prevent intergranular corrosion (including one that otherwise would have started after welding stainless steel) and fracture in steel etc . types to improve their properties.Niobium is used in the minting of collector coins. Thus, the Bank of Latvia states that collection coins in denominations of 1, along with the silver armor used niobium.The use of compounds of niobium
Niobium - a catalyst in the chemical industry;in the production of refractories, cermets, special glasses, nitride, carbide, niobates.Niobium carbide (mp. 3480 ° C) in the alloy carbide and zirconium carbide, uranium-235 is the major structural material for nuclear fuel rods of solid rocket motors.Niobium nitride is used for the production of thin and ultra-thin superconducting films with a critical temperature of 5 to 10 K with a narrow transition around 0.1 K.Superconducting materials of the first generation
One of the most actively used superconductors (superconducting transition temperature of 9.25 K). Niobium compounds are superconducting transition temperature to 23.2 C.Industrial temperature superconductorsNiobium is also used in magnetic alloys.It is used as an alloying additive.Niobium nitride is used for the production of superconducting bolometers.Exceptional resistance of niobium and tantalum alloys in superheated steam of cesium-133 makes it one of the most preferred and cheap construction materials for thermionic large generators.