Borax Boron nitride

The main source of boron is a complex compound of boron called borax. About half of the world supply of borax comes from a large deposit in California s Mojave Desert. Borax is used as a cleaning agent and as fireproof insulation. Another compound of boron, boric acid, is used as a disinfectant and as an eye wash. A form of boron nitride is the second hardest known material only diamond is harder. These materials are classified as superabrasives. They are used in grinding wheels, which shape manufactured parts and tools. 

Boron nitride, BN, is a robust (sublimation point = 2603 K), chemically rather inert compound which is used as a ceramic material (e.g. in crucible manufacture). Preparative routes include the high-temperature reactions of borax with [NH4]C1, B2O3 with NH3, and B(OH)3 with [NHJCl. 

Less frequently used materials ceramics, for example, BN (boron nitride), aramid, or carbon fibers miscellaneous, for example, calcium fluoride, cerium fluoride, tungsten disulfide (WS2), mica, borax, silver sulfate, cadmium iodide, lead iodide, and talc. 

More than one boride phase can be formed with most metals, and in many cases a continuous series of solid solutions may be formed. Several methods have been used for the relatively large-scale preparation of metal borides. One that is commonly used is carbon reduction of boric oxide and the appropriate metal oxide at temperatures up to 2000 °C. Fused salt electrolysis of borax or boric oxide and a metal oxide at 700 1000 °C have also been used. Small-scale methods available include direct reaction of the elements at temperatures above 1000 °C and the reaction of elemental boron with metal oxides at temperatures approaching 2000 °C. One commercial use of borides is in titanium boride-aluminum nitride crucibles or boats for evaporation of aluminum by resistance heating in the aluminizing process, and for rare earth hexaborides as electronic cathodes. Borides have also been used in sliding electrical contacts and as cathodes in HaU cells for aluminum processing. 

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