Submicron boron carbide powder

Carbides of metals and other elements have been produced by this approach, including carbides of boron, silicon, titanium, zirconium, hafnium, vanadium, niobium, molybdenum, tungsten, tantalnm, and thorium (Funke, Klementiev, Kosukhin, 1969 Sheppard Wilson, 1972 MacKinnon Wickens, 1973 Chase, 1974 Steiger Wilson, 1974 Swaney, 1974 MacKinnon Renben, 1975). The produced caibide particles are very small their diameter is usually about 20-200 mu. Halides are mixed with hydrocarbons, usually in a ratio H2 Me = 2-30. The gas mixture is heated up in plasma to temperatures of 1300-4000 K time of synthesis exceeds 50 ms. As an example, production of submicron boron carbide powder from gaseous boron trichloride and methane occurs in the strongly endothermic process ... 

The only technically important sintering additive for boron carbide is carbon, as discovered almost simultaneously by Schwetz and Vogt [189], Henney and Jones [190], and Suzuki et al. [191], which today allows the routine production of dense parts. An amount ranging from 1 to 6 mass-% is sufficient to obtain almost theoretical density. Schwetz and Grellner [192] added phenolic resin (corresponding to 1-3 mass-% C) to a submicron B4C powder and obtained >98% density at 2150°C. The resins are pyrolized at temperatures up to 1000°C and they leave a... 

Different processing routes have been applied to synthesize this class of composite material. Besides the classical method of powder mixing using submicron SiC, B4C and carbon or carbon-containing precursors, followed by forming and subsequent heat treatment ]313], the infiltration of boron carbide preforms with organic precursors such as PCS, followed by heat treatment [400, 401] or the pressure-assisted reaction sintering of silicon borides with elemental carbon [423], have been used. 

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