Titanium carbide plasma synthesis

Although the synthesis of nanooxides particles is well known (sol-gel or hydrothermal processes), the synthesis of carbide or nitride nanoceramics with a plasma torch is much more complicated, the main challenges being the control of the process (hydrodynamic flows) and the control of the chemical composition of the end products after the plasma reaction. At the present time, some products such as titanium zinc and cesium nanooxides are already used for health-care applications (dry skin cream, UV-blocking cream, anti-wrinkle cream) or polishing slurries. 

This method was applied to produce carbides of titanium, zirconium, lead, and bismuth (Barcicki Myrdzik, 1974). Applications ofthe method are limited becanse of insufficient contact between solid particles in the presence of plasma flow if the solid mixtnre is not bricked or sintered. The efficiency of the process arranged in bricks or sintered solid mixture is limited by radiation heat losses and insufficient heat transfer inside of the brick, especially taking into account the decrease of density dne to CO formation (7-92). The most effective condensed-phase synthesis of carbides (7-92) is that from melt containing carbon compounds (Tumanov, 1981). A relevant example is the synthesis of carbides of uraninm and plutonium from a melt containing their nitrites and carbon compoimds (Coppinger Johnson, 1969). 

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 ... 

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