Synthesis of tungsten monocarbide by self-propagating high-temperature synthesis in the presence of an activative additive

Tungsten monocarbide was synthesized by Self-Propagating High-Temperature S ynthesis. A SHS technique was developed in this work for W-C system charact erized by a low adiabatic combustion temperature of 1000 K. Samples were sy nthesized by in combustion wave propagating along compacts of elemental tun gsten, carbon and a highly exothermal mixture [Mg + (-C2F4-)n] as an activa tive additive under argon atomsphere of 1 atm. A quite high conversion rate was achieved at a combustion temperature of 2109 K. It is shown that in th e presence of a small amount of (about 10 wt.%) the additive mixture acquir es the capacity to burn and sustain the combustion front wave propagating. The lattic of tungsten monocarbide obtained was hexagonal and its particle size was 1 similar to 2 mum. In the final product, MgF2 and asmall amount o f W2C, both byproducts, were completely removed by acidic leaching. The pur ity of the tungsten monocarbide was 99% after leaching. (C) 2001 Kluwer Aca demic Publishers.