Making carbides of high-melting metals.

摘要

Fine-grained tungsten carbide is made direct from WO3 powder, i.e. without going through the elemental metal, which would be slow and would require high temperatures. The WO3 is reacted at 800C with carbon which is in a form sufficiently active to nucleate carbide in preference to the elemental metal, in this case carbon monoxide gas. The starting WO3 is of 1 mu m particles, and the reaction takes 2 hours, yielding WC particles of size 0.1 to 0.2 mu m.