Tungsten carbide powder is the intermediate in the line from W powder to cemented carbides. It can be produced from different raw materials and by different processes. By far the biggest percentage is manufactured by the conventional method - carburization of tungsten powder - and covers the widest range of powder qualities in regard to average particle size (0.15–12µm). All other methods in use yield very fine or very coarse powder grades.
The conventional process of carburisation comprises mixing of the respective tungsten powder of desired particle size with high purity carbon (lamp black or graphite) and reacting at temperatures between 1,300 to 1,600°C in hydrogen atmosphere. The average particle size and particle size distribution of the original tungsten powder determine size and distribution of the WC powder.
The final carbon content of the WC Powder depends on the production mode of the hardmetal producer and is one item of the rigid specification, and varies from slightly sub-stoichiometric to stoichiometric (6.13% C) to slightly over-stoichiometric. But not only is the carbon content specified but also a series of physical properties including: average particle size, particle size distribution, apparent (bulk) density and homogeneity.
High temperature carburised WC powders (1,700–2,200 °C) are usually coarse 10 to 50µm, but sometimes also 5 to 10µm grades are treated that way. The percentage of high temperature WC is small.
Tungsten carbide powder is packaged in sealed polyethylene-lined steel drums.