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 percent-age is manufactured by the conventional method –carburization of tungsten powder- and covers the widest range of powder qualities in regard to average grain size (0.15 – 12 pm). All other methods in use yield in very fine or very coarse powder grades.
The conventional process of carburization comprises mixing of the respective tungsten powder of desired grain size with high purity carbon (lamp black or graphite) and reacting at temperatures between 1300 t0 1600 0C in hydrogen atmosphere, The average grain 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 speciffed but also a series of physical properties as there are: Average particle size, particle size distribution, apparent (bulk) density and homogeneity. High temperature carburized WC powders (1700 -2200 0C) are usually coarse 10 – 50 µm, but sometimes also 5 to 10 µm grades are treated that way, The percentage of high temperature WC is small.
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