84% yellow tungsten oxide may be used to produce high quality ultrafine tungsten carbide (WC) powder by carbonization method. The producing processes are shown as follows:
1. Mix yellow tungsten oxide (mass fraction of 84%) and carbon (mass fraction of 16%) by mixer, and granulate to particle (grain size of 3mm) by granulator, then dry and mixed material is obtained.
2. Move material to the rotary furnace for continuous reduction/carbonization, the original material changes during the reaction:
WO3→WO2.9→WO2.72→WO2.0→W→W2C→WC
WO3 was heated in the first furnace under 1247°C with N2 atmosphere and the mixture of WO2.72, WO2 and W is obtained. Ultrafine crystalline appears in the transition process from WO2.72 to WO2.
Tungsten powder is carbonized in the second furnace under 1500°C with H2 atmosphere, while small amount of growth inhibitor is added to prevent enlarging of ultrafine tungsten carbide crystalline.
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