Refining mechanisms of arsenic during preparation process of ultrafine WC powder by nitridation-carbonization method
To simplify the preparation process and prepare ultrafine WC powder,a certain amount of As element was added to the ammonium paratungstate precursor.The mechanism of As in the preparation process of ultrafine WC powder by nitridation-carbonization method was systematically discussed.The results show that when the carbonization temperature was 1400 ℃,the nitridation temperature increased from 500 to 600 ℃,and the As content increased from 0 to 0.3 wt.％,the average particle size of the prepared WC powder decreased from 2.23 to 0.22 μm,and the particle uniformity was significantly improved.The As element in the nitrided product was in the form of W2O3(AsO4)2,which was easily enriched or distributed between the two phases on the surface of the nitrided products(NH4)0.42 WO3 and WN,hindering the growth of WC grains during the carbonization process.Consequently,ultrafine WC powder was prepared.
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