Study on Ball Milling and Forming Processes of Ultrafine WC-Co Cemented Carbide Containing Composite Carbides
Ultrafine WC-Co composite powders were prepared by high-energy ball milling method,the effects of ball milling methods(individual pre-milling method,wet milling and open-jar method),ball mil-ling time,and forming processes(ordinary molding,cold isostatic pressing)on the microstructure and me-chanical properties of ultrafine WC-Co cemented carbide containing composite carbides were investigated.The results show that compared with the individual pre-milling method,the ultrafine cemented carbide ob-tained by the wet milling and open-jar method has uniform microstructure and fine grains,which meets the requirements of ultrafine cemented carbide,the distribution of complosite carbides is basically uniform,and the comprehensive physical and mechanical properties of the cemented carbide are better.With the prolon-gation of ball milling time using the wet milling and open-jar method,WC powder is constantly crushed and refined,the obtained cemented carbide has gradually reduced WC grain size and slightly increased hardness and coercive force,but its densification,relative magnetic saturation strength and transverse rupture strength decrease.Comprehensively for the wet milling and open-jar method,a suitable pre-milling time for composite carbides is 12 h.Compared with ordinary molding,the ultrafine WC-Co cemented carbide with composite carbides prepared by cold isostatic pressing has a lower linear shrinkage and slightly improved hardness,density and transverse rupture strength.
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