Preparation and microstructure of layered structure functional gradient cemented carbides

Abstract

In this study, ultrafine WC powder was used as raw material, cubic carbonitrides Ti(C,N) and (W,Ti)C were added as gradient former, the cemented carbides with cubic carbide free layer (CCFL) structure was prepared by two-step sintering which was pre-sintering combined gradient sintering. The effect of gradient sintering temperature on the free-cubic layer structure formation and grain growth was studied. The results show that the layer structure gradient-cemented carbide with free-cubic phase in the surface can be prepared by two-step sintering when the ultrafine WC powder was used as raw material. However, many abnormal WC grains appeared after pre-sintering and gradient sintering. In the process of gradient sintering, with the increase of gradient sintering temperature, the thickness of free-cubic phase layer does not increase obviously, but the grain size of WC increases more, especially the number and size of abnormal WC grains growth increased.