Effect Of Inhibitors On Properties Of Ultra-fine WC-Co Cemented Carbides

In this paper, the effects of grain growth inhibitors on the sintering character, properties and microstructure of ultra-fine cemented carbides were studied.The properties of ultra-fine cemented carbides were tested, for example, contraction percentage, density, hardness, TRS, coercive force and so on. During the experiments, it was shown that the longer the ball milling time was, the grain size of inhibitors was smaller, and the effect of inhibitors was better. The influence of suppressing process on the contraction percentage of ultra-fine cemented carbides was obvious. The density of ultra-fine cemented carbides was achieved a fully dense state nearly after the vacuum pre-sintering and HIP. vacuum sintering with Ar process is very helpful to enhance properties of ultra-fine cemented carbides. There should be no pore in the ultra-fine cemented carbides and the properties of ultra-fine cemented carbides were very superior after vacuum and pressure sintering in the factory. It was found that the oxygen absorbed in the inhibitors and other powder during the high energy ball milling leaded to product decarbonizion in the ultra-fine cemented carbides. It made the TRS of ultra-fine cemented carbides reducing. Adding the content of carbide would remove the total decarbonizion, and the ultra-fine cemented carbides with fine microstructure and well properties would be got.Results have been shown that when different kinds of inhibitors were added at the same time in proper content, the grain size of WC was refined. They were helpful to enhance the properties of ultra-fine cemented carbides. When 0.3%VC/0.3%Cr3C2/0.4% TaC were added, the hardness of YG8 reached 93.8HRA, the TRS was 2290Mpa and the hardness of YG10 reached 93.3HRA, the TRS was 2250Mpa.