Preparation And Microstructures And Properties Of Ultra-fine WC-10Co Cemented Carbides

Ultra-fine WC-Co cemented carbides with the characteristic of high hardness and high strength are used widely in machining, integrated circuit, etc. In this article, Ultra-fine WC-10Co composite powder adding VC, TiC and Ce was used as the raw material. Ultra-fine cemented carbides were produced by the vacuum sintering process without pressure. The effect and mechanism of the additive composition and the sintering process about microstructure and properties of the Ultra-fine WC-10Co cemented carbides. sintering temperature, phase composition and Microstructure of the Ultra-fine WC-10Co cemented carbides were analysed by DTA, TG, SEM, EDS and XRD, etc. the density of cemented carbides was measured by Archimedes principle. The hardness and the bending strength of cemented carbides were measured by Vickers hardness tester and Multi-purpose electronic test machine.The particles size of VC and TiC decreased along with the ball mill time. The particles size was about 0.3μm when the ball-milling time was 48 hours. Extending ball-milling time, the particle size did not change greatly. The liquid phase and eutectic temperature of WC-10Co cemented carbides did not change after VC and TiC were added.The grain size of WC became smaller with the addition of VC increased. It was between 0.3μm and 0.5μm when the addition was 0.6wt%.The size was no longer smaller if the addition of VC continue to increase. In addition, there was the phenomenon of Co gathered. The size and distribution of WC grain became smaller and uniform when the right amount Ce was added. The relative density of cemented carbides was improved at the time. The reason is that the dissolution recrystallization process of the fine WC grains were restrained. The high the sintering temperature, the WC grain was thicker and the relative density was better, when the temperature was below 1450℃. When the sintering temperature is 1500℃, holes emerged that was because the loss of Co.The more VC content, the hardness of WC-10Co cemented carbides was higher and the bending strength was lower. The hardness of WC-10Co-0.6VC cemented carbides was improved when the Ce content became more. The bending strength increased at first, then decreased. It was the highest when the additive amount of Ce was 0.4wt%. The sintering temperature rose, the hardness of WC-10 Co-0.6VC cemented carbides was reduced, and the bending strength was improved at first, then reduced. the bending strength was the highest when the sintering temperature was 1400℃.