烧结方法对WC-Co硬质合金性能的影响

Effect of sintering technologies on properties of WC-Co cemented carbides

以原位还原碳化反应法制备的超细WC-Co复合粉为原料,分别采用放电等离子烧结、低压烧结和真空烧结工艺获得块体硬质合金,系统研究烧结方法对合金的显微组织、密度及力学性能的影响。结果表明:放电等离子烧结的合金中,主相为WC和Co,有少量η相(Co6W6C),低压烧结和真空烧结获得的合金中物相为WC和Co;所用3种不同的烧结方法均能获得细晶块体硬质合金,其中放电等离子烧结的晶粒最细为0.35μm;低压烧结合金具有优异的综合性能,HV30为15 121 MPa,断裂韧性为13.6 MPa.m1/2,横向断裂强度为4 210 MPa。

Spark plasma sintering （SPS）, sinter-hot isostatic pressing （sinter-HIP） and vacuum sintering （VS） were carried out for densification of ultrafine WC-Co composite powder synthesized by in-situ reduction-carbonization reactions. The microstructures and properties of the WC-Co cemented carbides prepared by above different sintering processing were investigated and compared systematically. The effect of the sintering process on the phases and properties of the sintered alloys was investigated. The results show that the main phases of the cemented carbides are WC, Co and a little ~/ （Co6W6C） phase coexisting in the SPSed, while WC and Co phases in the alloys prepared by sinter-HIP and VS. The present study also shows that those sintering processes can be used for preparing cemented tungsten carbides with fine WC grains, and the SPSed alloy has the finest grain size of 0.35 pm, the sinter-HIPed one provides excellent properties with HV30 of 15 121 MPa, fracture toughness of 13.6 MPa.m1/2 and TRS of 4 210 MPa.