放电等离子烧结压力对超细WC-Co硬质合金性能的影响

通过分析放电等离子烧结致密化过程,确定了致密化温度;研究了SPS烧结过程中压力对WC-Co硬质合金致密化、显微组织及性能的影响。结果表明,放电等离子烧结粉末在1 130℃时,达到最大收缩率;烧结压力的增加,样品的致密度、硬度增加;断裂韧性的变化集中在11.5~12.1 MPa.m1/2之间,和硬度的变化呈现相反的趋势;烧结压力相对较小时,样品WC晶粒较粗大且不均匀;在40 MPa和55 MPa时,晶粒相对较小且分布均匀。要得到高性能、高致密度的样品,合理的烧结温度在1 200℃以上,烧结压力为40 MPa。

Effect of Pressures on Performance of Ultrafine WC-Co Cemented Carbide by Spark Plasma Sintering

By analyzing the spark plasma sintering process, the densification temperature of WC-Co cemented carbide was determined. The effect of sintering pressure on the densification, microstructure and properties of SPS WC-Co was investigated. The results indicates that the maximum shrinkage rate of sintering powder takes place at 1 130℃ by spark plasma sintering; the density and hardness of the samples increase with the increasing of the sintering pressure; the fracture toughness is concentrated in the range of 11.5 - 12.1 MP m1/2, which shows the opposite trend to hardness; when sintering pressure is relatively smaller, WC grain size of the samples is coarse and unevenly distributes; when sintering pressure is 40 MPa or 55 MPa, the grain is relatively small and evenly distributes. To get high performance, high density of the WC-Co sample, a reasonable sintering temperature is above 1 200 ℃, with sintering pressure is 40 MPa.