放电等离子烧结制备超细WC-Co硬质合金

Preparation of superfine WC-Co cemented carbides by spark plasma sintering process

采用放电等离子烧结(SPS)技术制备了超细WC-10Co硬质合金.研究了烧结温度及烧结气氛对WC-Co硬质合金组织及性能的影响.研究发现:烧结体密度随烧结温度的升高而增大,但由于钴的蒸发,合金的成分偏离了原粉末的成分,且随着烧结温度的升高及炉内气压的降低,钴的蒸发速率加大.因此,通过提高炉内气压,可以使合金的成分基本接近原粉末成分,降低了合金的成分偏离.结果表明:炉内气压升高到200 Pa,烧结压力为30 MPa时,在1250℃烧结WC-10.07Co粉末5 min,烧结体中钴的质量分数可以控制在10.02%,密度和硬度分别达到了14.62 g.cm-3和HRA 92.4.

Spark plasma sintering （SPS） process was used to prepare superfine WC-10Co cemented carbides. The effects of sintering temperature and sintering atmosphere on the microstructure and properties of WC-Co cemented carbides were investigated. The results show that the density of the compacts increases with increasing sintering temperature. However the composition of the compacts is different from that of the starting powders because of the evaporation of Co, and the evaporation rate of Co increases with the increase in sintering temperature and the decrease in atmosphere pressure. It is found that the composition of the compacts can be very close to that of the starting powders by increasing the atmosphere pressure. The mass fraction of Co in the compacts sintered at 1 250℃ for 5min under 30MPa in the argon atmosphere of 200Pa is 10.02%, and the density and hardness are 14.62g·cm^-3 and HRA 92.4, respectively.