cBN-WC-12Co硬质合金的SPS制备及强化机理研究左冬华,林晨光,谢兴铖,曹瑞军,林中坤

Research on Preparation and Strengthening Mechanism of cBN-WC-12Co Cemented Carbides by SPS

摘要:

采用放电等离子体烧结（SPS）技术制备出cBN-WC-12Co硬质合金，分析了cBN的热稳定性，研究了cBN添加量和烧结温度对合金硬度和致密度的影响，并讨论了cBN强化机理。结果表明：cBN的热稳定性温度为1355℃，cBN-WC-12Co合金的烧结致密化最低温度在1150℃左右，当烧结温度为1250℃，cBN保持了较好的热稳定性，不发生相变；在相同烧结温度下，cBN-WC-12Co合金致密性均要好于WC-12Co合金；1150℃时合金C15的致密度和硬度（HV10）均达到最大值，分别为99.7%和1997；当cBN含量低于15vol%时，在一定程度上，cBN含量的增加有利于抑制合金中WC晶粒长大，并通过WC晶粒的毛细吸附促进合金致密化；合金中的cBN可以阻止裂纹等缺陷进一步扩展，有利于改善合金力学性能。

Abstract:

cBN-WC-12Co cemented carbides were prepared by spark plasma sintering (SPS) technique in this paper. The thermal stability of cBN was analyzed. The effect of cBN content and sintering temperature on the hardness and density of the cemented carbides were discussed, and the strengthening mechanism of cBN was discussed. The results show that the thermal stability temperature of cBN is 1335℃. The lowest dense sintering temperature of cBN-WC-12Co cemented carbides is about 1150℃, and cBN keeps an ideal thermal stability with no phase transition at 1250℃. The density of cBN-WC-12Co cemented carbides is better than WC-12Co at the same sintering temperature; The alloy C15 sintered at 1150℃ is with the highest density and hardness (HV10), which are 99.7% and1997,respectively; The increase of cBN content is beneficial to inhibit the growth of WC grains, to a certain degree, when the content of cBN is lower than 15vol%. The smaller WC grain is helpful to promote the densification of the cemented carbides through its capillary adsorption ,while the cBN can prevent the spread of crack and other defects, then to improve the mechanical properties of the cemented carbides.