【作者】 雷贻文；

【导师】 吴恩熙；

【作者基本信息】 中南大学 ， 材料学， 2003， 硕士

【摘要】 本文系统研究了晶粒长大抑制剂的种类、添加方式、添加量对WC-12％Co超细硬质合金性能的影响。按正交试验方法，设计了添加VC／Cr₃C₂及（TaNb）C／Cr₃C₂晶粒长大抑制剂制备超细硬质合金的试验方案，研究其对WC-12％Co超细硬质合金合金烧结特性、微观结构及合金性能的影响。 试验结果表明，同时添加多种晶粒长大抑制剂可抑制合金中的WC晶粒长大，并且对合金综合性能的提高更为有利，即实现高抗弯强度，高硬度的“双高”性能，其中，晶粒抑制剂含量为0.5％Cr₃C₂+0.2％VC时，制备的WC-12％Co超细硬质合金的抗弯强度达3786MPa，硬度为91.7HRA，WC平均晶粒度为0.6微米；晶粒抑制剂含量为0.3％Cr₃C₂+0.4％（TaNb）C时，制备的WC-12％Co超细硬质合金的抗弯强度达3790 MPa，硬度为91.6 HRA，WC平均晶粒度为0.8微米。真空／压力烧结工艺对含抑制剂的超细硬质合金综合性能的提高非常有利，对钴含量较低的合金更为明显。合金的扫描电镜及金相显微镜分析表明，用这种工艺制得的超细硬质合金孔隙度低(A₀₂，无脱碳相或游离碳组织缺陷，且WC晶粒分布均匀，无WC晶粒异常长大现象。超细硬质合金烧结特性试验证实，超细合金开始收缩的烧结温度及最大收缩率时的烧结温度均低于普通细颗粒硬质合金；添加晶粒抑制剂将阻碍超细晶硬质合金固相烧结时的致密化动力学过程，但使液相开始出现的温度有所降低。 文章还讨论了晶粒长大抑制剂在超细硬质合金烧结过程中的作用机理，认为晶粒抑制剂吸附在WC颗粒表面，阻碍了液相烧结时WC颗粒的溶解—析出过程，从而使WC晶粒得到细化。更多还原

【Abstract】 In this paper, different content of mixed VC/Cr3C2 or (TaNb)C /Cr3C2 were added to WC-12%Co according to orthogonal experimental design. The effects of inhibitors on the sintering character, properties and microstructure of superfine cemented carbides are studied.Results show that when different kinds of inhibitors are added at the same time in proper content, the alloys’ WC grains are fined. They are helpful to enhance the properties of the alloys. When 0.5%Cr3C2/0.3% VC are added ,the bb of superfine grained hardmetal reaches 3786 MPa,the hardness is 91.7HRA and the alloys’ WC grains are under 0.6 m. When 0.3% Cr3C2/0.4% (TaNb) C are added ,the bb of superfine grained hardmetals reach 3790 MPa, the hardness is 91.6 HRA and the alloys’ WC grains are under 0.8 m and have no abnormal grains growth. The vacuum and HIP sintering process is very helpful to enhance properties of superfine cemented carbides with addition agent, especially for alloys with less Co , because vacuum and HIP sintering process can reduce alloys’ porosity effectively .During the sintering process, the inhibitor will impede the densification of alloys’ solid-phase sintering and decrease liquid occurrence temperature.At last, the paper discusses the mechanisms of inhibitors on superfine grained cemented carbides in detail.更多还原