以cBN, TiC, Al为主要实验原料, 利用高温和超高压条件合成聚晶立方氮化硼(PCBN)复合材料。利用X射线衍射(XRD)、扫描电子显微镜(SEM)以及X射线 色散能谱(EDS)对复合材料的物相组成、显微结构、表面微裂纹以及各类元素分布情况进行了分析, 同时对复合材料的显微硬度和抗弯强度进行了测试。研究 表明: 在超高压5.5 GPa, 高温1 450 ℃下, PCBN烧结体由BN, TiC, AlB2和AlN组成; 结合剂均匀的分布在cBN颗粒周围, 牢固的将cBN颗粒粘结在一起。PCBN 的硬度随着cBN含量的增加而显著增加, 抗弯强度则是先增大后减小, PCBN的断裂方式是沿晶断裂和穿晶断裂共同作用的结果。

Using cBN, TiC and Al as main experimental materials, polycrystalline cubic boron nitride (PCBN) composites were synthesized at high temperature and ultrahigh pressure conditions. The phase composition, microstructure, surface microcracks and various elemental distributions of the composites were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray dispersive spectroscopy (EDS). The microhardness and flexural strength of the material were tested. The research shows that the PCBN sintered body is composed of BN, TiC, AlB2 and AlN at an ultrahigh pressure of 5.5 GPa and a high temperature of 1 450 ℃. The binder is uniformly distributed around the cBN particles, and the cBN particles are firmly bonded together. The hardness of PCBN increases remarkably with the increase of cBN content and the flexural strength increases first and then decreases. The fracture mode of PCBN is the result of the combination of intergranular fracture and transcrystalline fracture.