烧结压力对整体PCBN刀具微结构与性能的影响及作用机理

将粒度尺寸5 μm的CBN微粉与黏结剂Al的混合粉末在国产六面顶压机上高压烧结制备整体PCBN材料，通过对样品磨耗比、显微硬度的测试与分析获得了较优的烧结工艺参数:烧结压力5.4 GPa、烧结温度1500℃和烧结时间240 s。测得样品的显微硬度为3897HV5（加载时间15 s），磨耗比为8750。SEM、TEM观察和XRD衍射分析表明:提高烧结压力可使CBN颗粒产生一定的塑性流动，抑制烧结过程中CBN颗粒表面逆转成hBN；黏结剂Al可与CBN颗粒表面反应形成中间产物AlN和AlB₂，在CBN颗粒之间形成牢固的陶瓷中介结合，并消除CBN烧结过程中残余的hBN，从而提高整体PCBN刀具的性能。 

Effect and mechanism of sintering pressure on microstructure and property of solid PCBN tools

The whole polycrystalline cubic boron nitride (PCBN) tools were prepared by high temperature and high pressure sintering with size 5 μm CBN and binder Al powders on the domestic cubic press.The optimum sintering parameters were obtained by testing and analyzing the wear ratio and microhardness of samples. The sintering pressure was 5.4 GPa, the sintering temperature was 1500℃ and the sintering time was 240 s with hardness of 3897HV5 (loading time 15 s). The microhardness of the sample are HV3897, and the wear ratio was 8750. SEM, TEM observation and XRD analysis show that increasing of sintering pressure can make CBN particles produce a certain plastic flow, and inhibit the surface of CBN particles to reverse into hBN during sintering process. The binder Al can react with the surface of CBN particles to form the intermediate products AlN and AlB₂, which can form a solid ceramic bond between CBN grains and eliminate the residual hBN during sintering, thus improving the performance of the integral PCBN tool.