液相烧结法聚晶金刚石微观结构及其力学性能研究

Study on Microstructure and Mechanical Properties of Polycrystalline Diamond by Liquid Sintering Method

笔者在高温高压条件下,以粒度为5μm的金刚石微粉为原材料,采用液相烧结法制备了聚晶金刚石拉丝模坯,分别研究了烧结温度和烧结时间,对其微观结构以及力学性能的影响,最后探讨了PCD拉丝模坯材料的烧结过程和机理。结果表明:聚晶金刚石拉丝模坯的力学性能(磨耗比、维氏硬度)均随着烧结时间的增大先增加后降低,在烧结时间为180s时达到最大,烧结时间过短,其微观组织孔隙较大,烧结时间过长,金刚石石墨化严重;而在以烧结温度为变量的对比实验中发现,聚晶金刚石拉丝模坯的力学性能随着烧结温度的增加先变大后减小,在烧结温度为1550℃时达到最大,烧结温度过低,金刚石晶粒棱角分明,晶粒间隙较大,而烧结温度过高,晶粒发生异常生长。所以,在压力为5.7GPa,温度为1550℃,烧结时间180s的条件下进行液相烧结得到的聚晶金刚石的力学性能最佳。

In this paper, the polycrystalline diamond was sintered under high temperature and high pressure with the diamond powders (5 μm) using liquid sintering method, and the effects of the sintering temperature and sintering time to the microstructure and the properties of the polycrystalline diamond were studied. The results showed that the mechanical properties (abrasion ratio, vickers hardness) of polycrystalline diamond wire drawing die materials increased with the increasing of sintering time and sintering temperature firstly, and then decreases, and the mechanical properties (abrasion ratio, Vickers hardness) reached its maximum when the sintering time was 180 s and 1 550 ℃ respectively, and the pores were more larger when the sintering time is too short, and the diamond graphitization more serious when the sintering time is too long. The grain angular and the grains gap was large when the sintering temperature was too low, while abnormal grain growth could be occurred when the sintering temperature was too high. Therefore, the polycrystalline diamonds with the most outstanding performance were sintered under the conditions of sintering time 180 s, the pressure 5.7 GPa, the temperature 1 550 ℃.