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Si-Ti-B 掺杂烧结金刚石/硬质合金复合体中金刚石层的抗弯强度和耐磨性取决于金刚石粒度和掺杂量两种因素。本文将抗弯强度、耐磨性与金刚石粒度、掺杂量的关系归结为性能与平均自由路程的关系。在性能与平均自由程的关系曲线中存在性能最佳值。在曲线的左支,抗弯强度(或耐磨性)随平均自由程(粘结相层厚度)的减小而降低。这是由于存在金刚石直接接触的弱区而造成的。在曲线的右支,抗弯强度随粘结相层厚度增大而降低,强度和硬度都低于金刚石的粘结相(SiC、TiC、TiSi_2),降低了烧结金刚石的整体强度。只有当粘结相层厚度适中时,才能发挥出金刚石固有的良好强度和耐磨性。
The flexural strength and wear resistance of diamond layers in Si-Ti-B doped sintered diamond / cemented carbide composites depend on two factors: diamond particle size and doping amount. In this paper, the relationship between flexural strength, wear resistance and diamond particle size and doping amount is attributed to the relationship between performance and mean free path. The best performance value exists in the performance vs. mean free path curve. At the left branch of the curve, the flexural strength (or wear resistance) decreases with decreasing mean free path (binder phase thickness). This is due to the presence of weak areas in direct contact with the diamond. On the right branch of the curve, the flexural strength decreases with the increase of the thickness of the binder phase, which is lower than that of the diamond binder phase (SiC, TiC, TiSi_2) and decreases the overall strength of the sintered diamond. Only when the thickness of the binder phase is moderate can the inherent good strength and wear resistance of the diamond be exerted.