金刚石复合片的界面形态及性能特点

INTERFACE CONFORMATIONS OF POLYCRYSTALLINE DIAMOND COMPACT AND THEIR PERFORMANCES

聚晶金刚石复合片的失效主要发生在金刚石与基体之间的界面处 ,改变界面的化学组分和形状可以改善复合片的使用性能。本文介绍了几种优质复合片的界面形态及其性能特点。在金刚石层与基体之间添加镀碳的钨片 ,或在金刚石层外镀上几层金属 ,可以改善金刚石与基体的不匹配问题 ;在基体上加工出沟槽或锯齿 ,使复合片抗冲击性能显著提高 ;为了避免直线型沟槽的方向性以及降低在尖端出现的应力集中 ,将沟槽或锯齿做成环形并使其尖角改成光滑的圆角 ;降低锯齿尖端粘结剂的含量 ,可使基体与金刚石的膨胀系数和弹性模量更接近而提高热稳定性 ;把界面做成波浪形 ,并且使界面与复合片的轴线不垂直 ,以此来分散应力。

The failure of polycrystalline diamond compacts (PDC) mainly occurs as delamination between the diamond and the substrate, thus the performances of a PDC can be improved by optimizing the composition or the shape of the interface. In this paper, design and performance characteristics of some advanced PDC interface samples are overviewed. By adding a thin layer of carbon coated tungsten in between the diamond and the substrate, or coating a metal multilayer on the diamond, the match condition between the diamond and the substrate can be improved. By segmenting or grooving the interface, the impact resistance of a PDC can be improved. By making the segmented or grooved interface into circle shape and changing the critical point into round, the directivity in the liner grooves and the stress concentration can be reduced. By reducing the cobalt metal binder content in the saw-tooth point, the thermal expansion coefficient difference between the diamond and the substrate can be reduced and therefore the thermal stability of the interface can be improved. By changing the interface between the diamond and the substrate into the form of undulating sinusoidal wave and out of perpendicular to the axis of a PDC, the stress at the interface can be sufficiently distributed.