Effect of residual cobalt on cutting edge wear behavior in Polycrystalline Diamond Compact (PDC)

Cobalt, as a metallic binder, plays a critical role in the sintering process of Polycrystalline Diamond Compacts (PDC) and directly influences their final performance, particularly in terms of wear resistance. Consequently, investigating the impact of residual cobalt on the wear resistance of PDC is of significant practical importance. In this study, PDC samples containing 9 % cobalt were prepared via High-Temperature High-Pressure (HTHP) sintering, followed by a decobaltization process that reduced the cobalt content to 1 %. The wear resistance of both non-decobaltized and decobaltized PDC cutters was subsequently tested. The experimental results indicate that residual cobalt does not significantly influence purely mechanical wear. However, as edge wear intensifies and cutting heat accumulates during turning operations, the thermal expansion mismatch between residual cobalt and diamond results in chipping at the edge near the rake face, ultimately leading to a decrease in wear resistance. The decobaltization treatment effectively reduces the residual cobalt content and significantly inhibits the initiation and propagation of micro-cracks along the cutting edge, thereby enhancing the wear resistance of PDC.