The role of original diamond grain size in the tribological behaviors of the 700 °C annealed polycrystalline diamond (PCD) is discussed in view of experimental studies using complementary analytical techniques (SEM&EDS, TGA-DSC, XRD and Raman). The original diamond grain size has a strong effect on the tribological behaviors of the annealed PCD, which can be accounted for by the various cobalt content and distribution shape. The annealed PCD with the original diamond grain size of 2 μm possesses the lowest cobalt content and presents severe abrasive wear, which is due to the plowing action of exfoliated diamond grains. During the annealing treatment of PCD with large original diamond grain, the large amount of leaf-like distributed cobalt facilitates the diamond graphitization by the catalytic action, which accelerates the formation of friction reducing carbonaceous transfer film, thus yields to a low friction coefficient. The fully oxidation filling into the spalling inhibits the serious grain exfoliation, thus further prevents the annealed PCD wearing substantially. Overall, the cobalt-catalytic diamond graphitization without an excessive wear resistance sacrifice can be exploited to achieve excellent tribological properties of PCD after 700 °C annealing treatment.

鉴于使用互补分析技术（SEM＆EDS，TGA-DSC，XRD和拉曼）的实验研究，讨论了原始金刚石晶粒尺寸在700°C退火多晶金刚石（PCD）的摩擦学行为中的作用。原始金刚石晶粒尺寸对退火PCD的摩擦学性能有很大影响，这可以通过各种钴含量和分布形状来解释。原始金刚石晶粒尺寸为2μm的退火PCD具有最低的钴含量，并表现出严重的磨料磨损，这是由于剥落的金刚石晶粒的犁action作用所致。在对具有原始大金刚石晶粒的PCD进行退火处理期间，大量叶状分布的钴通过催化作用促进金刚石的石墨化，这加速了减少摩擦的碳质转移膜的形成，因此产生了低摩擦系数。完全氧化填充到剥落中可防止严重的颗粒剥落，从而进一步防止退火的PCD严重磨损。总的来说，在不过度牺牲耐磨性的前提下，可以利用钴催化的金刚石石墨化工艺在700°C退火处理后获得优异的PCD摩擦学性能。