超细WC-Co硬质合金及其磨损性能研究

Preparation of ultra-fine WC-Co cermet and its wear behavior

采用低温化学镀方法在超细WC颗粒表面进行金属钴包覆,烧结包覆后的复合粉体制备新型硬质合金NYG(WC-3%Co)。研究了超细WC-Co硬质合金的力学性能、断口形貌和显微结构,在销盘式磨损试验机上进行干滑动磨损实验。结果表明,在硬质合金烧结过程中,沿WC晶界均匀分布的金属钴不仅起粘结剂作用,也起抑制剂作用阻碍晶粒的长大;新型硬质合金的抗弯强度、断裂韧性、硬度和耐磨性能均得到较大提高;在干滑动摩擦条件下,新型WC-Co硬质合金的失效以塑性变形及细小碳化钨相颗粒脱落为特征。

Coating of cobalt on surface of ultra-fine WC particle to form WC-Co composite powder was carried out by low temperature electroless plating. The WC-Co composite powder was sintered into a new type of ultra-fine WC-Co cemented carbide (NYG). The mechanical properties of the NYG were tested. The scanning electron microscopy (SEM) was used to examined the morphology and microstructure of the samples. The wear tests were performed on a pin-on-disc wear device. The results show that Co, binder phase, distributes along the grain boundary of WC and forms network structure to restrain the grain growth. The bend strength, fracture toughness and hardness of NYG are greatly improved. The plastic deformation and spalling of some WC particles are predominated in the wear process.