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对WC粉体进行化学活化预处理,然后采用超声辅助化学镀法制备低钴含量WC-Co(≤1 mass%)复合粉体,采用放电等离子烧结(SPS)技术,制备了少粘结相WC-Co硬质合金材料。研究了化学活化预处理工艺对WC粉体表面化学镀Co的影响以及少量均匀包覆的Co对试样烧结致密化过程、显微组织结构及力学性能的影响。试验结果表明:化学活化预处理后的WC粉体出现了大量的层错、位错等缺陷,在缺陷周围产生点阵畸变和应力场,较大的表面能减小了金属与陶瓷界面接触角,提高了二者之间的润湿性,降低了化学镀过程的形核功,实现化学镀钴过程;与纯WC粉体烧结试样相比,少量Co在WC-Co复合粉体中的均匀分布,大大降低了烧结温度,促进了粉体烧结致密化进程,各项性能得到显著提高,密度达15.56 g/cm3,硬度为2409 HV30,断裂韧性为9.2 MPa.m1/2。
The WC powder was pretreated by chemical activation, and then WC-Co (≤1 mass%) composite powder with low cobalt content was prepared by ultrasonic assisted electroless plating method. Spark plasma sintering (SPS) -Co cemented carbide material. The effect of chemical activation pretreatment on the electroless plating of Co on the surface of WC powder and the influence of Co on the sintering densification, microstructure and mechanical properties of the sample were studied. The experimental results show that a large number of defects, such as stacking faults and dislocations, occur in the WC powder after chemical activation pretreatment, which results in lattice distortion and stress field around the defects. The larger surface energy can reduce the contact angle between the metal and the ceramic interface , Improving the wettability between the two, reducing the nucleation work of the electroless plating process and realizing the electroless cobalt plating process. Compared with pure WC powder sintered samples, a small amount of Co in the WC-Co composite powder Uniform distribution, the sintering temperature is greatly reduced, the densification process of the powder is promoted, and the properties are remarkably improved. The density is 15.56 g / cm3, the hardness is 2409 HV30 and the fracture toughness is 9.2 MPa.m1 / 2.