化学镀法制备低钴含量WC-Co复合粉体及其放电等离子烧结  

Preparation of low Co-coated WC composite powder by electroless plating and its sintering by spark plasma sintering process

作　　者：王金芳[1,2] 左敦稳[1] 朱流[2] 涂志标[2] 戴晟[2] 

机构地区：[1]南京航空航天大学机电学院,江苏南京210016 [2]台州学院机械工程学院,浙江台州318000

出　　处：《材料热处理学报》2016年第3期12-17,共6页Transactions of Materials and Heat Treatment

基　　金：浙江省高等学校中青年学科带头人学术攀登项目(pd2013416);浙江省教育厅科研项目(Y201430375);江苏省普通高校学术学位研究生科研创新计划项目(KYLX_0228)

摘　　要：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。Low Co（ ≤1mass%）-coated tungsten carbide（ WC） composite powder was synthesized by ultrasonic-assisted electroless plating with chemical activation pretreatment before the plating,and then it was applied in preparation of WC-based cemented carbides by spark plasma sintering. The influence of the chemical activation pretreatment on electroless cobalt plating and a small amount of uniform distribution of cobalt on the densification behavior,microstructure and mechanical properties of the sintered samples was investigated. The results show that a large number of lattice defects such as dislocations and stacking fault exist in the surface of the WC powder after chemical activation pretreatment. Lattice distortion and stress field around the defects which has large surface energy reduces the interface contact angle and improves the wettability between metal and ceramic,meanwhile the nucleation energy is decreased and the process of electroless cobalt plating is realized. The uniform distribution of cobalt in WC-Co composite powder accelerates the sintering densification process,and is beneficial to improving the mechanical properties of the sintered sample compared with the binderless one. The density of WC-based cemented carbides synthesized with low Co-coated WC composite powder is up to 15. 56 g / cm^3 with the final sintering temperature of 1500℃. The hardness and fracture toughness are 2409 HV30 and 9. 2 MPa·m^1 /2,respectively.

关 键 词：化学镀法 WC-Co复合粉体 放电等离子烧结 化学活化 力学性能 

分 类 号：TG135.5[一般工业技术—材料科学与工程]