采用化学包覆法制备WC-(8Co,2Ni)-xMo (x为质量分数,%。x=0,0.5,1.0,1.5)复合粉末,真空烧结后得到含Mo的WC-(8Co,2Ni)硬质合金。研究前驱体和复合粉末的微观形貌和物相组成,分析Mo对WC-(8Co,2Ni)硬质合金显微组织、力学性能和耐腐蚀性能的影响。结果表明,WC-(8Co,2Ni)-xMo复合粉末中的Mo均匀分布在WC颗粒表面。WC-(8Co,2Ni)-xMo硬质合金较致密,无明显孔洞,WC和黏结相无明显聚集。随Mo质量分数从0增加至1.5%,WC晶粒的平均尺寸从1.6 μm减小至1.1 μm。合金硬度(HRA)从87.3±0.1提高至88.3±0.2,抗弯强度从(2 890±27) MPa下降至(2 560±29) MPa。含Mo合金在腐蚀过程中生成低电导率的含Mo钝化膜,耐腐蚀性能明显提升。
In this work, the WC-(8Co,2Ni)-xMo (x=0, 0.5, 1.0, 1.5, mass fraction,%) composite powders were successfully prepared by chemical coating method, and then the WC-(8Co,2Ni)-xMo cemented carbides were fabricated by vacuum sintering method. The microstructure and phase composition of precursors and composite powders were studied. The effects of Mo on the microstructure, mechanical properties and corrosion resistance of WC-(8Co,2Ni) cemented carbide were investigated. The results show that the Mo in the WC-(8Co,2Ni)-xMo composite powders is uniformly distributed on the surface of the WC particles. The WC-(8Co,2Ni)-xMo cemented carbides are density, and have no obvious pores, WC and binder distribute uniformly. As the mass fraction of Mo increases from 0 to 1.5%, the average grain size of WC decreases from 1.6 μm to 1.1 μm. The hardness (HRA) of the alloy increases from (87.3±0.1) to (88.3±0.2), and the bending strength decreases from (2 890±27) MPa to (2 560±29) MPa. The low conductivity Mo-containing passivation film is formed during the corrosion process, so the corrosion resistance of the alloys is significantly improved.
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