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以WC、Ni及Cr粉末为原料,采用传统粉末冶金方法制备了WC-9Ni-x Cr系列硬质合金。利用扫描电镜、X射线衍射仪、机械性能检测设备和浸泡腐蚀测试方法等观察和表征了试样的微观结构、物理机械性能和耐浸泡腐蚀性能。结果表明:Cr的添加量对WC-9Ni硬质合金的微观结构与性能有着显著地影响。微量的Cr添加后,合金的WC晶粒长大被抑制,晶粒尺寸出现下降;同时,合金的密度、抗弯强度下降,而硬度和耐中性水浸泡腐蚀性能(根据国际标准BS:6920:2000)得到提升。随着Cr添加量的进一步增加,合金的晶粒尺寸、密度、硬度、强度和耐腐蚀性能等变化趋势放缓。另外,根据XRD、SEM和EDX等检测结果发现:过量的Cr粉添加后,WC-9Ni硬质合金的结构中倾向于形成一种新相—(Wx,Cr(1-x))2C,这种新相易成为合金的断裂源。综合合金的微观结构和各项性能检测分析认为:当Cr粉添加量为1.2%(质量分数)时,WC-9Ni硬质合金具有相对最佳的综合性能。
WC-9Ni-x Cr series cemented carbide was prepared by traditional powder metallurgy method using WC, Ni and Cr powders as raw materials. The microstructure, physicomechanical properties and resistance to immersion corrosion of the samples were observed and characterized by scanning electron microscopy, X-ray diffraction, mechanical properties testing equipment and immersion corrosion testing methods. The results show that the addition of Cr has a significant effect on the microstructure and properties of WC-9Ni cemented carbide. When adding a trace amount of Cr, the WC grain growth of the alloy is suppressed and the grain size decreases; at the same time, the density and the bending strength of the alloy decrease, while the hardness and resistance to neutral water immersion corrosion (according to the international standard BS: 6920 : 2000) is improved. With the further increase of Cr addition, the variation tendency of the grain size, density, hardness, strength and corrosion resistance of the alloy slowed down. In addition, the results of XRD, SEM and EDX showed that the WC-9Ni cemented carbide tended to form a new phase of (Wx, Cr (1-x)) 2C New kinds of easy to become alloy fracture source. The microstructure and properties of the alloy show that the WC-9Ni cemented carbide has the best overall performance when the Cr content is 1.2% (mass fraction).