镍基碳化钨颗粒增强复合熔覆层的组织结构与摩擦学性能

Microstructure and tribological properties of Ni-based WC particles reinforced composite clad layer

借助激光熔覆方法在H13钢基材上制备不同WC含量的Ni基WC复合熔覆层,采用扫描电子显微镜(SEM)、微区X射线能谱(EDS)和X射线衍射仪(XRD)分析了熔覆层表面的物相、熔覆层与基材的结合情况、熔覆层内部增强相的形貌、成分与分布;在室温下测试显微硬度、摩擦因数和磨损率。结果表明:基体和熔覆层之间为冶金结合,熔覆层物相为γ-Ni相、WC、Cr23C6、W2C相,这些碳化物呈现近圆形;激光熔覆层中Ni基体的显微硬度为550-700 HV0.1,硬质相颗粒的显微硬度为2700~3500 HV0.1,是基材显微硬度的5~7倍;Ni基+30%WC熔覆层的摩擦因数为0.7,磨损率为1.92×10^(-8)mm^3/(N·m)。随着WC含量增多45%,耐磨性进一步提高、摩擦因数约为0.4,磨损率为8.32×10^(-9)mm^3/(N·m),WC含量达到60%,摩擦因数为0.5、磨损率与45%WC熔覆层磨损率接近;综合比较,45%WC激光溶层耐磨减摩效果最佳。

Ni-base clad layers with different content of WC particles reinforced were fabricated on substrate of H13 steel by laser cladding technique. The phase constituents,the bonding characteristics between clad layer and substrate and as well as the morphologies,composition and distribution of reinforced phases were revealed by scanning electron microscopy（ SEM）,energy dispersive X-Ray spectroscopy（ EDS）and X-ray diffraction（ XRD）. The hardness and tribological properties also were analyzed. The presence of good metallurgical bonding characteristics between clad layer and the H13 steel substrate was observed. γ-Ni phase and three carbides（ WC,Cr23C6 and W2C） with spherical shape were also observed in clad layer. The microhardness of Ni-base phase and reinforced phase particles were 550-700 HV0. 1 and2700-3500 HV0. 1,respectively. The friction coefficient and wear rate of the clad layer with 30% WC were 0. 7 and 1. 92 × 10^-8mm^3/（ N·m）,respectively. Adding 45% WC into clad layer,friction coefficient was decreased to 0. 4 and wear rate was declined to 8. 32 × 10^-9mm^3/（ N·m）. When 60% WC added into clad layer,the friction coefficient was 0. 5 and wear rate was close to that of the clad layer with 45%WC. The preferable tribological properties were achieved for the clad layer with 45% WC.