HVOF和APS制备WC-Co/NiCrBSi复合涂层高温摩擦学特性研究

Research on Tribological Properties of WC-Co /NiCrBSi Composite Coatings Prepared by HVOF and APS at Elevated Temperature

运用超音速火焰喷涂(HVOF)和等离子喷涂(APS)技术在7005铝合金表面制备了WCCo/NiCrBSi复合涂层,分析了2种技术所制备复合涂层的微观结构,研究了其在高温条件下的摩擦磨损行为与机制。结果表明:采用HVOF技术制备的复合涂层孔隙率仅为APS制备复合涂层的28.9%;其显微硬度(838.4HV0.5)以及与基体间元素扩散层厚度(Al:13.17μm,Ni:12.55μm)均高于APS制备的复合涂层。不同温度条件下,HVOF制备复合涂层的摩擦系数和磨损失重均低于APS制备复合涂层。室温25℃时,HVOF制备复合涂层以微观切削磨损和轻微的疲劳磨损为主,而APS制备的复合涂层则主要为疲劳断裂磨损;高温400℃条件下,前者的磨损机理变为多次塑变磨损和氧化磨损,而后者则为严重的粘着磨损和氧化磨损。

WC-Co/NiCrBSi composite coatings were prepared on the surface of aluminium alloy 7005 by high velocity oxygen-fuel flame （HVOF） spray and atmosphere plasma spray （APS）, respectively. The microstructures of the composite coatings are analyzed, and the tribological behavior and mechanisms of the composite coatings at elevated temperature are researched. The results show that the porosity of the composite coatings prepared by HVOF is only 28.9% of that prepared by APS. The microhardness of the composite coatings prepared by HVOF is 838.4HV0.s , and the thicknesses of A1 and Ni diffusion layers are 13.17 p,m and 12. 55 p,m, respectively, which are all higher than those of the composite coatings pre- pared by APS. The composite coatings prepared by HVOF have low friction coefficient and wear loss com- pared with the composite coatings prepared by APS. At room temperature of 25 ~C, the wear mechanisms of the composite coatings prepared by HVOF are micro-cutting wear and slight fatigue wear, and the composite coatings prepared by APS experience fatigue fracture wear. At elevated temperature of 400 ℃ , the wear mechanisms of the former change into multi-plastic deformation wear and oxidative wear, and those of the latter turn into severe adhesive wear and oxidative wear.