AC-HVAF喷涂纳米结构WC-12Co耐磨涂层的微观结构和性能

Microstructures and properties of nano-structural WC-12Co coatings deposited by AC-HVAF

摘要:

本文采用含纳米WC颗粒的WC-12Co粉末，通过空气助燃超音速火焰喷涂系统（AC-HVAF）制备了耐磨涂层。研究了涂层相组成、微观结构、涂层硬度、断裂韧性和耐磨损性能。X射线衍射分析结果表明WC为涂层主相，未发现其他失碳分解产物。涂层孔隙率低于1%，晶粒尺寸为80-100nm，涂层磨光表面硬度平均值1940.3 HV0.3, 横截面平均硬度高达1662.1 HV0.3。使用WC硬质球为摩擦副，载荷1.5kg，工件转速1198r/min干磨条件下，纳米结构涂层的平均失重比微米结构涂层降低40%，且纳米结构涂层摩擦系数为0.26-0.28（微米结构涂层：0.25-0.4），因此纳米结构涂层具有更加优异的耐磨性能。

Abstract:

In this study, WC-12Co powder with nano WC grain size was used to deposit wear resistant coatings by AC-HVAF (Acukote High Velocity Air-Fuel) spray system. The phase compositions and micro-structure of the coatings were examined. The microhardness, fracture toughness and wear resistance were investigated. According to the X-ray Diffraction (XRD) analysis, the principal phase was WC, and its decomposition products were not found. The sprayed coating has a porosity lower than 1% and the grain sizes of coatings were among 80-100 nm which contributed to an average microhardness as high as 1940.3 HV0.3 on the surface and 1662.1 HV0.3 on the cross-section. At the load of 1.5 kg and rotational speed of 1198 r/min of WC counter body, the nano-sized coatings showed a 40% lower average weight loss and a stable friction coefficient of 0.26-0.28 (micron-sized coatings: 0.25-0.4 ) in the dry wear conditions. It was concluded that the sprayed nano structural WC-12Co coatings had a better wear resistance.