304不锈钢激光原位合成自润滑涂层的宽温域摩擦学性能

由于304不锈钢在中、高温下摩擦学性能较差,制约了其在重要摩擦运动副零部件上的应用。为改善304不锈钢的摩擦学性能,以Ni60粉末为增韧相,WS2为合成润滑相的前驱化合物,TiC为高硬度耐磨相,采用高能激光束在其表面原位合成自润滑耐磨复合涂层。利用X射线衍射仪、扫描电子显微镜、显微硬度计、摩擦磨损试验机和探针式材料表面磨痕测量仪表征涂层和基体的物相、微观结构、显微硬度与表面形貌,并系统研究涂层和基体在20,300,600,800℃下的摩擦学性能及其磨损机理。结果表明:涂层主要由Cr0.19Fe0.7Ni0.11,Ti2SC,Fe2C,Cr7C3,CrS和WS2组成;涂层的平均显微硬度(302.0HV0.5)略高于基体(257.2HV0.5),但涂层上部区域的硬度(425.4HV0.5)约为基体的1.65倍;涂层在所有等温摩擦学实验中摩擦因数和磨损率均低于基体,300℃时涂层润滑效果最好,摩擦因数为0.3031,600℃时涂层耐磨效果最好,磨损率为9.699×10^-5 mm^3·N^-1·m^-1。

Wide temperature range tribological performance of laser in-situ synthesized self-lubricating coating on 304 stainless steel

304 stainless steel has poor tribological properties at medium and high temperatures, severely limiting its application to the important frictional motion auxiliary parts. In order to improve the tribological properties of 304 stainless steel,Ni60 powder was used as toughening phase,WS2 acted as precursor for synthetic lubricating phase,TiC used as high-hardness and wear-resistant phase,and high-energy laser beam was used to in-situ synthesize a self-lubricating and anti-wear composite coating on its surface. The phase compositions, microstructure,microhardness and surface topogr-aphies of the coating and substrate were characterized by XRD,SEM,microhardness tester,friction and wear tester and the probe-type surface profilometer, and the tribological properties as well as the corresponding wear mechanisms of the coating and substrate at 20,300,600,800 ℃ were systematically studied. Results indicate that the coating is mainly composed of Cr0.19Fe0.7Ni0.11,Ti2SC,Fe2C,Cr7C3,CrS and WS2. Although the average microhardness of the coating(302.0 HV0.5) is slightly higher than that of the substrate(257.2 HV0.5), the hardness of the upper region of the coating(425.4 HV0.5) is about 1.65 times that of the substrate. The friction coefficients and wear rates of coating are lower than that of the substrate at all the isothermal tribological experiments. The coating possesses the best lubrication effect at 300 ℃ with friction coefficient of 0.3031, and the best wear resistance at 600 ℃ with a wear rate of 9.699×10-5 mm3·N-1·m-1.