HVOF喷涂角度对NiCrBSi涂层组织结构及摩擦学性能的影响

Effects of HVOF Spraying Angle on Microstructure and Tribological Properties of NiCrBSi Coatings

采用HVOF工艺制备了40°、50°、60°、70°、80°、90°六种不同喷涂角度的NiCrBSi涂层,对涂层微观形貌、孔隙率、显微硬度,以及25、400、600℃下的摩擦磨损性能进行了研究。结果表明:不同喷涂角度制备的涂层的微观结构不同,喷涂角度为40°、50°时,制备的涂层内未见未熔/半熔颗粒;喷涂角度达到60°及以上时,制备的涂层内出现未熔/半熔颗粒,且沉积效率有明显提升。涂层显微硬度在50°及90°喷涂角度时达到最大值837.2 HV_(0.1)。同种涂层的平均摩擦因数随着试验温度的升高而降低;在常温状态下,50°喷涂角度制备的涂层磨损率最低;当磨损试验温度上升至400℃及600℃时,90°喷涂角度制备的涂层的磨损率最低。涂层在25℃及400℃下的磨损机理主要表现为疲劳磨损,在600℃时,90°喷涂角度制备的涂层表现出磨粒磨损特征。与喷涂角度40°制备的涂层相比,喷涂角度90°制备的涂层中的未熔/半熔颗粒起到“钉扎效应”,有助于提高涂层在常温和高温环境下的耐磨性。

Six kinds of NiCrBSi coatings with different spray angles of 40°,50°,60°,70°,80°and 90°were prepared by HVOF technology.The microstructure,porosity,microhardness,and wear properties of the coatings at 25℃,400℃and 600 were studied.The results show that the microstructure of coatings prepared from different spraying angles id different.When the spraying angle are 40°and 50°,there are no unmelted/semi-melted particles in the coating.When the coating angle reaches 60°or above,there are unmelted/semi-melted particles in the coating,and the deposition efficiency is significantly improved.The microhardness of the coating reaches its maximum value of 837.2 HV_(0.1) at spray angles of 50°and 90°.The average friction coefficient of the same coating decreases with the increase of test temperature.At room temperature,the wear rate of the 50°spray coating is the lowest.When the wear test temperature rises to 400℃and 600℃,the wear rate of the 90°spray coating is the lowest.The wear mechanism of the coating at temperatures of 25℃and 400℃is mainly manifested as fatigue wear,and at 600℃,the 90°spray coating exhibits abrasive wear characteristics.Compared with the coating prepared by the spraying angle of 40°,the unmelted/semi-melted particles in the coating prepared by the spraying angle of 90°play a“pinning effect”,which helps to improve the wear resistance of the coating both at room temperature and high temperature environments.