缸套/活塞摩擦副激光束织构处理镀层的组织及摩擦学性能分析

为提高发动机用缸套/活塞摩擦副的润滑磨损性能,对缸套/活塞摩擦副进行激光束织构处理,之后于含颗粒质MoS2和Al2O3的镍基镀液中在其表面制备镀层,利用MoS2和Al2O3的自润滑功能降低活摩擦副的摩擦作用力,采用扫描电镜、X射线衍射仪及磨损试验研究了镀层的微观组织、成分及摩擦学性能。结果表明:镀层内形成了致密组织结构,其厚度约为35μm;在颗粒质浓度为6 g/L时制得了硬度最大的镀层;随着颗粒质浓度不断上升,制得的镀层内也形成了更高含量的MoS2和Al2O3;在颗粒质浓度6 g/L时,镀层达到最大硬度,磨损率也明显减小;没有经过激光束织构处理的镀层磨损得很严重,划痕较为密集,犁沟也较深,而且犁沟之间存在一定的黏连;经过激光束织构处理所得镀层的划痕深度明显降低,基本看不到犁沟现象。

Analysis on Microstructure and Friction Properties of Laser Texture Coatings on the Surface of Cylinder Liner/Piston Friction Pair

The surface of the cylinder liner/piston friction pair was treated with laser beam and the texture coating was prepared. Then,the coating was treated in the nickle-based plating solution containing MoS2 and Al2O3 particles in order to reduce the friction force of the active friction pair,based on the self-lubricating function of MoS2 and Al2O3. The microstructure and friction properties of the coating were studied by SEM,XRD and friction and wear test. Results showed that a compact microstructure formed in the coating with the thickness of about 35 μm.The coating had the greatest hardness when the particle concentration was 6 g/L. The higher contents of MoS2 and Al2 O3 in the coating were obtained with the increase of the particle concentration. When the particle concentration was 6 g/L,the coating hardness reached the maximum and the wear rate decreased obviously. Whereas,the coating without laser beam treatment was badly worn,and the more scratches formed,as well as the furrows were deeper and there were some connections between the furrows. After laser beam texture treatment,the scratch depth of the coating decreased obviously,and the furrow was hardly observed.