Study On Electroless Composite Antiwear And Antifriction Coatings Of Ni-P And Ni-W-P Matrix

Mechanical parts failure caused by friction and wear brings great economic losses inmechanical equipment. In order to enhance the surface properties of the device and prolongservice life, antiwear and antifriction micronparticles were deposited on the matrix surface byelectroless composite plating in this paper. The coating obtained in this way could improvewear resistance, antifriction and corrosion resistance of the substrate surface.Ni-P and Ni-W-P matrix micro electroless composite coatings were prepared in thispaper. Ni-P composite coatings included Ni-P-SiC, Ni-P-MoS₂, Ni-P-WS₂, Ni-P-SiC-MoS₂and Ni-P-SiC-WS₂. Ni-W-P composite coatings comprised Ni-W-P-SiC, Ni-W-P-WS₂andNi-W-P-SiC-WS₂. Meanwhile, the parallel experiments of different coatings were completedaccording to the quantity change of added micro particles. Ultimately, microstructure,microhardness, deposition rate and tribological properties were analyzed in detail.By using SEM, EDS and XRD, cellular substance of Ni-W-P matrix compositecoatings had larger volume and denser surface. Micro particles were founded existinguniformly in the corresponding coating. The content of P in every coating varied from5%to10%, and the structure of each coating was amorphous and microcrystalline.The microhardness of the coating changed with the adding amount of micro particles,which increased with the adding SiC micro particles. However, the amount should not be toomuch, the micro hardness of Ni-P-SiC was1180HV when SiC was9g/L, which was1050HVwhen SiC was10g/L. In the coating of single MoS₂or WS₂existing, the microhardnessdecreased with the adding micro particles. Moreover, the coating with WS₂had highermicrohardness. Ni-W-P composite coatings owned higher microhardness than Ni-P compositecoatings when there were the same micro particles. The deposition rate of the coating changedwith the adding micro particles as well. In addition, composite particles deposited moreslowly on Ni-W-P matrix.The tribological performance and corrosion resistance of Ni-W-P and Ni-P matrixcomposite coatings were measured, it was shown that the former was superior to the latterbecause of the presence of W. Furthermore, the coating possessingWS2had better wearresistance, antifriction and corrosion resistance. In the compostite coatings of Ni-P and Ni-W-P, coatings of the smallest wear loss respectively were Ni-P-SiC-WS₂andNi-W-P-SiC-WS₂, coatings of the minimum friction coefficient separately were Ni-P-WS₂and Ni-W-P-WS₂.