Study On Technologies And Performance Of Ni-p Composite Plating Enhanced By Pre-treatment Of Sic Particles

Ni-P-SiC composite plating is a technology to form composite coatings with high hardness and high wear resistance, in which insoluble SiC particles are added and dispersed in plating solution to realize the codeposition of SiC particles and Ni-P base metal. The performances of composite coatings depend on many factors such as the distribution of particles and the particles content in composite coatings, while the particle deposition depends on the dispersion of particles in the chemical plating bath. But how to get a good deposition of SiC particles in the solution still remains a focus for researchers.Three pretreatment methods such as HCl activation, surface active agents and pre-plating are used to change the surface morphology of SiC particles, and then composite plating experiments are performed by adding the particles into composite plating solution, respectively. The appearance and microstructure of coatings are observed by XJP-6A type metallurgical microscope. The bonding strength between coatings and the matrix is determined by bending tests. The micro hardness of coatings is measured by HVS1000 type digital micro hardness tester. The porosities of coatings are determined by posts filter paper method. The morphology of coatings is observed by SEM, and elements were analyzed by EDS. Results show that, better dispersion of SiC particles in the chemical plating solution are achieved by adding the pretreated SiC particles using all the three methods into Ni-P-SiC composite plating. The particles are evenly distributed in coatings and better composite quantities are obtained. Among the three methods, the plating coatings obtained by adding pre-plating particles have the best performance. The MPX-2000 type plate pin friction and abrasion tester is modified, which made the abrasion test of the tester more convenient and efficient. The wear resistances of composite coatings obtained with different treatment methods are tested by this modified tester. The cause of coatings with good abrasion performance and the abrasion mechanism of the coatings are investigated. Comparison between test results indicates that the composite coatings with the best wear resistance are obtained by adding pre-plating SiC particles.