A Study Of Ni-SiC Nano-Composite Plating Process

Composite plating is a direct and effective way to optimize the surface of common metal material with the characters of high hardness and high erode-resistant. Nanometer material is superior to common materials in its physical and chemical characters. The emergence of nanometer material brings a new development to composite plating. If nanoparticles are applied in composite plating, the technique is applied universal importance inside and outside.So in this paper, it makes well composite coatings by composite plating as the research object. It is analyzed the technique and properties of Ni/nano-SiC composite coating. The main researches and results were as follows:First, the effects of hardness, deposition rate and erode-resistant of composite coating in cathode current density, SiC concentration in electrolyte, pH, temperature and stirring rate were analyzed by single factor test.Then, the best process parameters were determined by orthogonal test. The optimized process parameters are pH: 4, SiC: 5g/L, cathode current density: 5 A/dm~2, stirring rate: hit by high speed, temperature: 50℃. The results show that Ni/nano-SiC composite coating has a flat morphology and compact microstructure, and its micro-hardness is remarkably improved compared with that of pure nickel coating.Finally, the mechanism was studied by Cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS). The results show that the addition of nano-SiC particles into electroplating solutions, the nano-SiC will arrive at the cathode surface, which will simultaneously result in the incorporation of. nano-SiC into nickel matrix and increase the cathode polarization. Meanwhile the engulfed nano-SiC will stop the growth and congregation of existing crystalline the nucleation rate of new grains synchronously. Accordingly, the formation velocity of crystal grains will exceed the growing velocity, which results in aflat morphology and compact microstructure.