| Silver coating and palladium coating have be wildly used with the development of the electronics industry. In order to improve the resistance of silver coating in sulfur atmospheric environment, save palladium, increase the abrasion resistance, anti-corrosion against sulphide, corrosion resistance and catalytic capability, a Ag-Pd alloy plating process which is based on nickel mesh, corrosion-resistant, heat-resistant and oxidation-resistant in oxygen-rich environment is studied in this paper.The substrates of traditional plating processes are flat copper or silver films which have good adhesive ability. But as for nickel substrate, the adhesive performance of the resulting coating is relatively poor, In order to obtain desirable coatings, we first explored the processes before and after the electroplating and then we developed compound additive A. Finally we studied the effects of complexing agent content and plating parameters(including cathode current density and plating temperature) by single-factor analysis method. The results show that the optimal technological formulation of plating Ag-Pd alloy is determined to be composed of580g/L LiCl,1.31g/L PdCl2,3.11g/L AgNO3, operating temperature60°C, cathode current density0.15A/dm2and pH value2.0. The silver content in the alloy coatings is72.89%, palladium is22.68%, and nickel is4.43%, the thickness of coating is20μm. The brightness of coating reaches the level of grade two and the coating has the features of fine and even grain and good adhesion. The performance test results of the coating and solution showed that the solution is stable with throwing power86.75%and covering power4.53. The coating can be used as a corrosion resistance coating.When using brominated salt-nitrite electroplating Ag-Pd alloy, the coating obtained from the original formula is easy to oxidation and doesn’t withstand high temperature, therefor, on the basis of the original formula, this paper focus on exploration the impact of the process operating parameters and the treatment before and afte plating on the high temperature resistant performance of the coating. Through amount of experiments, it’s found that high temperature resistant performance can be enhanced via prolonging electroplating time and pre-plating. Then, a kind of Ag-Pd alloy coating is developed as antioxidation and anti-high temperature (1100°C) by controlling the time of electro deposition previously8min and plating palladium lh.By orthogonal experiment, the optimized conditions of adopting bromide-nitrite sliver electroplating palladium alloy are obtained. The results show that the optimal technological formulation of plating Ag-Pd alloy is determined to be composed of550g/L KBr,25g/L PdCl2,15g/L AgNO3, the time of electro deposition previously8min, operating temperature60°C, cathode current density0.20A/dm2and pH value6.0. The research shows that plating one hour can be made antioxidation and heat resisting (1100°C) coating. The performance test results of the coating and solution showed that the solution is stable with throwing power75.74%and covering power4.32. |
