Study On The New Process Of Non-cyanide Cu-Sn Alloy Imitation Gold Plating And Coating Performance

Imitation gold plating has attracted wide attention as a decorative plating to researchers.Copper-tin alloy(Cu-Sn) plating with mature technologies and well corrosion resistantcoating has years of history as a substitute chrome plating, it will have good prospects ifapplied to imitation gold plating. Therefore, the development of a newly non-cyanide Cu-Snalloy imitation gold bath that with the advantages of bath stable, golden color coating andgood corrosion resistance will have a certain social value and economic benefits. It is moresignificant that it can be applied to actual industrial production.In this thesis, the feasibility of non-cyanide imitation gold plating was firstly investigatedthrough Hull cell experiment by changing the bath composition based on previous work, theresults revealed that it cannot be achieved by simply adding other metals. Secondly, the effectof different types of additives on non-cyanide plating Cu-Sn alloy imitation gold plating wasstudied, it found that the condensates of dimethylaminopropylamine and epichlorohydrin(H-3), and quaternary ammonium cations(DDS) had significant effect. Orthogonalexperiment was employed to determine the optimum process of additive H-3 and DDS and toevaluate the effect of each additive on the performance of imitation gold coating, it showedthat additive H-3 was more suitable for imitation gold plating for reasons that it had a fasterspeed of light and the coating was bright, level, even and had excellent corrosion resistance.Then, with tin content(Sn%=13~15%) measured,the basic bath composition and operatingconditions of non-cyanide Cu-Sn imitation gold plating with additive H-3 were determinedthrough orthogonal experiment: Cu2P2O7?3H2O 14~22 g/L, Sn2P2O7 2.0~2.3 g/L, additive H-30.8~1.2 m L/L, K4P2O7?3H2O 240 g/L, current density 0.7~1.0 A/dm2, plating time 4~8 min.The effect of composition and operating conditions on Sn content was investigated by DCelectrolytic experiment, and the corrosion resistance of the coating was characterized by saltspray test, electrochemical test and scanning electron microscopy(SEM) respectively, theresults demonstrated that non-cyanide Cu-Sn alloy imitation gold coating had good corrosionresistance and was a cathodic protective coating compared to the iron substrate. Finally, rackplating experiment was used to examine the color of imitation gold coating on differentintermediate layer(bright nickel layer, bright acid copper, non-cyanide white Cu-Sn), theresults indicated that non-cyanide Cu-Sn alloy imitation gold plating with differentintermediate layers could all obtain a 20 K gold coating and the coating with bright nickel ornon-cyanide white Cu-Sn as intermediate layer was more golden, and non-cyanide whiteCu-Sn intermediate layer is the best with respect to costs.