Study On Electroplating Of Sn-Ni-Cu Alloy

In this paper,single factor and response surface methods were used to select and optimize the plating process of Sn-Ni-Cu alloy.Then the sample was heated to study the effect of heat treatment on the properties of the coating.Firstly,the basic formula of Sn-Ni-Cu alloy coating prepared by electroplating in the Diphosphate system was optimized.The effects of temperature,p H value,current density,main salt concentration,and potassium pyrophosphate concentration on coating composition were studied by single factor method The influence of the concentration of L-cysteine,ethylenediamine,and triammonium citrate on the gloss and corrosion resistance of the coating,the optimum formula,and parameters of Sn-Ni-Cu electroplating were determined as follows: nickel chloride 33.28 g/l,stannous chloride29.33 g/l,copper sulfate 5 g/L,potassium pyrophosphate 265 g/l,l-cysteine 6 g/L,ethylenediamine 20 ml/L,triammonium citrate 40 g/L,current density 1.3 A/DM2,temperature 40 °C,PH 8.5,time 5 min.The composition of Sn-Ni-Cu alloy coating prepared by this formula is Sn46.10%,Ni47.07%,Cu6.83%.The coating has a uniform surface,no defects,and good adhesion with the substrate,and the properties of the coating have reached the expected target.After getting the best basic formula,the single factor test and the response surface method were used to design the three-level test,and the response value was 60 ° gloss of the coating,the optimum formula of the brightener and Surfactant for Sn-Ni-Cu alloy coating was obtained by optimization analysis: 1.4-butynediol was 0.4 g/L,Saccharin Sodium was 3.5 g/L,thiourea concentration was 0.06 g/L,polyoxyethylene alkylamine0.08 g/L,Triton x-10000.30 g/L,Capstone fs-3100000.30 g/L.The test results show that the performance of the coating made by the additive formula can obviously be improved.The samples of Sn-Ni-Cu alloy coating were prepared by the best plating formula,and then the samples were heat-treated at 400 °c.The results showed that the coating showed the best corrosion resistance,the surface of the coating was smooth and the crystallization was fine,the microhardness and adhesion of the coating were the highest.