Numerical analysis of mass transport and solution properties of nickel electrodeposited in supercritical CO2

High quality films with fine grains have been reported using the novel plating method which combines the merits of traditional electroplating method with supercritical CO₂ techniques. In the plating system of supercritical CO₂, the optimal model was developed by Econometrics Views (EViews) software according to the effects of working pressures and temperatures on the electric resistance in emulsion, and the diffusion transport model of nickel ions was established according to the micro-trench feature. Matrix Laboratory (MATLAB) software was applied to analyse the optimization and effects. The influences of the current densities and micro-trench depths on nickel ions distribution were discussed, and the experiment of nickel electro depositing with non-ionic surfactant Tergitol TMN 10 was investigated. The results indicate that the system exists an optimum condition for nickel electrodepositing at 16.0128 MPa and 44.9685°C, then the resistance of emulsion is 23.4753 Ω. Under the same conditions, the effect of working pressure on the resistance of emulsion is more significant than that of working temperature. For an aspect ratio of 4, the nickel ions mass transport gradually approach a steady state with the depositing time increasing. The higher uniformity and smoother surface of nickel plated films can be obtained in supercritical CO₂ at 10 MPa and 50°C, the average Vickers hardness of nickel films is 701.2 Hv.