Corrosion resistance of copper deposits produced from different electrolytes

Plating of steel components with copper prior to nickel and chromium plating is of commercial importance. Copper is used as a pre-plate for improved adhesion of the subsequent deposit. It is also employed to prevent case hardening on selected areas of ferrous metal surfaces. Attempts have been made to carry out copper deposition from a sulphamate electrolyte using an optimised bath composition and operating conditions. Alkaline EDTA, conventional cyanide and acid-sulphate baths have also been used for comparative studies. In the present work the corrosion resistance of copper deposits from these electrolytes has been studied using potentiostatic polarisation techniques, A.C. Impedance spectroscopy and weight loss measurements. Although the deposits from different baths indicate good corrosion resistance, the sulphamate bath gives the most highly corrosion resistant and low porosity deposit.