Exploring environment friendly nickel electrodeposition on AZ91 magnesium alloy: Effect of prior surface treatments and temperature of the bath on corrosion behaviour

The nickel electroplating of AZ91 magnesium alloy was explored with and without employing surface pretreatment. The plating process refrained from using hazardous elements namely fluoride, chromium and copper or zinc undercoat. The electroplating was achieved at 25–70 °C and 25 mA cm−2 after applying surface pretreatments and Ni-P interlayer. Electrochemical and salt spray tests revealed large enhancement in corrosion resistance of 15 μm thick coating obtained at 70 °C bath temperature. The pretreatment involved phosphoric acid followed by NaOH produced superior coating to nickel carbonate followed by carbonate silicate bath, which is explained based on the porosity and hydrogen activity on the surface.