Process and performance of electroless nickel plating on AZ91D magnesium alloy

Abstract

Purpose The purpose of the investigation was to research the best process of electroless nickel (EN) plating on AZ91D magnesium alloy and the performance of EN plating coating. Design/methodology/approach Through single factor test and orthogonal test, EN plating on AZ91D magnesium alloy was researched. The plating rate and porosity were analyzed. The coating appearance of EN plating coating and magnesium alloy substrate was evaluated. The electrochemical properties of EN plating coating and substrate were researched using electrochemical workstation, and their compositions and structure were examined using X-ray diffraction and scanning electron microscopy. Findings The results made by combination of experimental and orthogonal test showed that the best formula of EN plating was 8.8 g·L−1 nickel ion, 25 g·L−1 lactic acid, 28 g·L−1 reducing agent, 1.8 ml·L−1 corrosion inhibitor, 1 mg·L−1 stabilizer, temperature at 85°C and pH value at 5.5. The plating was uniform, dense and with no cracks. The electrochemical tests showed that the corrosion resistance of EN plating was better than that of magnesium alloy substrate. Originality/value The results indicated that the corrosion resistance of magnesium alloy improved markedly after EN plating at the best formula and the plating covered magnesium alloy completely.