Effects of multiple ligand coordinations on electroless nickel plating on magnesium alloys

AbstractThe effects of various ligands in the bath on electroless nickel plating on magnesium alloy were investigated to improve the qualities of coating and the bath stability and to decrease the plating temperature. A scanning electronic Microscopy is employed to characterise the surface morphology and an energy dispersed X-ray spectrometer is used to measure the phosphor content. Corrosion resistance and adhesion of the coating are assessed by 5% NaCl solution for 30 h and by thermal shock test, respectively. The results show that the Ni–P coating plated at 70°C in the pH 5·5 ternary ligand bath has higher coverage and better compactness. The ternary combination of citric acid, succinic acid and glycine in the plating solution has obvious synergic effects in improving the coating qualities and the bath stability. The plating temperature is successfully receded to 70°C.