Influence of Main Salt and Reducing Agent to Nickel-phosphorus Alloy on AZ31 Magnesium Alloy

Electroless plating nickel-phosphorus alloy coating was conducted on the magnesium alloy,using plating solution system with nickel sulfate as the main salt and sodium phosphate as the reducing agent.The influences of the main salt and reducing agent molar concentration ratio on the morphology,composition,deposition rate and corrosion resistance of nickel-phosphorus coatings were discussed by SEM,EDS,metallographic analysis and polarization curves.The results show that the coatings retain the same morphology at different molar concentration ratios.However,the phosphorus content linearly decreases with increasing main salt and reducing agent molar concentration.The deposition rate is the fastest while the main salt and reducing agent molar concentration ratio is in the range of 0.4-0.6.The coating has good corrosion resistance while the molar concentration is 0.3or 0.4.From the above,the coatings,electroless-plated with the main salt and reducing agent molar concentration ratio of 0.4,have the best comprehensive performance,in only considering the effects of main salt and reducing agent on coating performance