Effect of Pretreatment on Electroless Ni-P Plating Quality of Magnesium Alloy

The effects of pretreatment including surface conditioning and activation and zinc dipping on the electroless Ni-P plating quality of AZ31 magnesium alloy were investigated by microstructure analysis and property test.The surface conditioning could improve the bond strength between electroless Ni-P plating and magnesium matrix,resulted from the projection of grain boundaries and the decrease of surface roughness of magnesium matrix.The electroless Ni-P plating of AZ31 magnesium alloy was promoted owing to the formation of crystal nucleus of elemental zinc through zinc dipping for Ni-P coating.The Ni-P coating was even,dense and had good bond strength when the pretreatment including surface conditioning,activation,zinc dipping,deplating and twi-zinc dipping was adopted before electroless Ni-P plainting.The corrosion resistance and micro hardness of AZ31 magnesium alloy were improved by electroless Ni-P plating.