Acidic electroless Ni-P plating on sintered Nd-Fe-B magnet

After degreasing,pickling,sealing,activating and strike plating,Ni-P alloy was deposited on the surface of Nd-Fe-B magnet.The properties of Ni-P deposit at different plating time were tested.X-ray and SEM test indicate that the Ni-P deposit is bright and compact and has amorphous structure,with phosphorus content of 12.1%.The corrosion potential,corrosion current density and corrosion rate of Nd-Fe-B magnet and Ni-P deposit were determined with polarization curve,and seawater immersion test was conduceted.The results show that the corrosion potential of Ni-P deposit is higher than that of Nd-Fe-B deposit,and the sealing can improve its corrosion resistance.The deposit can remarkably improve the corrosion resistance of Nd-Fe-B magnet,and the corrosion resistance increases with increasing the deposit thickness.