Effect of HEDP concentration on alkaline cyanide-free copper electroplating of sintered NdFeB
[Introduction]Sintered neodymium-iron-boron(NdFeB)magnets are increasingly used in acousto-electromagnetic parts,it is necessary to conduct some effective surface treatments to improve their corrosion resistance and service lives.[Method]Copper electroplating was carried out on the surface of sintered NdFeB magnet in an alkaline cyanide-free bath with 1-hydroxyethylidene-1,1-diphosphonic acid(HEDP)as the main complexing agent.The effect of mass concentration of HEDP on the appearance,surface roughness,thickness,adhesion,and corrosion resistance of Cu coating was studied.[Result]The Cu coating electroplated with 100-150 g/L of HEDP was bright with a thickness of about 1.55 μm,low surface roughness,and the best adhesion and corrosion resistance.[Conclusion]Appropriate HEDP concentration in bath is favorable for forming a Cu coating with good comprehensive performance.