Process And Properties Of Electroless Ni-P Coating On Magnesium Alloy

In this paper, we used electroless-plating Ni-P amorphous coating to improve the surface anti-corrosion performance of magnesium alloy. On the basis of studing the process of electroless plating Ni-P on magnesium alloy,the electroless plating process parameters and coating properties were in-depth study.Electroless plating Ni-P amorphous coating on AZ31 magnesium alloy was studied by the orthogonal test method. After the heat treatment, passivation and other post-treatments of the coating, amorphous coating with high corrosion resistance, high hardness,high conductivity and other good properties on AZ31 magnesium alloy was prepared.The effect of the various process parameters including temperature, stirring frequency, reagent concentration on the electroless plating coating was investigated. After forming the thin-film coating, the effect of process parameters on corrosion resistance, hardness, electrical conductivity, thermal conductivity, coating deposition speed and other properties were studied.The phase structure of the coating was detected by XRD. The SEM and EDS were applied to analysis the surface appearance and the composition of the coating. The electrochemical method and salt spray test was used to analysis the corrosion resistance of the coating. The microhardness of the plating coating was measured. Then we also studied the electrical conductivity, thermal conductivity and other physical properties of the coating.The results show that by using AZ31 magnesium alloy as the base body, the nickel carbonate as the main salt in. electroless bath and the sodium hypophosphite as the reducing agent. The electroless plating Ni-P amorphous coating exhibited excellent corrosion resistance. Both the deposition rate and quality performance of the coating can be achieved at 85℃on the condition of appropriately artificial mixing. The Ni-P coating with smooth and bright appearance, was prepared by the above conditions, the binding between the coating and AZ31 magnesium alloy was also very good.