Technology Of Deep Hole Electroplating For High Corrosion Resistance Nickel/Copper/Nickel Coatings On NdFeB

Electroplating nickel technology is very mature,which is widely used for its good decoration,high corrosion resistance,low cost,simple process.At present,some parts made of Nd-Fe-B are irregular in shape and the structure is deep or blind.,the coatings cannot be completely covered during the electroplating process,and some properties of the parts such as the corrosion resistance are reduced.Therefore,it is extremely important to improve the deep plating performance of the plating solution.This paper mainly uses Watt’s plating solution as the base plating solution,By single anode inner hole method,combined with Hull cell experiment,salt spray experiment,electrochemical test,metallographic microscope and scanning electron microscope to study the deep plating performance,dispersion ability and corrosion resistance of the plating solution after adding different additives to the basic plating solution and the micro-morphology of the coating,and the determination of the plating process parameters.Further verification of the performance of the studied plating solution on Nd-Fe-B materials.Cathodic polarization curve measurement and cyclic voltammetry curve measurement were used to study the action mechanism of different additives.The best content of each additive in the formulation of the highly corrosion-resistant deep-hole nickel plating solution:dislocation agent SSO3 4ml/L,leveling agent PS 4ml/L,complexing agent sodium citrate 60g/L,conductive salt ammonium sulfate 15g/L.The optimal plating process parameters were determined by the same experiment:current density 1A/dm~2,p H value 4.5,and temperature 50°C.The deep plating resistance and corrosion resistance of the plating solution on the Nd Fe B material are verified:the deep plating ability is 2-3 times that of the basic plating solution,and the corrosion resistance of the resulting plating layer is close to that of the basic plating solution.The mechanism of action of the displacement agent SSO3 and the leveling agent PS is to directionally adsorb on the surface of the cathode,hinder the reduction deposition of nickel ions,reduce the deposition rate of nickel ions,increase the dispersibility of the plating solution,the nickel ions are finely crystallized,and the coating is smooth and bright.The mechanism of action of the complexing agent sodium citrate is to form complex ions with nickel ions,reduce the reduction rate,and increase the cathode polarization.The action mechanism of the conductive salt ammonium sulfate is to improve the conductivity of the plating solution and promote the dissolution of the anode,expand the current coverage area,reduce the bath voltage,and improve the deep plating ability of the plating solution.