A Study Of Optimization Of Pinhole Defects In Electroless Nickel Plating On AZ40M Magnesium Alloy

AZ40M magnesium alloy has low density,high strength and good rigidity.As an industrial manufacturing material with excellent properties,it has been widely used,especially in the aerospace field.However,due to its poor corrosion resistance,its application is limited.In practical applications,the surface treatment of magnesium alloy can make the substrate isolated from the external environment and prevent the occurrence of corrosion.The AZ40M magnesium alloy chemical plating nickel is in the alkaline solution,the surface of magnesium alloy after chemical nickel plating pinhole phenomenon is common,have important influence on the corrosion resistance,aviation industry,this paper applied the AZ40M magnesium alloy chemical nickel plating process,focuses on the three main factors lead to pinhole occur.I selected for six kinds of PH value(7.0?8.0),five kinds of surfactants(sodium dodecyl sulfate,sodium dodecyl benzene sulfonic acid,Polyethylene glycol 200,NP-9 and dodecyl trimethyl ammonium bromide),and four kinds of mixing method(air agitation,mechanical agitation,parts agitation andultrasonic agitation),AZ40M magnesium alloy was prepared by chemical nickel plating layer.The appearance,thickness,binding force,alternating humid heat,th-ermal cycle,thermal vacuum performance and salt spray resistance of nickel plating layer were tested by GB/T 13913-2008,QJ 481-90,GJB 2502.8-2006 and otherstandard measurement methods.The experimental results were analyzed bymeansof SEM,EDS and electrochemical workstation.Experimental results show that:(1)The presence of pinhole will affect the corrosion resistance of AZ40M magnesium alloy electroless nickel plating layer,accelerate the corrosion ratearound the pinhole,and also affect the aesthetic appearance of parts.(2)A PH value of 7.8,the addition of NP-9 and the use of ultrasonic agitation process parameters help to reduce the AZ40M magnesium alloy electroless nickel plating layer pinhole.The research results of this paper provide reliable process parameters for the preparation of AZ40M magnesium alloy electroless nickel plating layer with no pinhole defect,stable performance and satisfying the surface use requirements of aerospace equipment products,which has important practical significance for reducing production cost waste and improving product quality.