On the Corrosion Resistant Mechanism of Electroless Nickel Coating on Hard Aluminium Alloy

Through the analysis of microstructure of the hard aluminium alloy, composition of the electroless nickel plating solution, process of electroless nickel plating on aluminium alloy and properties of the nickel- phosphorus deposits, it was found that thickness and porosity of the deposit of electroless nickel plating on hard aluminium alloy were the key factors affecting the corrosion resistance of the electroless nickel coating. The aluminium alloy substrate state, pretreatment and posttreatment technologies, plating solution composition and parameters of the electroless plating process all can affect the porosity of nickel-phosphorus coating obtained. It is necessary to control correctly all important technical points in the whole process of electroless nickel plating on hard aluminium alloy for obtaining high quality nickel-phosphorus alloy coatings.