SCRATCH ADHESION EVALUATION OF ELECTROLESS NICKEL PLATING ON Mg AND Mg ALLOYS

Abstract

Magnesium ( Mg ) and its alloys are being used as structural components in industry because of their high strength-to-weight ratio and relatively high stiffness. A shortcoming of Mg based alloys is their poor corrosion and wear resistance. Therefore, coatings or surface treatment are needed for protection purpose. This paper reports our work on electroless plating of Ni - P on Mg alloys. Pure Mg , AZ31 and AZ91 Mg alloys were used as the substrates to investigate friction and adhesion properties of the electroless Ni - P coatings. The maximum friction coefficient (~0.3) was found on the electroless nickel coating of pure Mg substrate. The adhesion strengths of the coatings on AZ31 and AZ91 Mg alloys are higher than that on pure Mg . The critical load (a measure of adhesion strength) of AZ31 reached 13.1 N .