Study Of Electroplating On Magnesium Alloy

Magnesium alloys are increasingly being utilized in fields such as automotive, power tools and computer industries on account of their excellent properties including low density,high strength-to-weight ratio, excellent imensional stability, high impact resistance and good thermal as well as electrical conductivity. However, poor corrosion resistance of magnesium restricts its engineering application.Enhancing the corrosion resistance by appropriate surface treatment is significant.In surface treatment of magnesium alloy, the most simple and effective way is to plat another metal or alloy by electrochemical method on magnesium alloy, which is plated. To plat on magnesium alloy, it not only can obtain high corrosion resistance of the coating, but also can improve coating layer according to different requirements. It is an irreplaceable plating surface treatment, for improving the surface conductivity, thermal conductivity, weldability, wear resistance.In this paper, the nature of magnesium alloys, applications, corrosion and protection was reviewed. Zinc immersion is studied. Find the most suitable way that is applyed to pre-dip zinc on magnesium alloy. On this basis, the time, temperature and ultrasonic technology on zinc immersion have been investigated. The theory of zinc immersion on magnesium alloy is elaborated. The effect of current and ultrasonic on electroplating of Cu and Zn on magnesium alloy have been studied by SEM, polarization curve, adhesion strength test and soak in NaCl. The research results of the experiments show that: It get good Zn coating by 1.5 A/dm~2～2.5 A/dm~2; it get good Cu coating by 1.0 A/dm~2～2.0 A/dm~2. Magnesium alloy is plating by there current wave forms (smoothed, half-wave rectified and full-wave rectified DC). The coating layer has the best performance with smoothed DC. The metal deposit on AZ91D with ultrasonic has the following advantages: uniform and smooth deposit grains, strong adhesion and good corrosion resistance. It is a new technology to plat on magnesium alloy with ultrasonic. It does not need to change the composition.