Electroless Nikel Plating Combined With Micro-Arc Oxidation On Magnesium Alloy

Micro-arc oxidation is a new type of surface treating technology on the basic of anode oxidation. It use plasma micro-arc to grow ceramic film on original position of metal surface, which can improve wear resistant,corrosion resistant and insulated character of material. As a kind of excellent surface treating technologies, electroless nickel plating can uniform coatings on complicated castings, which has been gained wide recognition and application in recent years. The paper get composite coatings with better corrosion resistance , wear resistance and cleanliness through electroless nickel plating combined with micro-arc oxidation treatment on magnesium alloy.Electrolyte concentration and experimental time, which affect the oxidation film, were studied preliminary in the paper. And the formative mechanics and growth process of Micro-arc Oxidation film on magnesium alloy were also explored in the paper. On the basis of traditional electroless nickel plating on magnesium alloys, solution compositions and operating conditions were improved. Finally, Performance measurement of Micro-arc Oxidation film and electroless nickel coating was done . The conclusion of the paper is below:1. Thickness of oxidation film was increased along with the multiplication of electrolyte concentration and the experimental time in Na2SiO3.When the electrolyte concentration was added to certain value, there were some islands on magnesium alloy's surface.2. The whole surface of oxidation films in Na2SiO3 distribute many holes that were formed by micro-arc discharge, and the size of these holes was uniformity.3. In the paper, it can be concluded that oxidation film was grown at once on magnesium alloy's surface in electrolyte, and Voltage must be increased in order to keep it's growth. But when voltage reach at a certain critical value, oxidation film would be arcing and melted, spark would be brought. Micro-arc oxidation film was not grown on the whole surface at the same time, but was partly broken down and grown in the course of voltage's increase, Which result in entirely incrassation. In the end, terminal thickness of designate voltage would be reached.4. Electroless nickel plating on micro-arc oxidation film of magnesium alloy, the...