Study On Status Of Different Magnesium Alloy Surface Influence On Properties Of Coating

With the demand for improvement of the performance of communication, Somesurface treatment technology, like electroless nickel plating and copper plating, wereused to change the surface properties. However, in the actual industrial production, wefound that the surface conditions of parts had an influence on rate of finished products.So, we selected five kinds of surface conditions including micro-arc oxidation film,passivation film, sandblasted surface, polished surface and oxidized surface. Then, thecopper plating on different surface had been operated to study the influence of surfacecondition for coating.Firstly, some process and program of pretreatment about electroless nickel werestudied and compared. The pickling process (C2H4O2+H3PO4) was selected and theactivation process (HF384ml/L) was selected. It was studied that relational programhad some impact on morphology, deposition rate, porosity of nickel plating. Accordingto the results, more appropriate programs were selected to carry out in the experiment.Secondly, During copper plating process, the influence of some process parameters,like concentration of copper pyrophosphate, density of electric current, pH, for coatingperformance were studied by Hull cell experiments. Then, the appropriate programswere selected to carry out in the experiment.Finally some comprehensive performances including surface resistance, corrosionresistance, porosity were detected and studied. The morphology and composition werealso analyzed by SEM and EDS. The studies had shown that:①Surface resistance of coating on five different surface between4.7m/mm2~6.0m/mm2. The coating on oxidized surface has the strongest surfaceresistance. It’s6.0m/mm2. Compared with the other four surface conditions, thecoating on oxidized surface has low binding capacity and high porosity because ofoxide on surface.②Coating on micro-arc oxidation film and passivation film has better corrosionresistance. Corrosion resistance of coating on oxidized surface is worst. In5%NaClsolution, all coating began to extensive corrosion after4hour.③Sandblasted surface has the fastest deposition rate and maximum film thicknessbecause of the largest roughness.④Micro hardness of coating on five different surface conditions is198~207HV and has good resistance attack ability.⑤The coating on sandblasted surface has better comprehensive performance bycomprehensive evaluation for some performance.