Study Of Growth Process And Insulated Properties Of Ceramic Coatings Formed By Micro-arc Oxidation On Aluminum Alloys

The growth process and mechanism of ceramic coatings formed by micro-arc oxidation on aluminum alloys were studied by the analysis of the surface and sectional pattern for ceramic coatings. The factors investigated which influenced the ceramic coatings on insulated properties were analyzed consequently, And phase distribution and constituents of ceramic coatings were investigated using X-ray diffractometer.The results indicate that the conductivity and pH value of solution and the energy of power supply are the important factors influencing on insulated properties. The growth rate of ceramic coatings increases while the energy consumed in the solution decreases with the increase in the conductivity of solution, so that the utilization ratio efficiency of energy power supply is improved. The pH value can decide the formation of coatings and influence the rate of formation. The pH value to form coatings ranges from 7.5 to 13 for LY12. But micro-arc oxidation can happen in the solution of pH value exceeded 13 when the insulate coating formed on the aluminum beforehand.The choice and control of electrical parameter play a key role in the growth rate and insulated properties of ceramic coatings. The more energy density acts on the ceramic coatings, the faster growing rate of ceramic coatings is. However the insulated intensity candecrease if the energy density acted on the ceramic coatings exceeds some limit. The key to get compact and insulate ceramic coatings is to control the electrical parameter in different growth stage.