The Influence Of Electrical Parameters On The Energy Consumption And Properties Of Ceramic Coating Fabricated By Micro Arc Oxidation

Owning outstanding physical and mechanical properties, as well as the abundant storageon earth, aluminum alloys are widely applied to the industry fields of electroniccommunication, aerospace technology, automobile manufacturing and so on. Nevertheless,due to the problem of poor corrosion resistance, further application of aluminum alloys islimited. Therefore, it is essential for aluminum alloys to improve their surface properties bysurface treatment.Micro arc oxidation(MAO) is a surface treating method based from anodizing. Itcombines multiple mechanisms of chemistry, electrochemistry, physical chemistry and plasmachemistry, aiming at forming a metallurgical bonding ceramic coating on the in situ surface ofthe valve metal substrate. Compared with other treating methods, micro arc oxidation hassome outstanding advantages, such as the electrolyte utilized causes little environmentalpollution, the whole process is simple, the equipment operated easily and so on. Concurrently,the coatings prepared by this method can exhibit some advantages like uniform color, highadhesion as well as excellent corrosion resistance. With the deepening of research in recentyears, micro arc oxidation has been considerable developing. However, MAO itself stillremains some shortcomings unresolved, and among them the whole exhaustive processbecomes a direct constraint to a wider industrial application.In this paper, the effects of discharge waveform relevant parameters for the consumptionof micro arc oxidation process and the performance of ceramic coating are studied, and theinfluence of each parameter is analyzed systematically. In current experimental conditions, thewaveform is optimized, and through the following orthogonal experiment, the optimal processparameters to the preparation of6061micro arc oxidation ceramic coatings are determined.The coating is uniform, smooth and dense, and the energy consumption of the whole processis only4.0kw·h/(m2·μm).SEM, EDS, XRD and other means of detection were utilized to characterize the micromorphology, composition and structure of MAO coatings under the optimal parameters.Concurrently, electrochemical workstation, drip test, salt spray test were used to detect thecorrosion performance of the coatings. Few obvious cracks or loose micro areas were observed on the surface of the light gray ceramic coating, whose thickness was relativelyuniform, about6.3μm, and a small amount of defects formed during the growing process aswell as some pits left by the collapse of bubble inclusions reserves in the internal coating. Themain phase composition of the coating was γ-Al2O3, and a small amount of α-Al2O3existed,too. The corrosion current density of the coating was about5.0×10-9A/cm2, representing anapproximate3magnitude increase compared to the substrate’s, and its drip-resistant time wasprolonged about80times than the substrate, indicating the corrosion resistance of the filmwas significantly improved over the substrate.