Design Of Micro-arc Oxidation Pulse Power And Its Auxiliary Electromagnetic Field And Experimental Study

Micro-arc oxidation(MAO) is a surface treatment technology which could generatea ceramic membrane on the surface of the valve metals, such as aluminum, magnesium,titanium and its alloy. Relative to the anodic oxidation film, MAO’s ceramic coating hasa series of advantages like firmly attaching to the substrate and resisting corrosion,abrasion, high temperature and insulation well. Power supply is the key equipment inMAO, this research is aim to solve the problem that power lacks of control mode andmake the conditions during micro-arc oxidation process varied, to study and explore theinfluence of different current waveform control methods and electromagnetic field tomicro-arc oxidation process, providing technical support to further improve theperformance of coating and the application of micro-arc oxidation technology.In view of the new requirements, designed a bipolar micro-arc oxidation powersupply and electromagnetic field generator. The power supply can not only adjustmentthe positive and negative parameter flexibly, but also provide different current controlmodes, just like control current instantaneous value both positive and negative, controlcurrent average value both positive and negative, control the combination of currentinstantaneous value and average value in different electrodes.Studied the influence of different current waveform control methods to the MAO’sprocess and the film performance, the voltage and current waveform changes observedin the experiments were analyzed. Effect of electromagnetic on the process of MAO andproperties of coating were studied. Use electrochemical workstation to appraise thecorrosion resistance of the film. By means of metallographic microscope and SEM toobserve the surface and section morphology of the ceramic layer. With the help of EDSand XRD to detect the coating element and phase composition.The results show that in a short time of MAO, negative waveform control effectson film performance. In the long time of MAO, different current waveformcontrol modes has significant effect on the film thickness and hardness, the thickest andmost hard film was obtained when control the instantaneous value of positive andthe average value of negative. According to the experimental results, analysis ofeffect mechanism of the positive and negative pulse, explained the effects ofdifferent current waveform control methods on MAO from the angle of pulse energy.The introduction of electromagnetic can accelerate the film growth rate, improve thefilm properties, and change the content of the coating elements and phase composition.