Development Of High-power Micro-arc Oxidation Power And Surface Treatment Process Of Aluminum Alloy

As a new method of surface treatment, Microarc oxidation (MAO) is developed from anodic oxidation. The oxide ceramic coatings were formed in-situ on aluminium%magnesium、magnesium and alloys material using microarc oxidation. The coatings prepared by this method have excellent performances in terms of friction, corrosion resistance, thermal shock resistance and insulation performance. Therefore, the micro-arc oxidation technology is widely used in aviation, aerospace, automotive, electronics, medical and other fields. At present, there is no academic model that can explain various experiment phenomenons. Research on mechanism should be conducted further and perfectly. In order to solve these problems, the paper is going to complete the following tasks:(1) In this dissertation, an instrument was firstly designed and made to fabricate MAO coatings on Surface on Aluminum sample. The device contains:micro-arc oxidation power, electrolysis cell, radiator, agitator. The design of micro-arc oxidation power is divided into three main parts:firstly, the main circuit (rectifier, voltage regulator module, chopper module, etc.) of micro-arc oxidation power’s design was investigated. Secondly, the control circuit of the power supply was investigated, it’s effects are to achieve the size of the power, duty cycle of the positive pulse, power frequency, the polarity to be controlled; finally, the design of the power supply protection circuit was investigated, it contains protection of thyristor and the protection of the IGBT module.(2) The effect of the instrumented parameters on surface properties of the films, including voltage magnitude, power frequency, duty cycle, treatment time, is investigated in details. The coating thickness、hardness of compact layer and surface morphology were regarded as indicator to evaluate the performance of ceramic coatings formed in MAO process. Five groups of experiments were processed. The properties of ceramic coatings formed in experiments were studied. The microstructure. Phase composition and elements of coating were analyzed by method of SEM and XRD. The performances of coating were also studied. The better electrical parameters of MAO were summed up.