Study Of The Micro-arc Oxidation Treatment On The Aluminum Plate Of The Intelligent Power Device And Its Performance Optimization Mechanism

Under the circumstances of the current shortage of energy, the inverter home appliances have widely applied in daily life because they are energy saving and comfortable, meanwhile they accord with the requirement of sustainable development strategy at home and abroad. Intelligent Power Module(IPM) is the most widely used power converter modules which are the core of the inverter home applieances. The domestic companies also have developed intelligent power module independent with the development of inverter home appliances. Substrate requires bonding properties, insulation and thermal conductivity as the major part of the IPM. The anodic alumina substrates are the most commonly used as substrates for IPM. However, the comprehensive performance of the anodic alumina substrate is not excellent for the IPM. Therefore, the purpose of this work is to improve the comprehensive performance of the substrate of intelligent power module by using the micro-arc oxidation technology.This work generate a micro-arc oxide film by using suitable technological parameters, using universal testing machine, AC withstand voltage tester, comprehensive physical property to measurement system to characterization the adhesion force, insulating property, and thermal performance of the micro-arc oxide film layer. Compared with anodic oxidation film, it turned out that the bonding properties, insulation and thermal conductive performance of micro- arc oxidation film is better than that of anodic oxidation film. Furthermore, using SEM, XRD, EDS and mercury injection apparatus to characterization the section and surface morphology, phase composition, element distribution, pore size distribution, and discussed the relationship between the composition, structure of the micro-arc oxide film and its performance. The result is that:(1) the roughness and hole diameter of micro-arc oxide film have an affect on the bonding properties;(2) the mullite lower the coefficient of thermal conductivity and breakdown voltage of the micro-arc oxide film.In this work, the final process parameters of IPM aluminum substrate(0.5 dm2) are: sodium silicate 15g/L, sodium hydroxide 1.5g/L, EDTA disodium 3g/L, dodecyl benzene sulfonic acid sodium 0.25g/L, current density 4A/dm2, pulse frequency 1000 Hz, pulse dutycycle 45%-15%, time 20 minutes. The adhesion force, insulating property, and thermal performance of the micro-arc oxide film layer are 936 N, 0.32 KV, 19.7W/m·k, which are superior to the anodic alumina substrate of Midea refrigeration equipment co., LTD(523N, 0.28 KV, 5.5W/m·k).According to the requirements of industrial applications, this study successfully prepared a micro-arc oxidation film on 67dm2 aluminum plate under low current density(1A/dm2), with the parameters: sodium silicate 18g/L, sodium hydroxide 1.5g/L, EDTA disodium 3g/L, pulse frequency 500 Hz, pulse dutycycle 50%-50%, time 50 minutes. The plate passed the basic performance test of Midea refrigeration equipment co., LTD.