The Study On Micro-arc Oxidation Ceramic Layer Of Magnesium Alloy

In this article, the effects of electrolyte and electrical parameters on the thickness, compactness and surface roughness of the magnesium alloy Micro-arc Oxidation ceramic layer are studied by the MAO equipment designed by ourself. The corrosion resistance of magnesium alloy Micro-arc Oxidation ceramic layer and anodic oxidation layer is compared by neutral NaCl salt hare corrosion test and electrochemical analysis test. The results show that the corrosion resistance of Micro-arc Oxidation ceramic layer is better than anodic oxidation layer' s, and the corrosion current of the latter is higher than the former' s by 2 to 3 order of magnitudes. The micro-structure of the ceramic layer is studied by metallographic microscope, scanning electron microscope (SEM), and X-ray diffractometer. The results show that the ceramic layer is formed by minute cone-like grain under the condition of micro-arc discharge. Each grain has a pore in its center. With the thickness increasing, the cone-like grain and the pore of the ceramic layer grow larger. On the contrary, the density of the grain becomes decrease. The combination between ceramic layer and matrix is metallurgical binding. The ceramic layer is mainly composed of MgO and a bit of MgAl2O4 and Mg2SiO4.