Corrosion Behavior of AZ61 Magnesium Alloys in NaCl Solution

摘要

Magnesium alloys are used widely because of its good performance. However, its practical application is restricted by low corrosion resistance. In this study, the effects of corrosion time and NaCl concentration on the corrosion behavior of AZ61 magnesium alloy were investigated from the corrosion morphology and the corrosion rate. These results have displayed that the corrosion rate of AZ61 magnesium alloy decreases with the increasing etching time. Meanwhile, the corrosion rate of AZ61 magnesium alloy increases with the increasing sodium chloride concentration. This is mainly because that the Cl- ion in the solution destroys the protective film on the surface of magnesium alloy and the high Cl- ion concentration accelerates the corrosion rate. Magnesium is the lightest metal of commonly used alloys. It is one of the most abundant metal element in the crust, about 2% of the total weight. There are rich in magnesium resources in China. Magnesium alloys have many advantages, such as good conductivity, thermal conductivity and electromagnetic shielding, good specific strength and stiffness, shock absorbing, dimensional stability and cutting, easy recovery and favorable environmental protection, so the application is increasingly widespread in the automotive, motorcycle and other modes of transport, 3C proudcts, aerospace, weapons industry and other fields. Magnesium alloy as the "21st Century Green Engineering Materials", is one of the lightest metallic structure materials in current industrial applictions[l-4]. However, poor corrosion resistance is one of the main problems and it greatly limits the wide application of magnesium alloy for a long time which made the advantages of magnesium alloys are not fully exploited. In order to find a proper solution to solve the poor corrosion resistance, we must have a full understanding about the corrosion process and the corrosion mechanism of magnesium alloy[5]. So the aim of this work was to investigate the corrosion behaviour and the corrosion mechanism of AZ61 maganisum alloy in the different Cl- concentration of NaCl solution.