Synergistic Action of Sulfate and Chloride Anions on the Corrosion Behavior of AZ31B Magnesium Alloy

摘要

Magnesium and its alloys have a great potential for lightweight structure applications, because magnesium has lower density (～1.7 g.cm~(-3)) compared to aluminum (2.7 g.cm~(-3)) and iron (～7.9 g.cm~(-3)). Magnesium alloys also exhibit high strength-to-weight ratios. Their use enables the weight reduction of automotive and aerospace vehicles for more energy consumption efficient. However, magnesium alloys have a limitation for practical application, namely the high chemical activity, porous corrosion product and high corrosion rate. In addition, due to the rapid industrialization in some developing countries, air pollution (like PM2.5) has become a hot topic. Most of air pollutants contain ions like SO_4~(2-), NO~(3-) and NH~(4+), which have high solubility. The corrosion behavior of magnesium in chloride-containing environment is also worth studying because CI~- is the most common aggressive corrosion species. In contrast, sulfate ions in chloride-containing solutions can inhibit hydrogen evolution. It is thus of great interest to understand the corrosion behavior of magnesium alloys in solution containing different anions, which provides a basis for designing the effective conversion coating process.