Abstract: Magnesium alloys with a high strength-to-weight ratio are attractive for automotive applications. Yet they have inferior corrosion properties under the road spray conditions. Micro-arc oxidation (MAO) is an effective surface treatment technology that enables the formation of protective ceramic coatings on Mg alloys. As metallic structures are commonly exposed to mechanical loads and corrosive environment simultaneously, the corrosion fatigue behavior of the metal becomes a key factor determining duration of the structures. In this work, the microstructure, corrosion, and corrosion fatigue properties of bare and MAO coated AZ31B cast Mg alloy were studied using SEM, XRD, electrochemical, and rotating-bending testing techniques. It was shown that the MAO coating provided robust corrosion protection of the alloy. However, under cyclic loading conditions a reduction of corrosion fatigue life of the MAO coated Mg alloy was observed. Application of a polymer top coating can be a promising means to mitigate this issue.
Authors: Xin Pang, Yuna Xue, Bailing Jiang, and Hamid Jahed
Keywords: Magnesium alloy, Corrosion fatigue, Micro-arc oxidation, Electrophoretic coating