Insight of the role of cooling method and soil environment on the corrosion behavior of Mg–2Nd alloys

Abstract

Understanding the corrosion behavior of Mg alloys in the soil environments is crucial to preventing catastrophic accidents in their facilities due to the soil corrosion. The Mg–2Nd alloys were exposed to the soil after cooling in different ways under the same heat treatment conditions. The corrosion mechanisms of Mg–2Nd alloy in the soil are mainly affected by corrosion micro-batteries and macro-batteries. The more precipitates, the more severe micro-galvanic corrosion are formed. Meanwhile, the corrosion product films are damaged by micro-galvanic corrosion, which have a serious impact on the differential concentration of oxygen and differential infiltration of rainwater corrosion. The Mg–2Nd alloy buried in the soil with high water content and low oxygen permeability in corrosive macro-batteries will be corroded into anodes, thereby accelerating the corrosion rate of Mg–2Nd alloy in this part. Furthermore, the formation of corrosion product MgCO3 reduces the electrochemical activity of the sample surface, thereby reducing the corrosion rate of Mg–2Nd alloy in the soil. Therefore, the Mg–2Nd alloy after water-cooling has the best corrosion behavior in the soil environment.

Keywords

• Mg–2Nd alloy
• Micro-galvanic corrosion
• Differential concentration of oxygen
• Differential infiltration of rainwater
• Corrosion behavior