Electron Excitation Effect of Pure Mg Surface on initial Corrosion Phenomenon

Magnesium (Mg) has the lowest negative standard electrode potential (-2.363V) among industrial metals. This means that corrosion phenomena easily occur when Mg specimens contact with other metals because a galvanic cell is formed at the interface between two materials due to their large potential difference. The conventional method to improve corrosion resistance of Mg alloys is anodic oxide film formation and/or chemical conversion treatment. However, these methods are expensive and chemically treated Mg products are hard to recycle. In this study, a new corrosion protection method by electron excitation to change the surface potential of pure Mg was investigated. The surface potential variation of pure Mg was measured by using Scanning Kelvin Probe Force Microscopy (SKPFM) to determine the anodic/cathodic area at the interface between different phases in the local galvanic cell. The electronically excited area by electron beam irradiation of a Scanning Electron Microscope (SEM) showed a lower surface potential than that of the as-polished original surface. SEM observation results indicated corrosion resistance at the electronically excited area of a pure Mg specimen was improved. This observation is also supported by salt water immersion tests and Atomic Force Microscope (AFM) analysis results as they indicate fewer corrosion products at the electronically excited area