Mg Corrosion—Recent Progress

Abstract

Recent progress is reviewed. Recent developments include: (i) accumulation of evidence that electrochemical measurements of the Mg corrosion rate often do not agree with the steady state Mg corrosion rate as measured by weight loss; (ii) low Fe tolerance limits are caused by heat treatment of nominally high-purity Mg and the presence of Si, (iii) the intrinsic Mg corrosion rate is 0.3 mm/y in a chloride solution as measured by weight loss, (iv) there are many Mg alloys with corrosion rates between 0.3 and 1.0 mm/y, (v) there are few Mg alloys with corrosion rates less than 0.3 mm/y, (vi) experimental evidence contradicts the enhanced catalytic activity mechanism of Mg corrosion, (vii) experiments support the uni-positive Mg+ mechanism, (viii) new compelling experimental evidence supporting the uni-positive Mg+ corrosion mechanism has been provided by electrochemical impedance spectroscopy (EIS), and (ix) the uni-positive Mg+ corrosion mechanism provides new insights for understanding the performance of Mg-air batteries and for the development of better Mg anodes.

Keywords

• Mg corrosion
• anodic hydrogen
• intrinsic Mg corrosion rate
• uni-positive Mg⁺ corrosion mechanism
• enhanced catalytic Mg corrosion mechanism
• apparent Mg valence