Improving corrosion resistance of AZ31B magnesium alloy via a conversion coating produced by a protic ammonium-phosphate ionic liquid

Magnesium alloys are susceptible to corrosion because of their high reactivity and low electrode potential. The present work introduces a conversion coating using a protic ammonium-phosphate ionic liquid (IL). Initial results on the AZ31B Mg alloy have demonstrated substantially improved corrosion resistance for the IL treatment at 300 °C (IL-300C) compared to the treatment at room temperature. Potentiodynamic polarization analysis of the IL-300C treatedMg surface in a NaCl solution exhibited a strong passivation behavior.No pretreatment is needed and the treated surface morphology is well preserved. Cross-sectional nanostructure examination using transmission electron microscopy and element mapping using energy-dispersive X-ray spectroscopy have revealed the IL-300C conversion coating to be a 70-80 nm thick with a two-layer structure. Further surface chemical analysis using X-ray photoelectron spectroscopy suggested such an IL conversion coating possibly composed of metal oxides, metal phosphates, and carbonaceous compounds.

Duke Scholars

Author Miaofang Chi Thomas Lord Department of Mechanical Engineering and Materia ...