The corrosion behaviour of MAO coated AZ80 magnesium alloy with surface indentation of different sizes

Abstract

In order to investigate the effect of surface indentation size on the corrosion behaviour of MAO coated AZ80 magnesium alloy, the laser confocal microscope, scanning electron microscope, X-ray diffractometer and electrochemical test were carried out to study the corrosion process of MAO coated AZ80 and the coatings damaged with different impact heights. The results display that when MAO coating was damaged with the impact height of 400 mm, the corrosion current density of the specimen increased to 8.0 × 10−1 μA/cm2 from 3.2 × 10−1 μA/cm2 for MAO without indentation. After immersion for 72 h, the corrosion resistance of the damaged specimens decreased sharply because of the defects on the surface. Moreover, the corrosion mechanism for the coatings with different indentation sizes was clarified.