Effect of ZrO2 nanopaticle content on corrosion resistance of micro-arc oxidation coating on AZ91D magnesium alloy

Abstract

In order to improve the corrosion resistance of AZ91D magnesium alloy, micro-arc oxidation coatings with different ZrO2 nanoparticle contents were prepared by unipolar pulse power supply, and the effect of nano ZrO2 particles on the corrosion resistance of AZ91D magnesium alloy micro-arc oxidation coatings was studied. Scanning electron microscope was used to observe the surface and cross-sectional morphology of the composite films, meanwhile, X-ray diffractometer was used to analyze the phase composition of films with different contents of ZrO2 nanoparticles. The prepared samples were then tested for electrochemical corrosion performance. The results show that when the content of 1 g/L ZrO2 particles is added to the electrolyte, the nano ZrO2 particles can penetrate into the micro-arc oxidation film layer to close the original defects such as micropores and microcracks, and the surface quality of the film layer is good. When the content of ZrO2 particles in the coating layer is increased from 2 g/L to 3 g/L, the crack formation of the coating layer is obviously enhanced, which makes it easier for the corrosive medium to enter the coating layer, so that corrosion is more likely to occur, and the corrosion resistance performance decreases. Therefore, when the content of nano-ZrO2 particles added to the electrolyte is in the range of 1-3 g/L, the corrosion resistance of the micro-arc oxidation film layer with 1 g/L ZrO2 nanoparticles is the best.

Keywords

• micro-arc oxidation
• zro2 nanoparticle
• az91d mg alloy
• xrd spectrum
• corrosion resistance
• polarization curve
• ac impedence