Effect Of Nanoparticle Additives On The Microstructure And Corrosion Properties Of Plasma Electrolytic Oxidation Coatings On Magnesium Alloys: A Review

In recent years, nanoparticles are increasingly used in scientific research and have attracted the attention of many scholars. In this paper, ceramic coatings were prepared on the surface of magnesium and its alloys using the plasma electrolytic oxidation (PEO) technique. We investigated different nanoparticles added to the electrolyte and explored the mechanism of nanoparticle effects on the formation and protection mechanism, morphology and structure, thickness and roughness, and electrochemical corrosion behavior of the coatings. The results show that the coating morphology changes significantly and the surface is more uniform and dense due to the addition of nanoparticles in the electrolyte. The addition of nanoparticles increases the thickness of the coating to some extent, but as its addition to the electrolyte increases, the coating thickness decreases. Since the prepared coatings inevitably produce micropores and microcracks, which may have an impact on the corrosion resistance of the coatings, how to improve the corrosion resistance of the coatings has become a common concern. Nanoparticles can participate in the growth of the coating and will enter the micropores under discharge conditions. On the one hand, they can play a role in closing the porous layer, and on the other hand, they will form some special structures on the surface, thus improving the corrosion resistance of the coating. Finally, we outlook the problems and challenges of the PEO technique in practical applications.