Some new aspects of the study of dependence of properties of PEO coatings on the parameters of current in potentiodynamic mode

Abstract The method of plasma electrolytic oxidation (PEO) for modifying surface of magnesium alloys is increasingly being used in many areas of industry and medicine. In this paper, the influence of the parameters of PEO process on the formation of coatings in potentiodynamic modes was investigated. The morphology and corrosion properties of PEO coatings were studied by scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffractometry, and electrochemical techniques. It was shown that in the potentiodynamic mode, properties of coatings can be controlled by the maximum formation current density. The influence of a surface area of treated sample on the PEO process and coatings’ properties was studied. It was shown that an increase in voltage limit increases the formation current density of PEO process, which leads to an increase in the thickness and porosity of the coatings. It was found that the rate of voltage’s change did not affect the change in the formation current densities; however, it significantly affected the thickness of the formed layer. It was established that a large coating’s thickness and a small number of pores are not an indicator of high corrosion resistance, the pores size is more significant. The results of this study allow to adjust various surface properties by modifying coating formation mode.