Improvement of corrosion resistance of DC PEO coating on AZ80 magnesium alloy through two-step PEO process combined with laser cleaning

This paper deals with the influence of a two-step PEO process combined with laser cleaning method used on the AZ80 magnesium alloy. The main aim is to improve the corrosion behavior of the porous coating in an aggressive chloride environment. Additionally, formation of secondary PEO coating was optimized in terms of the PEO preparation time. Corrosion characteristics of prepared surfaces were evaluated by electrochemical impedance spectroscopy (EIS) measurements during 168 h of exposure and potentiodynamic polarization (PDP) tests at the laboratory temperature in 0.1 M NaCl solution. Morphology and thickness of PEO coatings was analyzed by scanning electron microscopy (SEM). Laser cleaning as a precursor to optimized secondary PEO coating improved barrier effect as well as the corrosion resistance of the AZ80 alloy due to increased protection in an aggressive environment. • Plasma electrolytical oxidation (PEO) process was applied in two steps in combination with laser cleaning method. • Electrochemical characteristics were obtained by EIS measurements. • Laser cleaning method combined with two step PEO process had a beneficial effect on mid-term corrosion resistance of the PEO coating optimized for 150 s. • Corrosion mechanisms of PEO coatings in combination with the laser cleaning method were compared and discussed.