Phosphate-permanganate conversion coatings on the AZ81 magnesium alloy: SEM, EIS and XPS studies

► The proper electrical equivalent circuit for the AZ81 alloy corrosion is proposed. ► The effect of phosphate-permanganate bath content on corrosion resistance is shown. ► The impact of bath's temperature on corrosion resistance is shown. ► The impact of conversion's time on corrosion resistance is shown.