Features of the corrosion processes development at the magnesium alloys surface

• Compared corrosion stability of Mg alloys was studied by the SVP method.
• The reasons, which provide the corrosion behavior of Mg alloys have been revealed.
• Results obtained by the independent methods correlated with SVP data.
• PEO-coatings significantly diminish corrosion activity of the various Mg alloys.
• SPTFE treatment of PEO-layers sharply decreases values of the corrosion rate.

A greater corrosion stability of the MA8 (MgMnСе) alloy as compared to that of VMD10 (MgZnZrY) magnesium alloy in the chloride-containing solution has been demonstrated using the scanning vibrating probe method (SVP) as well as the methods of optical microscopy, gravimetry, and volumetry. It has been established that the crucial factor of the corrosion activity of the samples under study consists in the occurrence of microgalvanic couples at the sample surface. The corrosion rate of the samples with coatings formed by the plasma electrolytic oxidation (PEO) method and composite polymer-containing coatings at the surface of various magnesium alloys has been measured. The best anticorrosion properties have been manifested by composite polymer-containing coatings. The corrosion rate (PН) values for both types of the magnesium alloys (MA8 and VMD10) were about 0 mm per year upon exposure of the samples to the 3% NaCl solution for 7 days.