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R. Supplit, T. Koch, U. Schubert:
"Evaluation of the anti-corrosive effect of acid pickling and sol-gel coating on magnesium AZ31 alloy";
Corrosion Science, 49 (2007), 3015 - 3023.

The effect of different acid pre-treatment procedures on the corrosion of magnesium AZ31 alloy was compared by measuring the amount of hydrogen gas formed when the surface was in contact with aqueous 5% sodium chloride solution. A 4-7 μm thick sol-gel coating prepared by phosphoric acid catalyzed sol-gel processing of a methyltriethoxysilane/tetraethoxysilane mixture was applied to the differently pre-treated magnesium surfaces. The corrosion rate of the alloy decreased by a factor of up to 60 by combination of acid pickling and sol-gel coating. The addition of triethylphosphate or 1,2,4-triazole as corrosion inhibitors led to further improvements. Composition and texture of the films was investigated by scanning electron microscopy and energy dispersive X-ray analysis.

Magnesium; SEM; Oxide coatings; Passive films

http://dx.doi.org/10.1016/j.corsci.2007.02.006