The effect of NaHCO3 treatment time on the corrosion resistance of commercial magnesium alloys AZ31 and AZ61 in 0.6 M NaCl solution

This paper studies the chemical composition and structure of the conversion coatings formed during immersion on saturated aqueous NaHCO3 solution treatment on the surface of as-received commercial AZ31 and AZ61 magnesium alloys with a view to a better understanding of their protective properties. The great uniformity and the significant increase in the amount of aluminium oxides and hydroxides observed on the surface of the conversion coating of the AZ61 alloy after 10 or 60 min of treatment (about 30% higher Al atomic contents) seems to improve the corrosion resistance.

► Surface chemistry of chemical conversion coatings on magnesium alloys.
► Relation between treatment time and aluminium or carbonate surface enrichment.
► Relation between surface composition and protection properties.