Corrosion behaviour of AZ31 magnesium alloy in saline containing glucose at different concentrations

Abstract

AZ31 magnesium alloy was subjected to corrosion tests in a 0.9% NaCl containing 0 to 5 g/L D-glucose at 37°C. Potentiodynamic measurements were performed in corrosive environments with natural pH and with the pH set to 7.4. The results show that glucose in the range of 0.1 to 5 g/L led to a deterioration of the corrosion resistance of AZ31 alloy in 0.9% NaCl at an initial pH of 7.4. If the corrosive environment did not have a set pH, then a slightly different behavior was observed. Addition of 0.1 g/L glucose to 0.9% NaCl resulted in inhibition of corrosion, while higher concentrations accelerated corrosion. The corrosion aggravation was related to the oxidation of glucose to gluconic acid, which together with chlorides degraded the Mg(OH)2 layer on the AZ31 alloy surface. Surface analysis revealed that the corroded AZ31 alloy was covered with fine crystals in the absence of glucose.