Localized electrochemical study of corrosion inhibition in microdefects on coated AZ31 magnesium alloy

In the present work corrosion inhibition in microdefects of protective coatings on magnesium alloy was studied by SVET (scanning vibrating electrode technique) and SIET (scanning ion-selective electrode technique) in 0.05 M NaCl. Mg2+- and pH-selective microelectrodes were developed to be used by SIET. The microelectrodes were characterized from the standpoint of properties important for corrosion applications, aiming at the reliable functioning during measurements. The combination of SVET and SIET demonstrated to be a useful approach to investigate the inhibition of corrosion processes in microdefects on coated AZ31. In this paper the corrosion inhibiting properties of 1,2,4,-triazole, F− and Ce3+ on AZ31 alloy were analyzed. According to the results, 1,2,4-triazole in concentration of 0.01 M showed the highest inhibition efficiency among the studied inhibitors and was able to prevent the increase of pH in the corroding defects, by keeping the corrosion activity on a very low level during the tested immersion period.