Carboxylates as green corrosion inhibitors of magnesium alloy for biomedical application

The efficiency of the green inhibitors (sodium salts of fumarate, glycolate and gluconate) in suppressing corrosion of the structural MA8 magnesium alloy (Mg Mn Ce) and the biomedical Mg 0.8Ca alloy was studied using the hydrogen evolution measurements, mass loss test, EIS, PDP, SVET/SIET. The analysis of the morphology, chemical composition, and growth kinetic of corrosion films formed in 0.9 wt% NaCl solution with and without corrosion inhibitors was carried out. The most compact surface film with the smallest thickness was formed in a saline solution with sodium fumarate. The Mg alloy samples exhibited the highest polarization resistance, the lowest localized electrochemical activity, and the lowest corrosion rate in saline with the addition of sodium fumarate and sodium glycolate. The efficiency of the applied inhibitors was up to 81 %. The model of the corrosion mechanism based on the sorption of molecules of organic inhibitors is proposed. The results show the high compatibility of the used inhibitors with the calcium-phosphate PEO-matrix, indicating the possibility of forming a self-healing coating by means of these active substances.