Effect of ethanolamine on the anticorrosive properties of phosphate coating prepared on AZ91D magnesium alloy

In this paper,the effect of the concentration of ethanolamine additive on the anticorrosive properties of phosphate coating,which was prepared on AZ91D magnesium alloy,was investigated by potentiodynamic polarization curves and electrochemical impedance spectroscopy(EIS)techniques.The results showed that,(1)Ethanolamine(MEA)additive could improve the anticorrosive properties of phosphate coating.The corrosion resistance of phosphate coating is improved by 10 times that of the AZ91D magnesium alloy in 3.5wt% NaCl solution when the concentration of ethanolamine additive was 1.2g/L.(2) When the concentration of ethanolamine additive ranged from 0.4-1.2g/L,the anticorrosive properties of phosphate coating was in direct proportion to the concentration of ethanolamine additive;however,with the further increase in the concentration of ethanolamine additive,the anticorrosive properties of phosphate coating began to decrease.The phosphate coating with good anticorrosive properties could be obtained when the concentration of ethanolamine additive is between 0.8 and 1.6g/L.