Chemical conversion treatment by rare earth metal salt solution was considered as an alternative to chromium chemical conversion treatment to improve the corrosion resistance of magnesium alloys. In this study, cerium...Chemical conversion treatment by rare earth metal salt solution was considered as an alternative to chromium chemical conversion treatment to improve the corrosion resistance of magnesium alloys. In this study, cerium conversion coatings formed on AZ31 magnesium alloy were characterized and the formation mechanism was discussed. X-ray photoelectron spectroscopy （XPS） analysis showed that cerium conversion coating consisted of cerium hydroxides/oxides, in which both tetravalent cerium Ce（Ⅳ） and trivalent cerium Ce（Ⅲ） species co-existed. Cerium conversion coating was a two-layer structure. Atomic force microscopy （AFM） images revealed that the morphology of the inside layer was different from that of the outside one, which was responsible for the inherent adhesive weakness of the coating. Corrosion potential （Ecorr） measurements indicated that poor adhesion limited the improvement of the corrosion resistance of the coating. During the treating process, the increased pH value of the cerium salt solution led to the precipitation of cerium hydroxides/oxides. The formation kinetics of the coating followed a parabolic curve.展开更多
Corrosion potential measurement,electrochemical impedance spectroscopy(EIS) and scanning electronic microscopy(SEM) were employed to study the inhibition of hexamethylenetetramine(HA) on corrosion of AZ31 magnesium al...Corrosion potential measurement,electrochemical impedance spectroscopy(EIS) and scanning electronic microscopy(SEM) were employed to study the inhibition of hexamethylenetetramine(HA) on corrosion of AZ31 magnesium alloy in simulated coolant.HA exhibits good inhibition after the inducement period through strong adsorption on AZ31 magnesium alloy surface.The addition of HA improves the corrosion resistance of the alloy and affects the corrosion potential little.HA is a mixed-type inhibitor that inhibits both anodic and cathodic reactions of AZ31 magnesium alloy in simulated coolant.展开更多
基金National Outstanding Youth Science Foundation of China (NSFC50725413)the National Natural Science Foundation of China (NSFC20603049)Natural Science Foundation Project of CQ (CSTC2007BB4154)
文摘Chemical conversion treatment by rare earth metal salt solution was considered as an alternative to chromium chemical conversion treatment to improve the corrosion resistance of magnesium alloys. In this study, cerium conversion coatings formed on AZ31 magnesium alloy were characterized and the formation mechanism was discussed. X-ray photoelectron spectroscopy （XPS） analysis showed that cerium conversion coating consisted of cerium hydroxides/oxides, in which both tetravalent cerium Ce（Ⅳ） and trivalent cerium Ce（Ⅲ） species co-existed. Cerium conversion coating was a two-layer structure. Atomic force microscopy （AFM） images revealed that the morphology of the inside layer was different from that of the outside one, which was responsible for the inherent adhesive weakness of the coating. Corrosion potential （Ecorr） measurements indicated that poor adhesion limited the improvement of the corrosion resistance of the coating. During the treating process, the increased pH value of the cerium salt solution led to the precipitation of cerium hydroxides/oxides. The formation kinetics of the coating followed a parabolic curve.
文摘Corrosion potential measurement,electrochemical impedance spectroscopy(EIS) and scanning electronic microscopy(SEM) were employed to study the inhibition of hexamethylenetetramine(HA) on corrosion of AZ31 magnesium alloy in simulated coolant.HA exhibits good inhibition after the inducement period through strong adsorption on AZ31 magnesium alloy surface.The addition of HA improves the corrosion resistance of the alloy and affects the corrosion potential little.HA is a mixed-type inhibitor that inhibits both anodic and cathodic reactions of AZ31 magnesium alloy in simulated coolant.
