The Effect of Malonic Acid and Succinic Acid on the Corrosion Behavior of Mg-5Zn in (Nh4)3PO4 and NaF

Abstract

While having excellent biocompatibility and biodegradability properties, magnesium alloys have been widely known to exhibit low corrosion resistance, especially in an acidic environment. The partially protective layer of Mg(OH)2 plays an important role in the corrosion behavior of magnesium, while a phosphate and fluoride conversion film enhances the corrosion resistance of magnesium alloy. The comparative study of electrochemical corrosion behaviour of Mg-5Zn with different media was performed in 1% (NH4)3PO4 and 1% NaF. The effect of malonic and succinic acid on the corrosion behaviour of Mg-5Zn was also analyzed. The back scattering electron mode of scanning electron microscopy was used to characterize the microstructure of Mg-5Zn alloys. Electrochemical impedance spectroscopy (EIS) and the potentiodynamic polarization curve were employed to study the electrochemical corrosion behaviour of Mg-5Zn. It was found that the presence of malonic and succinic acid decreases film resistance and enhances the electron transfer of Mg-5Zn in 1% (NH4)3PO4and 1% NaF. A higher Mg-5Zn dissolution rate was observed in a binary mixture of 1% malonic acid and 1% succinic acid with 1% (NH4)3PO4 and 1% NaF in comparison with Mg-5Zn in 1% (NH4)3PO4 and 1% NaF.

Keywords

• corrosion
• electrochemical impedance spectroscopy
• mg-5zn
• potentiodynamic polarization