Effect of Sodium Phosphate Concentration on Corrosion Behavior of the Coatings Produced by Plasma Electrolytic Oxidation (PEO) on AZ31B Mg Alloy in Body Simulative Fluid

Chaharmahali, Razieh; Shadabi, Mozhgan; Babaei, Kazem; Gashti, Seyed Omid; Fattah-alhosseini, Arash

Effect of Sodium Phosphate Concentration on Corrosion Behavior of the Coatings Produced by Plasma Electrolytic Oxidation (PEO) on AZ31B Mg Alloy in Body Simulative Fluid

Document Type : Original Article

Authors

Razieh Chaharmahali

Mozhgan Shadabi

Kazem Babaei

Seyed Omid Gashti

Arash Fattah-alhosseini

Department of Materials Engineering, Bu-Ali Sina University, Hamedan, 65178-38695, Iran

Abstract

In this research, plasma electrolytic oxidation (PEO) coating on AZ31B magnesium alloy having various concentrations has been studied in order to amend the surface corrosion resistance. To do this, phosphate electrolyte with different concentrations of 4, 8 and 10 g/l is investigated. Electrochemical impedance spectroscopy and potentiodynamic polarization tests on an uncoated base alloy and a coated one are studied in a body simulant physiological solution (Ringer's solution). Surface morphology and microstructural surveys were done by X-ray diffraction (XRD) pattern and scanning electron microscopy (SEM). The obtained results of this study displayed that rising the sodium phosphate concentration led to an increase in coating thickness and decreases its porosity. The highest corrosion resistance arose from the lowest corrosion current density (0.45×10-6 A/cm2) of the formed coating in electrolyte containing 10 g/l sodium phosphate.

Keywords

Plasma electrolytic oxidation

AZ31B magnesium alloy

Electrochemical Impedance Spectroscopy

Potentiodynamic polarization