Experimental Apparent Stern-Geary Coefficients for AZ31B Mg Alloy in Physiological Body Fluids for Accurate Corrosion Rate Determination

The corrosion behavior of AZ31B Mg alloy exposed to Ringer's, phosphate-buffered saline (PBS), Hank's, and simulated body fluid (SBF) solutions for 4 days was investigated using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, weight loss, and surface characterization. Changes in corrosion rates with immersion time determined by weight loss measurements were compared with EIS data to determine the possibility of obtaining quantitative electrochemical information. In addition, changes in the protective properties of the corrosion product layer calculated from the EIS parameters were evaluated as a function of their surface chemical composition as determined by X-ray photoelectron spectroscopy (XPS) and visual observations of the corroded specimen's surface. Apparent Stern-Geary coefficients for the AZ31B Mg alloy in each test solution were calculated using the relationship between i(corr) from weight loss measurements and the EIS data (both R-p and R-t). This provided experimental reference B ' values that may be used as a useful tool in independent investigations to improve the accuracy of corrosion rates of AZ31B Mg alloy in simulated body solutions.

Automated summary

The corrosion behavior of AZ31B Mg alloy exposed to different solutions was investigated using various techniques including EIS, weight loss measurements, and surface characterization. The study compared corrosion rates determined by weight loss with EIS data and evaluated changes in the protective properties of the corrosion product layer. The Stern-Geary coefficients were calculated for each solution to provide reference B' values for future studies on improving the accuracy of corrosion rates in simulated body solutions.