A semiempirical model for predicting magnesium alloy biodegradation in simulated body fluids: Influence of electrolyte composition and implant geometry

A semiempirical model was developed to predict the biodegradation behavior of AZ31 magnesium alloy in simulated physiological environments. The corrosion performance of the alloy was evaluated in four solutions-Hank's Balanced Salt Solution (HBSS), Dulbecco's Modified Eagle Medium (DMEM), Kokubo solution, and 0.9 % NaCl-by combining electrochemical techniques, hydrogen evolution measurements via gas chromatography, and mass loss analysis. The results showed a strong dependence of corrosion kinetics and mechanisms on electrolyte composition. Generalized corrosion dominated in HBSS and DMEM due to phosphate layer formation, while localized attack was observed in Kokubo and saline media. Power-law degradation rates, derived from hydrogen evolution data, were incorporated into a finite element model of a fibula plate to predict mechanical property loss over time. The model was also applied to a stannate-based conversion coating (CC60), which delayed degradation and reduced early hydrogen release. This framework enables reliable prediction of in vitro implant performance based on corrosion environment and geometry, offering a practical tool for biodegradable implant design.