Influence of Electrolyte Composition (Simulated Body Fluid vs. Dulbecco’s Modified Eagle’s Medium), Temperature, and Solution Flow on the Biocorrosion Behavior of Commercially Pure Mg

Magnesium (Mg) and Mg-based alloys are promising materials for biodegradable implant applications. Electrolyte composition, temperature, and dynamic conditions can differ strongly for in vitro and in vivo environments. In the present work, a direct comparison of two established electrolyte systems—simulated body fluid (SBF) and the cell culture medium Dulbecco’s Modified Eagle’s Medium (DMEM)—for electrochemical measurements is shown. In addition, the influence of temperature and solution flow for DMEM on the corrosion behavior of commercially pure (cp)-Mg is investigated. Electrochemical impedance spectroscopy and potentiodynamic polarization experiments indicate drastically lower corrosion rates in DMEM than in SBF. For both electrolytes the formation of Ca-phosphate-rich layers is observed, which mainly differ in their structure/morphology. Temperature increase (from room temperature to 37°C) only shows a minor influence on the corrosion behavior of Mg. Solution flow, however, strongly affects corrosion resistance of cp-Mg. With increasing flow rates, the corrosion resistance is decreasing. The main cause for the different corrosion behavior seems to be the surface pH that can only rise significantly in static DMEM and thus leads to denser corrosion layers.