Zone coulometry and ion-release analysis of degradable magnesium alloys

Zone coulometry and determination of ion release of an electrolyte from anodic polarization measurements are the established calculation modes for the electrochemical behavior of dental and biomedical alloys. The aim of the study was to compare the electrochemical corrosion behavior of six different experimental magnesium alloys without manganese using artificial plasma (AP) and in phosphate-buffered saline (PBS⁻) as simulated body fluids through anodic polarization measurements. In addition, determination of the magnesium release of the electrolytes was performed using inductively coupled plasma optical emission spectrometry and zone coulometry. Six specimens were prepared from each alloy. Anodic polarization measurements ranging from –150 mV ~E_corrto –1200 mV were performed with both of the electrolytes. From each measurement, corrosion current density, the breakdown or pitting potential and its corresponding current density, zero potential, the polarization resistance, the corrosion rate were calculated. The magnesium release of the electrolytes was compared with the calculated values using Faraday’s law. For zone coulometry, five different trials were completed, and the electrical charge was calculated for each potential range of all magnesium alloys tested and for both electrolytes. Lower corrosion values were found in AP than in PBS⁻for all measurements. However, the rankings of the alloys are similar in both the electrolytes. Zone coulometry using small potential ranges and determination of ion release can be additional evaluation tools for magnesium alloys.