Corrosion rates of reabsorbable Mg-based materials coated with phytic acid

The development of temporary protective coatings on magnesium implants is a priority in the biomedical field. In the present study, corrosion rates were determined by various techniques for powder metallurgy Mg and AZ31 magnesium alloy uncoated and coated with phytic acid (PA). Weight loss measurements, potentiodynamic polarisation, and electrochemical impedance spectroscopy were performed to monitor the corrosion evolution in a phosphate-buffered saline solution at 37°C. The corrosion rates of all samples determined from weight losses were higher than those obtained by electrochemical techniques. According to electrochemical data, the initial corrosion current density of the coated samples decreased by three orders of magnitude as compared with that of the bare substrates. However, the protective effect weakened with the testing time due to the presence of microcracks in the PA conversion coating, which indicated the potential applicability of the coated AZ31 alloy as a biodegradable and resorbable temporary implant material for bone repair.