Bioactivity and corrosion behavior of magnesium alloys treated by plasma electrolytic oxidation

Summary form only given. As a lightweight and nontoxic metal with mechanical properties similar to those of natural bones, magnesium based materials have attracted much interest in biomedical engineering. As the materials are both biocompatible and biodegradable, they can be used in many orthopedic and load-bearing applications. However, the poor corrosion resistance of magnesium-based biomedical implants in a physiological environment has hampered their use as substitutes for human hard tissues. Recently, plasma electrolytic oxidation (PEO) that is derived from anodic oxidation technology has been applied to treat valve-metals such as Al, Mg, Ti and their alloys. By utilizing micro-arc plasma discharges sustained at a high voltage in aqueous solutions, various oxide films can be formed on these metals to improve their surface properties such as wear and corrosion resistance as well as bioactivity. In this work, PEO treatments are conducted on magnesium alloys in different electrolytes and different voltage modes. The corrosion resistance is determined in simulated body fluids (SBF) based on the potentiodynamic polarization curves, and the surface bioactivity is investigated by monitoring the apatite inducing capability. The structure and chemistry of the plasma-formed surface oxide which exhibits a porous structure are evaluated. Our results show that the corrosion resistance and bioactivity of the PEO Mg alloys are much improved