Biocorrosion behaviour of magnesium alloys under pseudo-physiological conditions

Abstract

Permanent metallic implants are widely used as hard issue replacements and cardiovascular intervention devices. However, specific drawbacks with permanent implants lead to the search for degradable metallic biomaterials. Magnesium and magnesium alloys have been highly considered as Mg is essential to bodies and has a high biocorrosion potential. In this study, the corrosion behaviour of pure magnesium and AZ31magnesium alloy in physiological conditions (Hank’s solution) has been systematically investigated in both static and dynamic conditions. It was found that both materials gradually degraded at a rate of mm/year. The electrochemical tests indicated that the pure Mg has a lower anodic polarisation current and high polarisation resistance, which indicated lower degradable rate. In static applications, such as osteosynthesis implants, the hydrogen release might be an issue; for dynamic applications such as stent, relatively constant pH resulted in high degradation rate. Surface coating is developed to reduce the material’s degradation rate and make the biocorrosion controllable.