Degradation behaviors of surface modified magnesium alloy wires in different simulated physiological environments

Abstract

The degradation behaviors of the novel high-strength AZ31B magnesium alloy wires after surface modification using micro-arc-oxidization (MAO) and subsequently sealing with poly-L-lactic acid (PLLA) in different simulated physiological environments were investigated. The results show the surface MAO micropores could be physically sealed by PLLA, thus forming an effective protection to corrosion resistance for the wires. In simulated gastric fluid (SGF) at a low pH value (1.5 or 2.5), the treated wires have a high degradation rate with a rapid decrease of mass, diameter, mechanical properties and a significant increase of pH value of the immersion fluid. However, surface modification could effectively reduce the degradation rate of the treated wires in SGF with a pH value above 4.0. For the treated wires in simulated intestinal fluid at pH= 8.5, their strength retention ability is higher than that in strong acidic SGF. And the loss rate of mass is faster than that of diameter, while the pH value of the immersion fluid decreases. It should be noted that the modified wires in simulated body environment have the best strength retention ability. The wires show the different degradation behaviors indicating their different degradation mechanisms, which are also proposed in this work.

Keywords

magnesium alloy wire / degradation behavior / surface modification / simulated physiological environment

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Acknowledgements

The work was financially supported by Science and Technology Support Program of Jiangsu Province (Grant of BE2011778) and Ph.D. Programs Foundation of Ministry of Education of China (Grant No. 20120092120048).

RIGHTS & PERMISSIONS

2014 Higher Education Press and Springer-Verlag Berlin Heidelberg