Influence of aggressive ions on the degradation behavior of biomedical magnesium alloy in physiological environment.
Various electrochemical approaches, including potentiodynamic polarization, open circuit potential evolution and electrochemical impedance spectroscopy (EIS), are employed to investigate the degradation behavior of biomedical magnesium alloy under the influence of aggressive ions, such as chloride, phosphate, carbonate and sulfate, in a physiological environment. The synergetic effects and mutual influence of these ions on the degradation behavior of Mg are revealed. Our results demonstrate that chloride ions can induce porous pitting corrosion. In the presence of phosphates, the corrosion rate decreases and the formation of pitting corrosion is significantly delayed due to precipitation of magnesium phosphate. Hydrogen carbonate ions are observed to stimulate the corrosion of magnesium alloy during the early immersion stage but they can also induce rapid passivation on the surface. This surface passivation behavior mainly results from the fast precipitation of magnesium carbonate in the corrosion product layer that can subsequently inhibit pitting corrosion completely. Sulfate ions are also found to stimulate magnesium dissolution. These results improve our understanding on the degradation mechanism of surgical magnesium in the physiological environment.
Xin
Yunchang
Y
Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China.
Huo
Kaifu
K
Tao
Hu
H
Tang
Guoyi
G
Chu
Paul K
PK
D000497:Alloys / Q000737:chemistry*; D001639:Bicarbonates / Q000737:chemistry; D002021:Buffers; D002712:Chlorides / Q000737:chemistry; D004563:Electrochemistry / Q000379:methods; D006801:Humans; D007477:Ions; D008274:Magnesium / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D008954:Models, Biological; D011199:Potentiometry / Q000379:methods; D017550:Spectroscopy, Fourier Transform Infrared; D013431:Sulfates / Q000737:chemistry; D013696:Temperature; D014961:X-Ray Diffraction
D000497:Alloys; D001639:Bicarbonates; D002021:Buffers; D002712:Chlorides; D007477:Ions; D013431:Sulfates; D008274:Magnesium