Effect of pH Value on Wear Behavior of AZ80 Magnesium Alloy in Simulated Body Fluid.

Magnesium alloy, with high specific strength and stiffness, biocompatibility and degradability, has become a potential orthopedic implant material. However, the application of magnesium alloys in the medical field is limited by the excessively fast corrosion rate and poor wear resistance. The corrosion and wear behaviors of AZ80 magnesium alloy in simulated body fluid (SBF) with different pH values (pH 4, 7.4 and 9) were investigated by electrochemical and reciprocating wear tests respectively to understand the corrosive wear behavior of orthopedic magnesium alloys. The wear morphology was characterized by three-dimensional white light interference profiler, scanning electron microscope (SEM), energy dispersive x-ray spectroscopy (EDS) and x-ray diffractometer (XRD). It was found that the test environment played a major role in the corrosion and wear behavior of the specimen. The corrosion resistance of the specimen enhanced with increasing pH value. Compared with the dry environment, the lubrication effect of SBF was not observed. Although the coefficient of friction (COF) of the specimen was not decreased by SBF, the wear volume of the specimen was significantly reduced by SBF. The synergistic effect of corrosion and wear caused the wear rate of the specimen in SBF to decrease with the increase of pH value. The stability of the block Mg(OH)₂ film enhanced with the pH value, which was the reason why the corrosion and wear resistance of the specimen in SBF improved with the pH value. [ABSTRACT FROM AUTHOR]