Degradation behavior of pure magnesium immersed in different corrosive media

Objective:To observe the corrosion behavior of pure magnesium in different corrosive media,and explore the possible degradation mechanism.Methods:According to ASTM-G31-72 standard used simulated body fluid(SBF) and Dulbecco's modify Eagle medium(DMEM)for immersion media to immerse pure magnesium.Measured calcium,magnesium ion concentration and system pH changes in the different time point.The changes of material surface morphology were investigated by scanning electron microscopy,EDS and XRD.Results: After immersing 8 days,the samples in SBF could not observe the complete shape,while the samples' shape were completed in DMEM.The magnesium ion release quantity and calcium consumption in SBF solution are obviously higher than that of the DMEM solution.The changes of pH in two kinds of corrosion medium did not present too big difference,and the pH was maintained at about 10.0 finally.The product of pure magnesium which soaked in the two kinds of corrosion medium presented big difference.Samples' surface in the SBF system generated magnesium hydroxide,and emerged a small amount of magnesium phosphate precipitation.While in DMEM,there has been a lot of magnesium monohydrogen phosphate,magnesium phosphate,and a small amount of magnesium hydroxide crystals.Conclusion:The SBF system of the corrosion rate was significantly higher than DMEM.Pure magnesium corrosion products generated differently at different time points in the SBF system and DMEM.