The effect of chemical modification procedure on corrosion behaviour of pure magnesium in simulated body fluid: A comparison study

摘要

The corrosion behaviour of pure Mg in simulated body fluid (SBF) and the effect of chemical modification on the anticorrosion property of the metal was investigated using DEIS (dynamic electrochemical impedance spectroscopy), EIS (electrochemical impedance spectroscopy), PDP (potentiodynamic polarization), SEM (scanning electron microscopy), AFM (atomic force microscope), and pH measurement techniques for 30 h. NaOH and H_2O_2 were utilized for the chemical modification. The DEIS was used for the first time in the investigation of Mg corrosion in SBF. Results gotten indicate that, the chemical modification benefitted the anticorrosion property of the metal immensely. The charge transfer resistance of the Mg was raised from 387.80 Ω cm~2 to 775.10 Ω cm~2 and 1393.20 Ω cm~2 at 30 h of immersion. The DEIS results revealed that the protective layer formed upon NaOH modification collapsed and lost its effectiveness after 2 h of immersion in the tested medium. H_2O_2 modified surface demonstrated superior corrosion resistance and the pH of the SBF solution containing the H_2O_2 modified specimen stood at 7.58 after 30 h of immersion. The results from both the electrochemical and the surface analysis techniques were consistent.