Study of the correlation between corrosion resistance and semi-conducting properties of the passive film of AISI 316L stainless steel in physiological solution

In this work the corrosion resistance of AISI 316L biomedical stainless steel was assessed through electrochemical impedance spectroscopy (EIS) measurements in Hanks' solution at 37?degrees C. Specimens were immersed in the electrolyte during 21 days. Semi-conducting properties of the passive film naturally formed on the surface of the metallic material during the test were evaluated through the MottSchottky approach. The aim was to investigate the correlation between corrosion resistance and semi-conducting properties in the physiological solution. The corrosion resistance was found to decrease with the immersion time. The density of defects in the passive film increased accordingly as indicated by the MottSchottky plots. The passive film presented a semi-conducting behavior with a duplex character. Above the flat band potential the behavior was typical of an n-type semiconductor whilst below such value it was typical of a p-type semiconductor. The results from EIS measurements and MottSchottky were in good agreement, suggesting that the corrosion resistance of biomedical stainless steels may be associated with the semi-conducting properties of the passive films formed during immersion in physiological medium.