Insight into microbiologically induced corrosion performance of magnesium in tryptic soy broth with S. aureus and E. coli

Abstract

In this research, microbiologically induced corrosion (MIC) performance of magnesium in tryptic soy broth with S. aureus or E. coli were systematically explored. The results showed that magnesium in biotic solution presented higher mass loss, thicker degradation product layer and more severe pitting corrosion compared to abiotic solution after 24 h of immersion. Electrochemical measurements including EIS spectra and polarization curve further suggested that the corrosion rate of Mg in biotic solution increased during the early stage owing to the decrease of pH, which was originated from the consumption of glucose and the resulting accumulation of acidic metabolites. However, corrosion rate subsequently decreased because of the reduction of acidic metabolites and production of alkaline compound as well as the corrosion protection provided by the corrosion product and biofilm. Moreover, the corrosion rate of magnesium in high concentration of S. aureus and E. coli solution was larger than that in low concentration of S. aureus and E. coli solution, respectively during the initial stage, but subsequently presented a reverse variation. In addition, more severe corrosion of magnesium was observed in S. aureus solution in comparison with E. coli solution. These results suggested that the MIC performance of magnesium was closely related to the concentration and species of bacteria.