Microbially deposited manganese and iron oxides on passive metals - their chemistry, distribution, and consequences for material performance

Abstract

316L stainless steel and Ti-6A1-4V corrosion coupons exposed to fresh river water ennobled the open circuit potential (OCP) to values of +365 mVsce and +400 mVsce , respectively. ToF-SIMS spectra indicated that the biominerals on the metal surfaces area a mixture of Fe2O3, Mn3O4 on partially ennobled coupons. Biomineralized manganese and iron oxides on the 316L stainless steel surfaces, regardless of the oxidation states, endanger the material integrity in a similar manner, as evidenced by the elevated OCP and increased cathodic current density upon mild polarization.