Naturally effective inhibition of microbial corrosion by bacterium-alga symbiosis on 304 stainless steel

Abstract

An environment-friendly corrosion inhibition method based on natural bacteria-alga symbiosis was proposed for stainless steel in this study. The symbiotic organisms could be adhered spontaneously on a stainless steel in the marine environment. Results showed that with the addition of the sessile algal biofilm of Phaeodactylum tricornutum, the corrosion rate of 304 stainless steel was reduced by 97.7% compared with that with only bacterium Bacillus altitudinis. This could be caused by the oxygen produced by the photosynthesis of the algae biofilm, which effectively enhanced the stability of the passive film, reduced the oxygen concentration difference under the biofilm and outside the biofilm, and thus relieved the micro-galvanic corrosion attack. Meanwhile, aided by the alga, an intelligent self-repairing corrosion product layer of iron phosphate could be preferentially deposited over the pit after pitting was initiated, which would further suppress the bio-corrosion damage and synergistically protect the 304 SS.