The influence of dissolved oxygen (DO) and Shewanella algae on the corrosion behavior of pure titanium were systematically studied in this work. The formation of S. algae biofilms on titanium surface was facilitated by the anaerobic environment, which accelerated titanium corrosion. Upon the breakdown of passive film, S. algae acquired electrons from the titanium base substrate through extracellular electron transfer (EET) processes. Various EET-related genes were overexpressed by the low DO condition, leading to enhanced EET kinetics. High concentration DO increased TiO2 content and the thickness of passive film, which enhanced the protective effect and mitigated microbiologically influenced corrosion.@en

Microbially influenced corrosion (MIC) of metals exerts a negative effect on the marine environment and causes a great loss of marine facilities. Corrosion prevention in an eco-friendly and sustainable way is a difficult problem to address, especially in the marine environment. In this work, Nocardiopsis dassonville, a corrosive bacteria isolated from the South China Sea was studied by using carbon steel. The results indicate that N. dassonville caused a corrosion loss of 7.68 mg cm⁻² and a corrosion pit of 13.0 μm on the carbon steel surface, but the corrosion is inhibited in the presence of Vibrio sp. EF187016 in the medium. Vibrio sp. EF187016 preferentially occupied the carbon steel surface, forming a protective biofilm that hindered the attachment of N. dassonville. In addition, extracellular polymeric substances extracted from Vibrio sp. EF187016 was added to N. dassonvillei inoculated medium and showed a significant inhibition of MIC on carbon steel.

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Surface pretreatment is generally applied before application of protective coatings on Mg alloys, which influences surface microstructure and electrochemical activity of the substrate and has an effect on the coating properties. The effect of various pretreatment processes (sand-blasting, grinding and polishing) on the microstructure and corrosion protection performance of phosphate conversion coating (PCC) on AZ91D Mg alloy was investigated in the present study. Sand-blasting cleaning significantly increases the surface roughness and electrochemical activity of the substrate, leading to formation of a porous PCC with inferior corrosion protection performance. In the case of ground/polished Mg alloy, the uniformity and corrosion resistance of the resultant conversion coating are mainly related to the surface roughness. Relatively low surface roughness of the substrate facilitates formation of a corrosion protective PCC.

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