Thermally sprayed Cu-based coatings show promise for combating microbiologically influenced corrosion (MIC) within natural gas pipelines. However, the efficacy of Cu-bearing coatings against MIC over prolonged exposure to bacterial fluids remains unclear. To examine the effect of Cu distribution on the prevention of MIC, two types of Cu-containing coatings were prepared: stainless steel (SS)-Cu composite coatings and Monel 400 coatings with Cu in solid solution. These coatings were deposited using high velocity oxy-fuel (HVOF) and wire arc spray (WAS) techniques. Dynamic flow corrosion testing was utilized to examine the influence of Cu concentration and distribution on biofilm attachment and pit formation. The results show that SS-Cu composite coatings exhibit preferential Cu dissolution when exposed to Desulfovibrio vulgaris solution, significantly reducing biofilm attachment over the short-term period (7 days) which correlated with the release rate of Cu ions. However, accelerated Cu ion release led to Cu2S deposition on sample surfaces, diminishing anti-biofilm properties with prolonged exposure (28 days). Pit depth measurements indicated a correlation between pit formation and Cu ion release throughout the exposure period, with bio-generic H2S likely contributing to increased pit corrosion. Utilizing the Preference Ranking Organization Method for Enrichment Evaluation (PROMETHEE), the anti-MIC performance of coatings were ranked based on biofilm thickness, biofilm coverage, pit depth, antimicrobial effect, and splat thickness. The ranking placed WAS Monel with Cu in solid solution as the most effective coating, attributed to its thin laminar structure, enhanced corrosion resistance, and antimicrobial properties. Cu in solid solution was concluded to be more effective in resisting MIC of Desulfovibrio vulgaris under dynamic flow conditions compared to Cu existing as segregated phase within composite coatings.
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