NiMo and NiMo with embedded CeO2 nanoparticles (100 nm) were tested as antimicrobial coatings (~15 μm thickness) on Ti (titanium) surfaces using an electrochemical process for heat exchanger applications onboard marine vessels. Preliminary static biofouling and biocorrosion (also known as microbiologically influenced corrosion) assessments were carried out in glass bottles using pure-strain Desulfovibrio vulgaris, a sulfate reducing bacterium (SRB), in deoxygenated ATCC 1249 medium at 37°C, and using an alga (Chlorella vulgaris) mixed with general heterotrophic bacteria (GHB) in enriched artificial seawater at 28°C. It was found that NiMo/CeO2 was much more effective than NiMo in preventing SRB biofilm formation with an efficacy of 99% reduction in D. vulgaris sessile cells after 21-day incubation. The NiMo/CeO2 coating also exhibited a 50% lower corrosion current density compared to the uncoated Ti against SRB corrosion. Both NiMo and NiMo/CeO2 coatings achieved 99% reduction in sessile algal cells. Confocal laser scanning microscopy (CLSM) biofilm images indicated a large reduction of sessile GHB cells. The CLSM images also confirmed the biocidal kill effects of the two coatings. Unlike polymer coatings, the “metallic” costings are heat conductive. Thus, the corrosion resistant antifouling coatings are suitable for heat exchanger applications.

Subject
Biofouling, Coatings, Electrochemical cells, Composition, Metal surfaces, Biofilms, Efficacy, Incubation, Heat exchangers, Corrosion resistance, Risk reduction, Pitting resistance equivalent number, Wrought metals
Keywords:
Biofilm, Biofouling, Biocorrosion, Coating, Antimicrobial, Heat Exchanger
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2022
Association for Materials Protection and Performance (AMPP)
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