Influence of Surface Properties on Microbial Activity and Biofilm Attachment in Thermally Sprayed Cu-Bearing Coatings with Varied Cu Distributions

In this study, the influence of surface states (as-received versus polished state) on the antibacterial and anti-biofilm attachment properties of thermally sprayed Cu-bearing coatings was studied. Findings indicate that the Cu ion release rate remains the predominant factor influencing the short-period antimicrobial efficacy of these coatings in their as-received state. Additionally, the influence of surface states on the antibacterial efficacy varied with Cu distributions (Cu as a segregated phase within a composite versus Cu as a solute element within a single phase). During microbial corrosion testing with Desulfovibrio vulgaris over an extended exposure, Cu addition continues to exhibit a significant inhibitory effect on biofilm attachment in as-received state. In contrast to their polished counterparts, the rough surfaces of the as-received samples significantly enhanced biofilm attachment; however, this facilitating effect diminished over time. The mechanisms leading to reduced facilitation varied with Cu distribution, due to either the formation of Cu₂S in composite coatings or the preferential biofilm attachment in valley areas in coatings containing Cu as solute. Additionally, the results suggest that arc spray has greater advantages over HVOF in preparing antimicrobial corrosion coatings, as it produces more uniformly flattened splats that show inhibiting effect on biofilm attachment.