Dissecting Anticorrosion and Antimicrobial Potency of an Ag Nanoparticle/NbC Nanocomposite Coating in a Marine Environment Containing Sulfate-Reducing Bacteria

Abstract

To mitigate the microbiologically influenced corrosion of metallic components serving in marine environments, an innovative Ag nanoparticle (AgNP)/NbC nanocomposite coating was synthesized using a double glow discharge plasma method. The coating was composed of Ag nanoparticles together with NbC nanocrystals embedded in an amorphous carbon (a-C) matrix. The incorporation of Ag into the NbC coating played a significant role in determining both the grain size and crystallographic texture of the NbC phase, as well as the bonding state of the carbon species and the surface morphology of the coating. Following immersion in sulfate-reducing bacteria (SRB)-inoculated artificial seawater, the planktonic SRB cell count for the AgNPs/NbC nanocomposite coating was found to be two and three orders of magnitude lower than those of the Ag-free NbC coating and bare Ti-6Al-4V, respectively. The electrochemical corrosion behavior of the AgNPs/NbC nanocomposite coating was evaluated and compared to the Ag-free NbC coating and bare Ti-6Al-4V in SRB-inoculated artificial seawater by using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The semiconducting properties of the oxide film grown on the nanocomposite coating were drawn from Mott–Schottky analysis. The results showed that Ag additions improved the microbiologically influenced corrosion (MIC) resistance of the NbC coating and led to the transformation of the electronic structure of the oxide film from an n-type semiconductor to a p–n heterojunction structure.

Biological fouling and corrosion resistance of Ni-based coating on AH32

“…The surface of AH32 steel was completely covered by a large number of organisms in the form of a continuous biofilm, and the bacteria was consistent with the original SRB shape [29], the shells were maintained well. The distribution of the bacteria on the surface of the Ni-based coating was vein-like, and that of the Ag-doped coating was scattered with an extremely small amount of organisms, which is in agreement with previous studies on the effect of the coatings with Ni-based and Ag addition on SRB [30,31]. Figure 5(d-f) shows the morphologies of the bacterial contaminant surfaces of the AH32, NiCrAlY, and NiCrAlY(Ag) coatings after soaking in the solution for 12 days, respectively.…”