Fabricating protective epoxy-silica/CeO2 films for steel: Correlating physical barrier properties with material content

Niobia Nanofiber-Reinforced Protective Niobium Oxide/Acrylate Nanocomposite Coatings

“…By far, it was the protective coating with the most compacted and highly cross-linked internal microstructure and hence inhibited corrosive flows through the coating. 46 The trend in the magnitude of Q coating was also probed. Lower values were recorded for NB6 for both durations, relative to other nanocomposite coatings, denoting that 0.6 mg was the optimum nanofiber concentration within the coatings, above which the corrosion resistance further dropped (in NB8).…”

“…45 The nanofibers also acted as inorganic fillers within the bulk of the nanocomposite coatings in such a way as to block hydrophilic transport channels of corrosive chloride molecules and ions chloride ions. 46 Compared to the undoped coatings, those encapsulated with nanofibers possessed prolonged bulk compactness and rigidity, less porosity, and elastic recovery.…”

“…47 However, these micropathways were further blocked within more corrosion-resistant coatings (i.e., with higher nanofiber contents, e.g., NB6 and NB8) since their internal coating networks were further strengthened, in turn, blocking these ionic routes. 46 The enhanced cross-linking densities and compactness of these doped coatings contributed to reduced gross bulk porosity and improved protective efficiency in the presence of these nanofibers. In this study, I observed reduced surface defects with nanofiber contents, from 0.2 to 0.6 mg (the latter being the optimum concentration in a 20 g coating suspension).…”

“…From this trend of results, it could be deduced that the niobium oxide/acrylate coating matrix encapsulated with 0.6 mg of niobia nanofibers had superior barrier performance. 46,47 Except for NB6 matrix, the extrapolated values of E corr were also tending toward positive values with increasing concentrations. This trend denotes a mixed though predominantly anodic corrosion kinetics for coated steel substrates relative to the bare substrate.…”

“…Like Q coating , higher Q dl values were obtained for all coatings at prolonged exposure duration and this is consistent with increased rate of electrolyte ion diffusion. 46,49 The charge transfer resistance (R ct ) followed the same trend as R coating ; its place within the second time constant at lower frequency represents the interphase close to the metal surface. This parameter represents the resistance of the metal/coating interface and rightly offers an idea about the onset of corrosion and coating disbonding from the steel surface.…”