Improving the formation and protective properties of La-conversion coatings on brass by use of La2O3 nanoparticle incorporation with electrodeposition

The La2O3 nanoparticles incorporation and electrodeposition were used together to prepare the La-conversion coatings on brass surface in a basal solution containing rare earth salt and benzotriazole. The results showed that both of these techniques can improve the coatings formation and their protectiveness. A critical nanoparticulate La2O3 content and a critical deposition potential were observed, under which the conversion coatings had the highest protective properties. The composite La-conversion coatings could provide important protection against brass corrosion for considerable immersion periods in 3.5% NaCl solution because it ennobled the corrosion potential and decreased the anodic current.

► La2O3 nanoparticles and electrodeposition were used together to prepare conversion coatings.
► Critical nanoparticulate La2O3 content and critical deposition potential were observed.
► Electrodeposition time had important effects on the properties of coatings.
► La-conversion coatings had the function of self-protection and effective barrier.
► Inner barrier layer of coating played the important role in corrosion protection.