Synergistic effect by release of corrosion inhibitors via cellulose nanofibers in self-healing polymer coatings to prevent corrosion of carbon steel

Abstract

To inhibit the corrosion of carbon steel, epoxy polymer coatings were developed using cellulose nanofibers (CNF) and the corrosion inhibitors sodium nitrate (SN) and sodium oleate (SO). The synergistic effects of SN and SO were confirmed by measuring the polarization curves of bare carbon steel in a corrosive solution, which demonstrated the effectiveness of a first action by SN being followed by a second action by SO. In order to control the release rates for the corrosion inhibitors from polymer coatings, the addition of CNF in the polymer was effective. The optimum combination of SN, SO and CNF in the polymer coatings was 8% of SN in the first layer, then 8% and 0.5% of SO and CNF, respectively, in the second layer, which resulted in excellent self-healing properties. The controlled release for the synergistic effect of the corrosion inhibitors allowed them to generate a healing film on the damaged portions of carbon steel.