Corrosion protection of carbon steel by solvent free epoxy coating containing hydrotalcites intercalated with different organic corrosion inhibitors

Hydrotalcites intercalated with two different corrosion inhibitors: 2-benzothiazolythio-succinic acid (BTSA) and benzoate (BZ) were prepared by coprecipitation method and incorporated (1.5 wt.%) in solvent free epoxy coatings. The obtained hydrotalcites were characterized using infrared spectroscopy, X-ray diffraction, scanning electron microscopy and zeta potential measurements. The solid suspensions in epoxy resin were characterized by rheology and Turbiscan. The corrosion protection performance of the epoxy coating containing hydrotalcites applied on carbon steel was evaluated by electrochemical impedance spectroscopy, salt spray test and adhesion measurement. It was shown that the BTSA and BZ were intercalated in hydrotalcite and their loading was about 22 wt.% and 27 wt.%, respectively. The presence of BZ modified hydrotalcite (HT-BZ) improved significantly the corrosion protection of solvent free epoxy coating. Corrosion protection performance of epoxy coating containing HT-BZ was higher than that of epoxy coating containing BTSA modified hydrotalcite (HT-BTSA). The corrosion protection performance of coatings appears to depend on the dispersion degree of hydrotalcite particles in the epoxy matrix and the solubility of organic inhibitor in the electrolyte.