The inhibitory and comparative effects of Zn-Al layered double hydroxide microcontainers intercalated with benzotriazole and nitrite for corrosion protection coatings on AISI 1010 carbon steel

Resumo

The electrochemical impedance spectroscopy and the open circuit potential techniques were used to analyse coatings with layered double hydroxides intercalated with benzotriazole (BTA), nitrite (NO2), and a combination of the two. These materials were added 5% (m/m) to epoxy resin and applied on carbon steel surface as an anticorrosive system. The analyses were performed during 1000 h of salt spray chamber exposure. Morphology and particle distribution on the coatings were characterized by FEG-SEM. The LDH BTA formed a complex with zinc from the LDH layer and a phase based on ZnO/ZnOH, as shown by XRD analysis. This complex may have impaired the LDH-BTA- corrosion inhibition process, as it formed an undesired phase on Zn-Al layers. The LDH NO2- enhanced corrosion resistance, inducing formation of a passivating layer on the metal surface due to corrosion inhibitor release and chloride ion capture.  Keywords: LDH, Zn-Al- NO2-, Zn-Al- BTA-, Corrosion, Electrochemical impedance spectroscopy