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

Anelize Seniski,Gilberto Teixeira Carrera,Mariana D’Orey Gaivão Portella Bragança,Rafael Frasson Monteiro,Kleber Franke Portella

doi:10.1590/s1517-707620200002.1064

Anelize Seniski, Gilberto Teixeira Carrera + Show 3 more

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https://doi.org/10.1590/s1517-707620200002.1064

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Abstract

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

Highlights

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
The layered double hydroxides (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

Summary

Introduction

The atmospheric corrosion of metals is an electrochemical process that starts when a thin film electrolyte layer is formed on the exposed metal. The corrosion process depends on a series of factors, such as the length of time that the surface is wet, the electrolyte pH, temperature, exposure conditions, composition of the metal, properties of the formed oxide, atmospheric pollution, etc. When iron or carbon steel alloys are exposed to the atmosphere, a thin layer of magnetite (Fe3O4) is formed, covered by a layer of FeOOH. A strategy used to control metallic corrosion is the use of barriers, such as polymeric coatings. During the useful life of the material, the coating mechanical properties can be altered, leading to faults that propagate and expose the substrate to the atmosphere. The aggressive ions (such as chloride ions), water and oxygen penetrate through them, and corrosion processes starts [4,5]

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