Corrosion protection of carbon steel by an epoxy resin containing organically modified clay

This study focusses on the use of montmorillonite clay (MMT) treated with an organic compound (aminotrimethylphosphonic acid (ATMP)) and dispersed in an epoxy resin to improve corrosion protection of carbon steel. X-ray diffraction was performed to verify that the individual silicate layers were separated and dispersed in the epoxy resin. Corrosion resistance of the coated steel was evaluated by electrochemical impedance spectroscopy (EIS) and local electrochemical impedance spectroscopy (LEIS). Three systems were tested: the epoxy clear-coat, the epoxy resin containing 2 wt.% clay and the epoxy resin containing 2 wt.% clay modified byATMP (ATMP-modified clay). From conventional EIS, it was shown that the incorporation of clay or ATMP-modified clay in the epoxy matrix significantly improved the barrier properties of the coating. The corrosion resistance of the carbon steel coated by the epoxy resin containing ATMP-modified clay was higher than that obtained for the system containing non-treated clay. Local electrochemical measurements performed on scratched samples revealed the inhibitive role of ATMP at the carbon steel/coating interface

THE INFLUENCE OF ZrO2/SILANE PRE-TREATMENT ON CORROSION RESISTANCE OF POWDER COATING

Carbon steel was treated by immersion in silane doped hexafluorozirconic acid solution. Treated surface was characterized by field emission scanning electron microscopy (FE-SEM) and electrochemical methods. The effect of ZrO2/silane pretreatment on the protective properties of powder coating was studied by adhesion measurement and electrochemical impedance spectroscopy (EIS). The obtained results showed that the morphology and electrochemical characteristics of ZrO2/silane film depend on solution pH. Surface morphology was uniform and compact at solution pH = 4. The best corrosion performance obtained with the film formed in solution with pH and immersion time of 4 and 4 mins, respectively. The ZrO2/silane pretreatment significantly improved adhesion and corrosion resistance of powder coating on carbon steel

Mécanismes de protection apportée à l'acier par un revêtement époxy chargé en hydrotalcites modifiés par différents inhibiteurs organiques de corrosion: étude électrochimique

peer reviewed« Mécanismes de protection apportée à l'acier par un revêtement époxy chargé en hydrotalcites modifiés par différents inhibiteurs organiques de corrosion: étude électrochimique». Résumé Cette étude s'inscrit dans le développement de revêtements organiques respectueux de l'environnement pour la protection des substrats métalliques sans solvant et sans chromates. La protection à la corrosion de l'acier au carbone est obtenue dans cette étude par synthèse d'hydrotalcites intercalés avec des inhibiteurs présentant une fonction carboxylique ou carboxylate et incorporés dans une résine époxy sans solvant. Les inhibiteurs retenus sur base de leur efficacité électrochimique sont l'acide benzothiazolytthiosuccinique, le benzoate de sodium et le sebacate de sodium. Les hydrotalcites sont synthétisées par la méthode de co-précipitation et caractérisées par analyses FTIR et DRX pour vérifier la position intercalaire des inhibiteurs. Leur morphologie est lamellaire (TEM) avec des tailles de particules entre 200 et 500 nm. Le relargage des inhibiteurs de corrosion en milieu chloruré agressif est déterminé (mesures TOC et UV-Vis) en fonction du temps et pour différentes concentrations en chlorures. Les courbes de polarisation anodiques indiquent que les hydrotalcites modifiées sont des inhibiteurs anodiques efficaces (efficacité supérieure à 80%). Les hydrotalcites modifiées sont incorporées et dispersées dans la résine époxy. Les performances des revêtements sont évaluées par spectroscopie d'impédance électrochimique en milieu neutre chloruré. Les échantillons griffés ont également été exposés au test brouillard salin. Les résultats seront discutés en considérant le nombre de groupes fonctionnels, la solubilité des inhibiteurs de corrosion et les interactions avec l'hydrotalcite et le substrat métallique

Layered double hydroxides as containers of inhibitors in organic coatings for corrosion protection of carbon steel

The present work focuses on the use of layered double hydroxides (LDH) as containers for corrosion inhibitors in an epoxy coating. 2-Benzothiazolylthio-succinic acid (BTSA), used as corrosion inhibitor, was intercalated by co-precipitation in magnesium-aluminum layered double hydroxides. The obtained LDH-BTSA was characterized by infrared spectroscopy, X-ray diffraction and scanning electron microscopy. BTSA release from LDH-BTSA in NaCl solutions was investigated by UV-vis spectroscopy. The inhibitive action of LDH-BTSA on carbon steel corrosion was characterized by electrochemical methods and the protective properties of an epoxy coating containing LDH-BTSA were evaluated by electrochemical impedance spectroscopy. It was shown that the BTSA was intercalated in the layered double hydroxide and its loading was about 33%. The BTSA release was dependent on the NaCl concentration in the electrolyte. The polarization curves obtained on the carbon steel sample showed that the LDH-BTSA is an anodic inhibitor. Its efficiency was about 90% at a concentration of 3 g/l. The impedance results showed that the incorporation of LDH-BTSA (3%) in the epoxy matrix improved the corrosion protection of the carbon steel

Incorporation of an indole-3 butyric acid modified clay in epoxy resin for corrosion protection of carbon steel

In the present work, indole-3 butyric acid (IBA) was inserted between montmorillonite clay platelets by cation exchange. The clay treated with the organic compound (IBA-modified clay) was then dispersed in an epoxy resin at a low concentration (2 wt.%). IBA was chosen to act both as an inhibitor and an adherence promoter. The effect of the IBA-modified clay on the microstructure and on the protective properties of the epoxy coating deposited on carbon steel was evaluated by a thermostimulated-current (TSC) method and by electrochemical impedance spectroscopy (EIS). The TSC measurements showed the specific action of IBA-modified clay which decreased the molecular mobility of the polymer chain by comparison with the pure epoxy. Impedance measurements corroborated the role of the modified clay on the barrier properties of the coating which remained high as a function of exposure time in a 0.5 M NaCl solution. The corrosion resistance of the carbon steel coated with the epoxy resin containing IBA-modified clay was significantly higher than that obtained with the clear coat. Polarization curves plotted in the presence of an artificial defect demonstrated the inhibitive role of IBA at the carbon steel/coating interface. The good adherence of the coating was seen during salt spray test

Hydrotalcite modified coatings for corrosion protection of steel and Zn sacrificial layers

peer reviewe

MODIFICATION OF GRAPHENE OXIDE BY CURCUMIN AND APPLICATION IN POLYURETHANE COATING

Curcumin modified graphene oxide (GO-CR) was prepared using adsorption method and polyurethane (PU) coating containing 0.3 wt% GO-CR was prepared on carbon steel. Synthesized GO-CR was characterized by fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and zeta potential measurement. Corrosion protection property of polyurethane coating containing GO-CR was evaluated and compared with blank polyurethane coating and coating containing GO by electrochemical impedance spectroscopy. The results showed that GO-CR has layer structure like GO with lower crystallinity. In GO-CR structure curcumin was attached on GO surface. The presence of curcumin on GO-CR surface provided corrosion inhibition action for PU coating and also improved the dispersion of GO in PU coating

Corrosion inhibition of pure zinc in 0.1 M NaCl by acyl thiosemicarbazide derivatives

peer reviewedThe use of organic compounds as inhibitors of zinc alloys has shown great promise because they were able to either be adsorbed on the surface or chemically react with the metallic surface to form a barrier coating between the metallic surface and aggressive media [1]. The corrosion inhibition mechanisms of organic inhibitors was related to the sharing of the outer orbital electrons of heteroatoms and π-orbitals to unoccupied d-orbital spaces within corroded metals, which formed new coordination bonds and subsequently, a protective coating [2, 3]. The impact of picolinoyl N4-phenylthiosemicarbazide (HL) concentrations on the corrosion resistance of pure zinc substrate were investigated in this study. The inhibitory action of 10-5, 10-4, and 10-3 M HL on pure zinc substrate in 0.1 M NaCl was studied by electrochemical methods such as electrochemical impedance spectroscopy and potentiodynamic polarization, whereas the surface morphology and chemical compositions of all the surface substrates after exposure to 0.1 M NaCl with and without HL were observed via X-ray photoelectron spectroscopy (XPS), and electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS). The results indicated that the HL inhibitor can be considered as a mixed-type inhibitor with a predominant effect on the anodic zinc dissolution. The HL exhibited excellent corrosion inhibition of 99.26 % at 10-3 M.4617 - ARES PRD 2020 - Vietnam - Renforcement de l'expertise du centre de compétences en protection contre la corrosion et en éléctrochimie - Fédération Wallonie Bruxelle

CORROSION PROTECTION OF CARBON STEEL USING ZIRCONIUM OXIDE/SILANE PRETREATMENT AND POWDER COATING

Surface pretreatment plays important role in improvement of corrosion resistance and adhesion of organic coatings. A new generation of metal pretreatments based on nanosize zirconium oxide or ogranosilane film has been investigated recently as an alternative method to phosphatation. In this paper, ZrO2/silane composite film on carbon steel was prepared and characterised by field emission scanning electron microscopy, energy dispersive X-ray spectrum and electrochemical measurements. The effect of ZrO2/silane surface treatment on the protection properties of powder coating was studied by salt spray test and adhesion measurement. The results obtained showed that ZrO2 was rapidly precipitated on the steel surface after first 1 minute immersion and ZrO2/silane film formed after 4 minutes immersion give best protective properties. Powder coating on carbon steel with ZrO2/silane pretreatement has equivalent protection performance like powder coating with  phosphate pretreatment

Study of formation and corrosion resistance of Ce-doped ZnAl hydrotalcite layers on different zinc alloys coated steel

peer reviewedDue to their unique structure, hydrotalcite (HT) can trap and hold aggressive corrosive anions in their positively charged layers [1]. Moreover, hydrotalcite can be directly grown on the metal surface and form a physical protective layer avoiding the exposure of substrate to corrosive environments [2]. Recently, various methods have been investigated to prepare HT layers as smart anti-corrosion coatings on surfaces of zinc alloys and galvanized steel [3, 4]. However, the preparation and corrosion resistance assessment of “in-situ” La/Ce-doped HT layer on galvanized steel substrates have not been still well investigated. This study aims at investigating the influence of composition and roughness of the zinc coated steel substrates such as hot-dip galvanized steel, Zn-Al coated steel, and Zn-Al-Mg coated steel substrates on the formation and the anti-corrosion properties of Ce-doped ZnAl HT layers grown by the “in-situ” synthesis method at pH 12. The structural and morphological properties of Ce-doped ZnAl HT layers were detected by Fourier-transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and electron microscopy/energy dispersive X-ray spectroscopy. The corrosion behaviour of layers was recorded by electrochemical methods such as potentiodynamic polarization and electrochemical impedance spectroscopy during 168 h immersion in sodium chloride (0.1 M). Besides, the inhibitive effect of Ce-doped ZnAl HT layers on all corrosion substrates was discussed in detail.4617 - ARES PRD 2020 - Vietnam - Renforcement de l'expertise du centre de compétences en protection contre la corrosion et en éléctrochimie - Fédération Wallonie Bruxelles9. Industry, innovation and infrastructur