Electrolyte penetration through epoxy coatings electrodeposited on steel

Mišković‐Stanković, Vesna; Dražić, D.M.; Teodorović, M. J.

doi:10.1016/0010-938x(94)00130-x

Cited by 132 publications

(73 citation statements)

References 17 publications

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“…Various electrochemical techniques have been applied to show that defect-free organic coatings provide sufficient protection of the coated metal against corrosion although typical anticorrosive coatings are sufficiently permeable to water and oxygen so that the transport of these molecules can not determine the rate of cathodic delamination in naturally encountered environments [22][23][24][25]. In order to balance the charge of the negatively charged hydroxyl ions (e.g.…”

Section: Introductionmentioning

confidence: 99%

Influence of substrate topography on cathodic delamination of anticorrosive coatings

Sörensen

Kiil

Dam‐Johansen

et al. 2009

Progress in Organic Coatings

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The cathodic delamination of a commercial TiO 2 pigmented epoxy coating on abrasive cleaned cold rolled steel has been investigated. The rate of delamination was found to depend on interfacial transport from the artificial defect to the delamination front and thereby the substrate topography, whereas the coating thickness had little influence. The presence of a significant potential gradient between the anode and the cathode and the dependency of the delamination rate on the tortuosity of the steel surface suggests that cathodic delamination is controlled by migration of cations from the defect to the delamination front. This means that abrasive blasting, to some extent, can be applied to control and minimize the observed rate of cathodic delamination. The lifetime of the species causing disbondment suggested that sodium hydroxide or potassium hydroxide and not peroxide species or radicals are the causative agents at free corrosion potential (i.e. without impressed current).

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Section: Introductionmentioning

confidence: 99%

Influence of substrate topography on cathodic delamination of anticorrosive coatings

Sörensen

Kiil

Dam‐Johansen

et al. 2009

Progress in Organic Coatings

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“…Water uptake in epoxy is reported to be faster than that of anions such chloride ions [43,45]. The H2O uptake is thought to occur via diffusion of water through the polymer matrix, however, it is possible that other structures may play a role such as penetrative pores reported for electrodeposited epoxys without inhibitors [41,46,47]. In the samples studied here, where the inhibitor is present, there may be accelerated H2O transport through the LDE components.…”

Section: Transport and Corrosionmentioning

confidence: 84%

“…Generally, water uptake is rapid upon exposure of inhibited coatings to an electrolyte [35,41,43,44] as was the case for the epoxy film presented here which was saturated in less than four hours [43,45]. The uptake is not so fast in the pure polymer where better barrier properties are developed and H2O penetration may take many days [35,41,42].…”

Section: Transport and Corrosionmentioning

confidence: 87%

“…Local variation in density of the polymer itself such as with the LDE components mentioned above, v. Mixed pore networks particularly those that are not connected to the external surface but reach the metal/coating interface or vice versa Summarising with respect toFigure 5, the types of pore networks mentioned in the literature have a range of scales from that of molecular pore volume (case (i)) to microporous defects (case (ii)). For example, penetrative pathways through the polymer itself may range in scale from micropores 41 or domains with different polymer density (LDE) [1,2] down to pathways through the intramolecular volume [22,35]. There is also likely to be a strong dependence on the chemistry of the polymer and the cross linking agent [22,23].…”

Section: Transport and Corrosionmentioning

confidence: 99%

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Structure and Transport in Coatings from Multiscale Computed Tomography of Coatings—New Perspectives for Eelectrochemical Impedance Spectroscopy Modeling?

Hughes

Trinchi

et al. 2016

Electrochimica Acta

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“…It can be seen that the pore resistance decreases and coating capacitance increases for the first few days, denoting the entry of electrolyte into the epoxy coating. 16,17 This is the first step of electrolyte penetration through an organic coating and it is related to water uptake, when molecules of pure water diffuse into the micropores of the polymer net according to Fick's law. 18 After that initial period, the values of pore resistance and coating capacitance reach a plateau and remain almost unchanged over a long time period, indicating the maintenance of good protective properties due to the existence of the passive oxide film (anodic, chromatophosphate and phosphate layer).…”

Section: Resultsmentioning

confidence: 99%

The study of corrosion stability of organic epoxy protective coatings on aluminium and modified aluminium surfaces

Lazarević¹,

Mikovic-Stankovic²,

Kačarević-Popović³

et al. 2005

J. Braz. Chem. Soc.

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Revestimentos de epóxido foram obtidos através da eletrodeposição catódica de uma resina epóxi sobre alumínio e superfícies de alumínio modificadas (fosfatadas, cromadas-fosfatadas e anodizadas) usando o método potenciostático (concentração da resina de 10% em massa, temperatura de 27 °C e tensão de 250 V). A corrosão desses revestimentos foi investigada durante exposição ao NaCl 3% usando espectroscopia de impedância eletroquímica (EIS) e medidas de polarização. A partir da medida da dependência da resistência, da capacitância e da permissividade, obtida da EIS, e da velocidade da reação de desprendimento de hidrogênio no banho de eletrodeposição, obtida das curvas de polarização, pode-se observar que o revestimento epóxido sobre o alumínio e superfícies de alumínio modificadas constitui uma boa barreira ao transporte de agentes corrosivos. O tempo de contato entre o eletrólito e a superfície do alumínio sob o revestimento é muito maior no caso das superfícies modificadas por cromagem-fosfatização e anodização.Epoxy coatings were formed by cathodic electrodeposition of an epoxy resin on aluminium and modified aluminium surfaces (phosphatized, chromatized-phosphatized and anodized aluminium) using a constant voltage method (resin concentration 10 wt.%, temperature 27 °C, applied voltage 250 V). The corrosion behavior of these coatings was investigated during exposure to 3% NaCl using electrochemical impedance spectroscopy (EIS) and polarization measurements. From the dependence of resistance, capacitance and relative permittivity of the coating, obtained from EIS, on the rate of hydrogen evolution reaction in the electrodeposition bath, obtained from polarization curves, it can be observed that the epoxy coating on aluminium and modified aluminium surfaces is a good barrier against the transport of corrosive agents. The time corresponding to contact between electrolyte and aluminium surface under the coating is greater in the case of surface modification by chromato-phosphatized and anodized aluminium than in the case of phosphatize one.

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Electrolyte penetration through epoxy coatings electrodeposited on steel

Cited by 132 publications

References 17 publications

Influence of substrate topography on cathodic delamination of anticorrosive coatings

Influence of substrate topography on cathodic delamination of anticorrosive coatings

Structure and Transport in Coatings from Multiscale Computed Tomography of Coatings—New Perspectives for Eelectrochemical Impedance Spectroscopy Modeling?

The study of corrosion stability of organic epoxy protective coatings on aluminium and modified aluminium surfaces

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