A New Approach to the Determination of the Cathodic Protection Period in Zinc-Rich Paints

Abreu, C.M.; Izquierdo, M.; Merino, P.; Nóvoa, X.R.; Pérez, C.

doi:10.5006/1.3283955

Cited by 85 publications

(68 citation statements)

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“…iQ-16 ' 8 [7] C¡ = 3,35 • 10-13 e [8] Sustituyendo [7] y [8] en la ecuación [4] se obtiene una capacidad total para cada uno de estos elementos cilindricos de: Qemento = 4 > 20 ' 10 " 16 e (F/elemento) [9] Para 1 cm 2 de electrodo y un espesor de película de 58 |im, el número de estos elementos en serie es de 6, y en paralelo, suponiendo un empaquetamiento simple, es de 1,11 • 10 6 , por lo tanto, C P=-…”

Section: Comportamiento Dieléctricounclassified

“…Habitualmente, el estudio del mecanismo de acción de las PRZ se ha realizado utilizando técnicas como inspección visual, curvas de polarización y sobre todo impedancia electroquímica (1). El comportamiento electroquímico de estos recubrimientos ha sido explicado considerando circuitos equivalentes de tipo RC con o sin control por difusión (2 y 3), o bien circuitos basados en el modelo de línea de transmisión (4 y 5), con un mecanismo inicial que implica la activación del zinc por disolución del óxido de zinc nativo (6) previa al establecimiento de la protección galvánica, seguida de una protección de tipo barrera como consecuencia de la acumulación de productos de corrosión no solubles en los poros de la pintura (7).…”

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Influencia de distintos medios agresivos en la acción protectora de las pinturas ricas en zinc

Abreu¹,

Izquierdo²,

Nóvoa³

et al. 1999

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Resumen En este trabajo se pretende determinar la influencia de distintos agentes corrosivos atmosféricos en la protección anticorrosiva que ejercen las pinturas ricas en zinc de base silicato inorgánico. Sobre las muestras pintadas, y una vez han curado, se depositan periódicamente disoluciones de sulfato y de cloruro, tanto de forma independiente como conjunta. Con objeto de determinar la validez de los ensayos de inmersión, habitualmente utilizados en este tipo de estudios, las pinturas se exponen en cámara de humedad a 20 °C y 60 % de humedad relativa, lo que sería equiparable a ambientes naturales relativamente secos y que, sin embargo, permiten la corrosión del zinc. La evolución de las pinturas se estudia mediante espectroscopia de impedancia electroquímica. Los espectros obtenidos se interpretan en función de modelos de circuitos equivalentes. Esta metodología permite establecer que el mecanismo de protección está influido, tanto por la presencia de agentes contaminantes, como por las condiciones de exposición. Los resultados ponen de manifiesto la rápida evolución a un mecanismo de protección tipo barrera.Palabras clave: Pinturas ricas en zinc. Contaminantes. Espectroscopia de impedancia electroquímica. Corrosión del zinc. Corrosión atmosférica. Influence of different aggressive media on the protective behaviour of zinc rich paints AbstractThe aim of the present work is to determine the influence that different atmospheric agents have in steel protection by zinc rich paints based on inorganic silicate binder. The presence of pollutants in the atmosphere has been simulated by periodical deposition of sulphate and/or chloride solutions on the surface of the samples. With the aim of determining the validity of immersion tests, usually used in these types studies, the samples were kept in a controlled atmosphere at 20 °C and 60 % RH. These exposition conditions could represent a relative dry atmosphere allowing the zinc corrosión. Electrochemical impedance spectroscopy was employed to follow the time evolution of the studied paints. The corresponding impedance spectra were modelled using an electrical equivalent circuit approach. This methodology allows establishing that pollutants as well as weathering conditions define the protecting mechanism of these zinc rich paints. The results show a fast evolution towards a barrier-type protecting mechanism.

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Section: Comportamiento Dieléctricounclassified

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Influencia de distintos medios agresivos en la acción protectora de las pinturas ricas en zinc

Abreu¹,

Izquierdo²,

Nóvoa³

et al. 1999

REVMETAL

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“…6) Abreu et al examined the electrochemical impedance spectroscopy of ZRP-coated steel immersed in 3% NaCl solution. 7) They found from the transient of the resistance of the ZRP layer that the protection was shifted from initial cathodic protection to the barrier protection in the later stage. They suggested that the grain size of powder zinc should be uniform to extend the period of the cathodic protection stage.…”

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confidence: 99%

Corrosion Process of Inorganic Zinc-Rich Painted Steel Exposed to a High-Chloride Atmospheric Environment

et al. 2018

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The corrosion protection behavior of an inorganic zinc-rich paint (IZRP) layer on steel after exposure for five years in Okinawa, relatively high-chloride atmosphere, was studied. Zinc particles were uniformly dissolved in the IZRP-coated steel, independent of the distance from the IZRP surface. From XRD, FT-IR, Raman spectroscopy and EPMA analyses, Zn 5 (OH) 8 Cl 2 H 2 O and ZnO were generated in the entire corrosion layer. Mg and Ca were observed in the outer area. We proposed the corrosion process of IZRP-coated steel from a detailed analysis of the corrosion products.

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“…116,118,119 In the case of Zn rich primers, the cathodic protection range is estimated to be at or below~−0.78 V SCE for steel. 120,121 On the other hand, in the case of Mg-rich primers, the corrosion potential of the underlying metal (such as an Al alloy~−0.64 V SCE in 3% NaCl) could also be maintained well below its pitting potential during contact with Mg-rich particles in the primer (~−0.93 V SCE in 3%NaCl). 120,122 The oxides/hydroxides of the active metal particles (with an approximate size of 30-40 µm 122 ) could also serve to provide long-term protection to the underlying metal substrate as reported by Bierwangen et al Indeed, the Mg-rich primer system was reported to provide protection after a 3000 h Prohesion exposure and up to 6000 h under ASTM B117 salt spray testing when a top coat was applied.…”

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Chromate replacement: what does the future hold?

Gharbi

Thomas

Smith³

et al. 2018

npj Mater Degrad

185

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The ubiquitous use of chromium and its derivatives as corrosion preventative compounds accelerated rapidly after the second industrial revolution, with such compounds now integral to modern society. However, the detrimental impact of chromium compounds on the environment and human health has prompted the need to revisit the majority of current industrial corrosion protection measures. This review retraces the origins of chromium replacement motivations, introducing the various legislative actions aimed at diminishing the use of chromium compounds, and critically reviews alternative corrosion preventative technologies developed in the recent decades to now. The review, herein, is intended for a broad audience in order to provide a concise update to an increasingly timely issue.

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A New Approach to the Determination of the Cathodic Protection Period in Zinc-Rich Paints

Cited by 85 publications

References 11 publications

Influencia de distintos medios agresivos en la acción protectora de las pinturas ricas en zinc

Influencia de distintos medios agresivos en la acción protectora de las pinturas ricas en zinc

Corrosion Process of Inorganic Zinc-Rich Painted Steel Exposed to a High-Chloride Atmospheric Environment

Chromate replacement: what does the future hold?

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