Pitting corrosion of rheocast A356 aluminium alloy in 3.5wt.% NaCl solution

Arrabal, R.; Mingo, B.; Pardo, Á.; Mohedano, M.; Matykina, E.; Rodrı́guez, Ismael

doi:10.1016/j.corsci.2013.04.023

Cited by 186 publications

(146 citation statements)

References 49 publications

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“…1), acting as cathodic areas and with a mean particle size of 10 µm. Although copper in solid solution improves aluminium resistance to pitting corrosion [8,11], increasing the copper content leads to the formation of these intermetallics, which are responsible for pitting corrosion [11]. Initial porosity of MA-Al compacts with or without copper is similar, however, the pitting area after immersion for 96 h increases from 11.69% for 0Cu to 20.27% for 2Cu.…”

Section: Resultsmentioning

confidence: 99%

“…Pitting corrosion is a localized form of corrosion producing small bites in a metal. Corrosion by pitting in aluminium alloys is a very complex process that can be affected by various factors such as the type of aggressive ion and its concentration, type of intermetallics formed, and the electrochemical activity associated with these intermetallics [6][7][8]. Since it is an electrochemical corrosion, the corrosion potential is defined as the potential at which the anodic and cathodic current densities * corresponding author; e-mail: beatriz@uhu.es are the same (point of interception between the anodic and cathodic branch in the polarization curves).…”

Section: Introductionmentioning

confidence: 99%

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Effect of Copper Addition on Pitting Corrosion of MA-Al

et al. 2016

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This paper is intended to highlight the effect of copper addition on the pitting corrosion resistance of aluminium-base powder metallurgy parts. Results obtained on these mechanically alloyed (MA) specimens are compared with parts of MA-Al without added copper, as well as with commercial aluminium alloys. Immersion tests from 2 to 96 hours in 3.5% NaCl solutions, and potentiostatic techniques, were used to study the pitting corrosion. It was concluded that copper addition, in a similar way that in commercial aluminium alloys, produces a negative effect on the pitting corrosion resistance, because of the formation of Al2Cu. These precipitates produce galvanic cells that favour the specimen pit. Therefore, increasing the copper content of MA-Al, although improving their ductility, worsens the pitting corrosion resistance of these alloys.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of Copper Addition on Pitting Corrosion of MA-Al

et al. 2016

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“…Se puede observar que con la adición de LiClO 4 , se produce una zona de pseudopasivación seguida de un incremento abrupto de la corriente y a continuación una pendiente más pronunciada, comparándose con la curva obtenida en la solución sin electrolito soporte. Según [22][23][24][25][26], las curvas con 0,01M y 0,001M de perclorato en etanol tienen la misma forma que el de una aleación de aluminio que sufre corrosión localizada en forma de picado, ya que describen un potencial de picado cercano -0.5V (-500mV), posterior a una zona de pseudopasivación. Además, la transpasivación ocurre a corrientes relativamente elevadas, por lo que se puede considerar que el material seguiría estando en forma activa.…”

Section: Polarización Potenciodinámicaunclassified

Efectos del uso de electrolitos soportes en ensayos electroquímicos de la aleación Al-4%Mg expuesta a bioetanol combustible

et al. 2018

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Efectos del uso de electrolitos soportes en ensayos electroquímicos de la aleación Al-4%Mg expuesta a bioetanol combustibleEffects of the use of support electrolytes in electrochemical tests of Al-4wt.% Mg alloy exposed to bioethanol fuel RESUMENEl crecimiento de la demanda de energía a nivel mundial incide directamente en el consumo de los combustibles a base de petróleo, incrementando el impacto negativo por el uso de los mismos y la disminución de las reservas de crudo. Así nace una oportunidad para el uso de combustibles de mayor eficiencia, de bajo impacto ambiental y, por sobre todo, de naturaleza renovable. El bioetanol es un biocombustible que cumple con dichas características, pero posee cierta agresividad desde el plano electroquímico sobre los sistemas metáli-cos de uso convencionales, requiriéndose una buena selección de materiales para su uso y manejo. En la evaluación de las propiedades frente a la corrosión de los materiales metálicos expuestos a bioetanol, se debe tener en cuenta la baja conductividad propia de estos compuestos orgánicos para evitar dificultades sobre el desarrollo de los ensayos y la mala interpretación de resultados. Existen en la actualidad métodos para compensar la caída óhmica producida por el medio electrolítico orgánico, siendo uno de los más usados el de adición de sales solubles en concentraciones definidas. En este trabajo se evalúan los efectos secundarios de la adición de diferentes concentraciones de CH 3 COOK y LiClO 4 como electrolito soporte al bioetanol, cuando se realizan medidas electroquímicas de Polarización Potenciodinámica y Espectroscopía de Impedancia Electroquímica (EIS) exponiendo una aleación de aluminio y magnesio a dicha solución.Palabras clave: aleación aluminio-magnesio, corrosión, electrolito soporte, etanol. ABSTRACTThe growth of world energy demand directly affects the consumption of petroleum-based fuels, increasing the negative impact of the use of these fuels and the decrease of crude oil reserves. This creates an opportunity for the use of fuels that are more efficient, of low environmental impact and, above all, of a renewable nature. Bioethanol is a biofuel that complies with these characteristics, but it has some aggressiveness from the electrochemical plane over conventional metallic systems, requiring a good selection of materials for its use and handling. In the evaluation of the corrosion properties of metal materials exposed to bioethanol, the low conductivity of these organic compounds must be taken into account to avoid difficulties in the development of the tests and the misinterpretation of results. There are currently methods to compensate for the ohmic fall produced by the organic electrolytic medium, one of the most used being the addition of soluble salts in defined concentrations. This work evaluates the effects of the addition of different concentrations of CH 3 COOK and LiClO 4 as support electrolyte to bioethanol, when electrochemical measurements of Potenciodynamic Polarization and Electrochemical Impedance Spectroscopy...

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“…However, there were always more pits in the eutectic regions than in any of the aluminum particles. This could be due to the difference of potential between phases (presence of galvanic cells [18]). Pit density tended to increase when the eutectic was at a higher proportion.…”

Section: Speckle Patternmentioning

confidence: 99%

Etching Method to create a Random Speckle Pattern on Semi-Solid Cast A356 Aluminium for DIC in-situ strain measurements

Segolle

Santos

Kasvayee

et al. 2017

jcme

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Aluminum semi-solid casting is constantly evolving, as it offers a combination of reduced shrinkage porosity and gas entrapment defects together with high productivity and an extended die-life. The relationship between the microstructure and stress-strain behavior is not well-understood due to its non-conventional microstructure. In-situ tensile testing, combined with optical microscope and Digital Image Correlation (DIC), has been used for local strain distribution measuements in cast irons. The critical capability was an etching technique to generate a micro-scale random speckle pattern with a sufficiently high speckle density to enable the sufficient spatial resolution of displacement and strain. The current paper focuses on the development of a pit etching procedure for the semi-solid cast A356 aluminum alloy to study local strain accommodation on the microstructure during tensile loading. The critical challenge of this procedure was the generation of homogeneously distributed pits on both the primary aluminum and eutectic regions. Therefore, a heated solution used for wet-etch aluminum in microfabrication was modified as well as a process adapted to generate pits with suitable characteristics. In-situ tensile tests were performed attached to an optical microscope to record the microstructure and displacements during loading. DIC software was used for analysis. The procedure was validated through a comparison between the resulting Young´s moduls using standard tensile testing and the DIC process on the speckle pattern generated. A good fit between the two methods for Young´s modulus was found. The spatial resolution obtained was, however, not sufficient to fully resolve the strain gradients in the microstructure, but it did reveal large strain variations in the microstructure.

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Pitting corrosion of rheocast A356 aluminium alloy in 3.5wt.% NaCl solution

Cited by 186 publications

References 49 publications

Effect of Copper Addition on Pitting Corrosion of MA-Al

Effect of Copper Addition on Pitting Corrosion of MA-Al

Efectos del uso de electrolitos soportes en ensayos electroquímicos de la aleación Al-4%Mg expuesta a bioetanol combustible

Etching Method to create a Random Speckle Pattern on Semi-Solid Cast A356 Aluminium for DIC in-situ strain measurements

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