The pit morphology on copper in chloride- and sulphate-containing solutions

The anodic electrochemical behavior of copper in bromide medium, in the absence and presence of hexamethylenetetramine (HMTA), has been studied, using electrochemical and spectroelectrochemical techniques. The copper dissolution in the absence of HMTA was dependent on mass transport of bromide ions. A porous CuBr ®lm was formed at positive overpotentials. The ®lm growth mechanism followed the nucleation, growth and superposition (NGS) model, with instantaneous nucleation and a diusion controlled growth of a three dimensional ®lm. In the presence of the inhibitor, a passivant Cu/HMTA/Br À ®lm was observed. This ®lm has slow growth kinetics, favored by mass transport. The inhibitory eect was observed for the potential range between 0 mV and +800 mV (SCE). A maximum inhibitory eciency, near 100%, was observed for 15 mM HMTA. The nature of the passivant ®lm was con®rmed by in situ surface-enhanced Raman scattering (SERS) and SEM/EDX measurements. #

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“…20±50 mm of diameters. Similar pit formation processes have been observed for copper dissolution in chloride and sulfate media [31].…”

Section: Resultssupporting

confidence: 77%

Copper dissolution in bromide medium in the absence and presence of hexamethylenetetramine (HMTA)

Brolo

Temperini

Agostinho

1998

Electrochimica Acta

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“…74 Copper in the presence of oxygen forms rich-layers of CuO/CuCO 3 (outer layer), followed by Cu 2 O (inner layer). 79 Similar oxide layers on copper seem to occur in O 2 -rich biodiesel. The pits on the copper surface exposed to the biodiesel appear to be formed by the substitution of oxygen ions from Cu 2 O through the destruction of the CuO layer.…”

Section: Metallic Corrosion Mechanisms and The Formation Of Corrosionmentioning

confidence: 90%

The oxidative stability of biodiesel and its impact on the deterioration of metallic and polymeric materials: a review

Zuleta¹,

Baena

Ríos³

et al. 2012

J. Braz. Chem. Soc.

142

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O objetivo deste artigo é analisar as principais questões com relação às estabilidades oxidativa e de armazenamento de biodiesel e como elas afetam diferentes materiais metálicos e poliméricos presentes em peças de automóvel e em estruturas de armazenamento de biodiesel. Adicionalmente, este trabalho apresenta uma revisão das técnicas para a medição da estabilidade oxidativa e para avaliação da degradação de materiais metálicos e poliméricos. Quando biodiesel é oxidado, ocorre uma série de mudanças nas suas propriedades, tais mudanças afetam não só a qualidade do biodiesel, mas também as propriedades dos materiais que estão em contato com o biodiesel. Com a oxidação, propriedades do biodiesel como o índice de acidez, índice de peróxidos e viscosidade aumentam, entretanto os índices de iodo e teor de ésteres metílicos diminuem. As alterações das propriedades químicas e físicas do biodiesel podem afetar a integridade e a estabilidade dos materiais que estão em contato com o combustível. A atual situação relacionada com a estabilidade dos materiais revistos neste artigo poderia limitar o uso extensivo de biodiesel, como tem sido proposto em vários países, e deveria ser considerada como um fenômeno de grande importância na tecnologia de biodiesel.The purpose of this paper is to analyze the main issues concerned with the oxidative and storage stabilities of biodiesel and how they affect different metallic and polymeric materials present in automotive parts and in biodiesel storage structures. In addition, this work presents a review of the techniques used for measuring the oxidative stability and for evaluating the degradation of metallic and polymeric materials. When biodiesel is oxidized, a series of changes in its properties occurs. These changes not only affect biodiesel quality, but also the properties of the materials that are in contact with it. Upon oxidation, biodiesel properties like the acid value, peroxide value and viscosity increase, while the iodine value and the content of methyl esters decrease. The changes in the chemical and physical properties of biodiesel can affect the integrity and stability of the material. The situation reviewed in this paper, which talks about the stability of materials, could limit the extensive use of biodiesel. Such measures have been proposed in several countries, and it is a topic of great importance for biodiesel technology.

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“…Sulfate and sulfite ions were also found to act as inhibitors, although SO 3 2-is oxidized in solution to SO 4 2-ion. Interestingly, sulfate ions exhibit a synergistic effect when added to chloride ions increasing the corrosion rate in case of pure copper (Mankowski et al, 1997;Duthil et al, 1996). Their accelerating effect is a consequence of their large degree of mobility and interaction with the oxide film .…”

Section: Effect Of Composition Microstructure and The Environment Onmentioning

confidence: 99%

Prediction of Corrosion of Advanced Materials and Fabricated Components

Anderko¹,

Engelhardt²,

Łencka³

et al. 2007

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The pit morphology on copper in chloride- and sulphate-containing solutions

Cited by 78 publications

References 5 publications

Copper dissolution in bromide medium in the absence and presence of hexamethylenetetramine (HMTA)

Copper dissolution in bromide medium in the absence and presence of hexamethylenetetramine (HMTA)

The oxidative stability of biodiesel and its impact on the deterioration of metallic and polymeric materials: a review

Prediction of Corrosion of Advanced Materials and Fabricated Components

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