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Article
Publication date: 8 September 2012

J. González‐Sánchez, L. Dzib‐Pérez, E. Garcia‐Ochoa, G. Canto and M. Sosa‐Baz

The purpose of this paper is to quantitatively assess the pit growth rate on AISI 304L and AISI 316 austenitic stainless steels in natural seawater and 3.5 wt.% NaCl solutions…

368

Abstract

Purpose

The purpose of this paper is to quantitatively assess the pit growth rate on AISI 304L and AISI 316 austenitic stainless steels in natural seawater and 3.5 wt.% NaCl solutions through electrochemical measurements during the potentiostatic growth of pits.

Design/methodology/approach

A quantitative characterisation was carried out based on chronoamperometric measurements. The volume of dissolved metal per pit was calculated from the charge registered and Faraday's law, considering both, hemispherical and semi‐elliptical pit shapes and the density of the steels. Empirical growth laws for maximum pit depth as a function of polarisation time were obtained and compared with pits volumetric profile obtained from optical microscopy analysis and mechanical removal of material on both steels.

Findings

Electrochemical‐based calculations of localised metal dissolution per pit present acceptable fit with the real volume of dissolved metal on hemispherical pits.

Originality/value

The paper presents the quantitative relationship of the corrosion pit growth rate of stainless steels in chloride containing solution determined by chronoamperometry (electrochemical technique) through the Faraday law's, with the mechanical removal of material (pit profile) through the density of metal.

Details

Anti-Corrosion Methods and Materials, vol. 59 no. 5
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 9 January 2009

L. Dzib‐Pérez, J. González‐Sánchez, J.M. Malo and F.J. Rodríguez

The aim of this paper is to study and analyse the advantages and limitations of the scanning reference electrode technique (SRET) to detect and assess localised electrochemical…

346

Abstract

Purpose

The aim of this paper is to study and analyse the advantages and limitations of the scanning reference electrode technique (SRET) to detect and assess localised electrochemical activity based on an evaluation of the influence of the principal test parameters on the sensitivity and resolution of the technique.

Design/methodology/approach

Measurements of Ohmic potential gradients induced by ionic flux close to a point current source (PCS) were carried out using a scanning reference electrode technique (SRET) instrument, which comprised a vertical rotating working electrode and a scanning probe formed by a pair of platinum electrodes of approximately 200 μm of diameter. Ionic flux was induced by anodic polarisation applied to a gold micro‐disc electrode, which acted as the PCS. Measurements were conducted in electrolytes of ten different conductivities, using different scanning probe tips to sample surface distance and different working electrode rotation rates. The range of conductivities used included most of the possible electrolytes to which metallic materials can be in contact under real service conditions.

Findings

The SRET signal sensed from a polarised PCS showed a strong dependence on the rotation rate of the working electrode for electrolytes of low conductivity but a minimal effect on electrolytes with conductivities higher than 50 mS/cm.

Originality/value

This work presents the effect of wide variations on the electrochemical and operational conditions on the sensitivity and resolution of SRET signal response and discusses the limitations of the technique to assess localised electrochemical activity due to the effect of high conductivity electrolytes, large separation distance between the SRET scanning probe and developing dissolution and scanning rate of a the localised site.

Details

Anti-Corrosion Methods and Materials, vol. 56 no. 1
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 1 May 2006

L. Dzib‐Pérez, J. González‐Sánchez, T. Pérez, A. Juárez and P. Bartolo‐Pérez

To study the corrosion resistance of the novel alloy Al‐12.6La (wt%) manufactured using directional solidification.

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Abstract

Purpose

To study the corrosion resistance of the novel alloy Al‐12.6La (wt%) manufactured using directional solidification.

Design/methodology/approach

Samples fabricated using the Bridgman growth technique at three different withdrawal velocities were subjected to total immersion tests in distilled water and in 3.5 per cent NaCl solution and to DC polarisation tests in distilled water. XPS analyses conducted on samples after polarisation indicated the presence of an La compound in the non passive corrosion products film formed.

Findings

Anodic polarisation induced dissolution of the alloy with the formation of a non passive corrosion product film. During potentiodynamic polarisation, a sudden current increment occurred at a potential value that was more positive for samples solidified at higher rates. The corrosion resistance of this Al‐12.6%La alloy decreased as the solidification rate increased.

Originality/value

The results presented in this work are an insight to the understanding of the corrosion resistance and electrochemical behaviour of this alloy for future engineering applications and development.

Details

Anti-Corrosion Methods and Materials, vol. 53 no. 3
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 21 June 2013

Dong Liu, Huiqing Liu, Li Li, Meng Yu, Jun Gong, Wen Li and Yunxia Wang

The purpose of this paper is to assess the serious corrosion problems of the water injection system on the offshore oil field and to study the type, and effect factors and…

368

Abstract

Purpose

The purpose of this paper is to assess the serious corrosion problems of the water injection system on the offshore oil field and to study the type, and effect factors and mechanisms of corrosion on the offshore oil field in order to develop an effective corrosion inhibitor for the sea water injection system.

Design/methodology/approach

The corrosion of metal in a water injection system was studied by weight‐loss and electrochemical methods.The effect factors and mechanisms of corrosion on the offshore oil field were proposed from the trend of corrosion.

Findings

FeCO3 is the main corrosion product in the water injection system of the Chengdao Offshore Oil Field. The corrosion rate of coupons in sea water injection systems reaches a maximum peak at a temperature of 50‐60°C. The corrosion rate of coupons exposed in all three water samples increased with an increase in the dissolved oxygen concentration. When the mixed ratio of sea water and produced water and well water is 1:3:1 or 1:2:2, the corrosion rate of carbon steel is lower than is the case in pure water. The electrochemical mechanism of corrosion indicates that corrosion in the well water, produced water, and sea water samples were all controlled by the oxygen absorption process, which controlled the cathodic reaction. The corrosion rate of coupons followed the ranking order: well water; produced water; sea water.

Originality/value

This paper provides the main corrosion product in the water injection system of the Chengdao Offshore Oil Field, and provides new information on the effect factors and mechanisms of corrosion on the offshore oil field.

Details

Anti-Corrosion Methods and Materials, vol. 60 no. 4
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 21 June 2013

Xianlong Cao, Hongda Deng, Wei Lan and Pengjun Cao

The aims are to investigate the influence of different environmental parameters on atmospheric corrosion of carbon steel and to further emphasize the feasibility and importance of…

490

Abstract

Purpose

The aims are to investigate the influence of different environmental parameters on atmospheric corrosion of carbon steel and to further emphasize the feasibility and importance of atmospheric corrosion monitor (ACM).

Design/methodology/approach

The experiment includes outdoor exposure test and laboratory simulation test. ACM as an electrochemical method was adopted in order to research the effects of the environmental parameters on the atmospheric corrosion of carbon steel.

Findings

The corrosion current of ACM can respond satisfactorily to the corrosion of carbon steel caused by different environmental factors, especially relative humidity. Sulfur dioxide can greatly accelerate the corrosion of carbon steel and the importance of sulfur dioxide is closely related to its concentration and relative humidity. Copper‐accelerated acetic acid salt solution is more aggressive than neutral salt solution, which may be due to sub acidity and copper ion in the former solution.

Originality/value

Recently, ACM seems to be ignored in the research of atmospheric corrosion when some new methods come up, but in practical applications it is a simple, direct and effective method that should be attached importance. This paper further verified the feasibility and effectiveness of ACM used in monitoring atmospheric corrosion and exploring the relationship between corrosion rate and environmental parameters.

Details

Anti-Corrosion Methods and Materials, vol. 60 no. 4
Type: Research Article
ISSN: 0003-5599

Keywords

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