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Article
Publication date: 6 March 2017

Morteza Hoseinieh, Taghi Shahrabi, Morteza Farrokhi Rad and Bahram Ramezanzadeh

The aim of this paper is to investigate the influence of sour crude oil contaminant on the calcareous scale deposition under cathodic protection of carbon steel in…

Abstract

Purpose

The aim of this paper is to investigate the influence of sour crude oil contaminant on the calcareous scale deposition under cathodic protection of carbon steel in artificial seawater.

Design/methodology/approach

Electrochemical and surface characterizations are carried out using chronoamperometry, electrochemical impedance spectroscopy, scanning electron microscope/energy dispersive spectroscopy, X-Ray diffraction and Raman spectroscopy techniques.

Findings

Results showed that sour oil limited the deposit nucleation regarding its volume concentrations. The inhibition mechanism was examined to be simultaneous acts of pH reduction and mackinawite formation beside minor physical adsorption of oil molecules on steel electrode.

Originality/value

There is no paper concerning the proposed subject, and the idea of this work is fully novel which is of great significance because of the consequences of disastrous oil spill phenomena on the integrity of exposed offshore facilities in terms of optimum protection against probable corrosion mechanisms.

Details

Anti-Corrosion Methods and Materials, vol. 64 no. 2
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 27 March 2007

Mohammad Zamanzade, Taghi Shahrabi and Ali Yazdian

This study aims to evaluate the influence of pulsed cathodic protection on calcareous deposit formation on structures submerged in the synthetic sea water.

Abstract

Purpose

This study aims to evaluate the influence of pulsed cathodic protection on calcareous deposit formation on structures submerged in the synthetic sea water.

Design/methodology/approach

Chronoamperometric and CHF methods have been used to evaluate the influence of pulsed cathodic protection on decreasing the required cathodic current for protection and also decreasing the surface coverage. The morphology of the formed deposits was evaluated using scanning electron microscopy. Chemical analyses of the formed deposits were performed using energy dispersive X‐ray spectrometer and X‐ray diffraction.

Findings

It was observed that pulse frequency influenced both the structure and the composition of the deposits. The most compact aragonite layer was obtained at high frequencies and at a high off‐time. It was clearly shown that by applying currents with less than 100 Hz frequency, the deposits formed on the sample involved CaCO3 (aragonite) and Mg(OH)2 (brucite). However, the kinetics of deposits formed when applying pulse current have been improved, compared to deposits formed by conventional cathodic protection. The reason is that large electrode overpotential favors nucleation through a decrease in the energy of nucleus formation. On the other hand, by intensive decrease of surface potential, repulsion of aggressive anions such as SO42− and Cl occurs. These anions inhibit the formation of aragonite deposits.

Research limitations/implications

In order to have a better investigation of electrodeposition processes in the shorter time, the use of more advanced techniques and analysis methods such as XPS is recommended. Furthermore, EHD techniques could be used for measurements of thickness of the layers.

Practical implications

The pulsed cathodic protection method is a relatively new method for the protection of buried and submerged structures. Recently, many researches have investigated that the influence of this technique on increasing the throwing power, decreasing interference effects on neighboring structures and increasing the uniformity of current distribution under cathodic protection.

Originality/value

Very little attention has been paid in the past to the effect of pulsed CP on deposit formation. The present paper, therefore, contributes useful understanding of the mechanism and advantages of such deposits in improving the effectiveness and lowering the operational cost of cathodic protection in use on offshore structures.

Details

Anti-Corrosion Methods and Materials, vol. 54 no. 2
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 1 June 2004

Masoud Rezaei Saman Kandi, Taghi Shahrabi, Saed Reza Allahkaram and Mir Javad Geramian

Electrical industry equipment in the southern parts of Iran have sustained severe damages as a result of corrosive soil containing different kinds of salt, in combination…

Abstract

Electrical industry equipment in the southern parts of Iran have sustained severe damages as a result of corrosive soil containing different kinds of salt, in combination with the corrosive local atmosphere. The present paper is the result of investigations into the behaviour of coatings for various electrical insulators end‐fittings. In this research, the performance of Al‐Zn alloy coating was compared to conventional galvanized zinc coatings by means of atmospheric corrosion tests. The results demonstrated the higher corrosion resistance of the alloy coatings, compared to that of conventional galvanized coatings. Insulator end‐fittings generally are made of steel, which are coated with a hot‐dip galvanized coating. The combination of Al and Zn elements in this coating was demonstrated to possess better galvanic protection and lower corrosion rate than did pure zinc.

Details

Anti-Corrosion Methods and Materials, vol. 51 no. 3
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 1 September 2006

Maryam Ehteshamzadeh, Taghi Shahrabi and Mirghasem Hosseini

Aims to investigate the inhibitive effect of the new series of Schiff base molecules, namely, N, N′‐ethylen‐bis(salicylidenimine) [S1], N…

Abstract

Purpose

Aims to investigate the inhibitive effect of the new series of Schiff base molecules, namely, N, N′‐ethylen‐bis(salicylidenimine) [S1], N, N′‐isopropylen‐bis(salicylidenimine) [S2] and N, N′‐Ortho‐phenylen acetyl acetone imine, (2‐hydroxy Benzophenone imine) [S3] on corrosion of copper during acid pickling treatment in 1 M HCl solution. Effects of concentration and temperature on the inhibition efficiencies of the selected Schiff bases have been studied systematically.

Design/methodology/approach

All inhibition experiments were conducted on copper sample in 1 M HCl solution. Weight loss measurements were carried out according to the ASTM standard procedure. Polarization curves and impedance spectra were carried out in a three‐electrode cell assembly connected to an EG&G potentiostat M273 and frequency response analyzer M1025.

Findings

Results obtained revealed that the studied Schiff bases act predominantly as cathodic inhibitors. The variations in inhibition efficiencies mainly depend on the type and nature of the inhibitors. Polarization and ac impedance measurements carried out at different concentrations of studied Schiff bases revealed that these compounds are adsorbed on copper surface and the adsorption obeys Langmuir adsorption isotherm. From the adsorption isotherms, the values of equilibrium constant, Kads, and the free energies of adsorption, ΔGads, were calculated. The associated activation energy of corrosion and other thermodynamic parameters such as enthalpies and entropies have also been determined.

Practical implications

The presence of high efficiency and low cost inhibitors is essential in acid pickling treatments for protection of copper and lowering of acid consumption. In comparison with conventional copper corrosion inhibitors such as benzotriazole, this result would be considered as a step forward in determination of new corrosion inhibitor.

Originality/value

This paper reveals that Schiff bases can be successfully used for protection of copper surface in acid pickling solutions.

Details

Anti-Corrosion Methods and Materials, vol. 53 no. 5
Type: Research Article
ISSN: 0003-5599

Keywords

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Article
Publication date: 1 May 2006

Maryam Ehteshamzadeh, Taghi Shahrabi and Mirghasem Hosseini

In this paper, the main aim is to study the synergistic effects of alkanethiols upon inhibition of Schiff bases, N,N′‐ethylen‐bis and N,N′‐ortho‐phenylen‐bis in 0.5 M…

Abstract

Purpose

In this paper, the main aim is to study the synergistic effects of alkanethiols upon inhibition of Schiff bases, N,N′‐ethylen‐bis and N,N′‐ortho‐phenylen‐bis in 0.5 M sulphuric acid solutions.

Design/methodology/approach

Measurements were carried out in a three‐electrode cell assembly connected to the corrosion measurement system using software for Tafel polarization. Impedance measurements were carried out at open circuit potential using an electrochemical interface and frequency response analyzer at frequencies from 100 kHz to 10 MHz.

Findings

Results obtained revealed that at high concentrations, each of the investigated Schiff bases and 1‐dodecanethiol (DT) were good inhibitors when added separately to the corrosive media. The decrease in corrosion rate was associated with an increase in their concentrations. It was found that the presence of DT together with Schiff bases in corrosive medium increased inhibition effect, especially at low concentrations. Synergistic effect is discussed from viewpoint of their co‐adsorption. The adsorption of combined inhibitors was found to follow Langmuir isotherm. Thermodynamic calculations revealed that adsorption of combined inhibitors had a physical nature.

Research limitations/implications

In order to improve further the performance of Schiff bases and identifying their synergistic effects with other additives it is suggested that some more researches on other Schiff bases with other alkanethiol molecules must be done.

Practical implications

The results of this paper can be used for acid cleaning of carbon steel in which suitable inhibitor systems with the highest efficiency is required.

Originality/value

This paper reveals that the presence of DT molecules in solution encourage the adsorption of Schiff bases by facilitating the electrostatic co‐adsorption of Schiff base molecules through a synergistic effect.

Details

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

Keywords

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Article
Publication date: 27 March 2007

Mobin Salasi, Taghi Shahrabi and Emad Roayaei

To study and compare the inhibition effects of eco‐friendly inhibitors of sodium silicate and 1‐hydroxyethylidene 1,1 diphosphonic acid (HEDP) in corrosion control and…

Abstract

Purpose

To study and compare the inhibition effects of eco‐friendly inhibitors of sodium silicate and 1‐hydroxyethylidene 1,1 diphosphonic acid (HEDP) in corrosion control and prevention of soft water discolouration (red water) in carbon steel pipelines.

Design/methodology/approach

Electrochemical impedance and Tafel polarization measurements were used to study corrosion inhibition properties. The experiments were carried out under different concentration ratios of inhibitors. Different hydrodynamic conditions were applied to simulate pipeline fluid flow. Scanning electron microscopy (SEM) and EDAX analysis were used for surface studies.

Findings

It was observed that corrosion inhibitor combinations under static conditions showed synergistic effects at low concentrations. The inhibition efficiency and synergistic behaviours of inhibitors were enhanced as the electrolyte turbulence was increased. In addition, the inhibitor concentration value required to reach maximum inhibition decreased. It was found that at 20 ppm sodium silicate and 5 ppm HEDP, co‐inhibition efficiencies increased significantly to more than 90 per cent and the corrosion rate decreased far below 1 mpy as the electrode rotational speed was increased. Surface studies using SEM revealed the formation of a compact and uniform film of co‐inhibitors.

Practical implications

The results of this paper can be used for the development of effective, non‐toxic and economically attractive corrosion inhibitor formulations for soft water transmission pipelines.

Originality/value

The observed synergistic behaviour can be due to the incorporation of the silicate gel‐like network through organic phosphorous bonds. The hydrodynamic condition of the electrolyte leads to enhancement of inhibition efficiency, which indicates that the corrosion inhibition was mass transfer controlled.

Details

Anti-Corrosion Methods and Materials, vol. 54 no. 2
Type: Research Article
ISSN: 0003-5599

Keywords

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Article
Publication date: 17 March 2012

Ehsan Saebnoori, Taghi Shahrabi, Alireza Sabour Rouhaghdam and Majid Jafarian

The purpose of this paper is to investigate the effect of thermal treatment at low partial pressure of oxygen on electrochemical corrosion resistance of Ti‐47Al‐2Cr (at %…

Abstract

Purpose

The purpose of this paper is to investigate the effect of thermal treatment at low partial pressure of oxygen on electrochemical corrosion resistance of Ti‐47Al‐2Cr (at %) intermetallic, known as γ‐TiAl alloy.

Design/methodology/approach

The surfaces of the samples were modified by thermal treatment at different temperatures in N2 gas flow for an hour. Characterization of the modified surface layers was carried out by microscopic examinations, hardness and roughness tests, and X‐ray diffraction analyses. Potentiodynamic polarization was used to evaluate the corrosion performance of γ‐TiAl in Ringer's solution.

Findings

The results indicated that the alloy treated at 950 °C had the optimum corrosion resistance, which can be attributed to the formation of an oxide layer by the surface thermal treatment and increase of the passive layer thickness.

Practical implications

Low corrosion rate (CR), high pitting potential (Epit), and more noble corrosion potential (Ecorr) make it possible for γ‐TiAl to be considered as a candidate for biomedical applications.

Originality/value

The treatment described in the paper is a novel method for surface modification of this type of alloy and results showed that it was an effective treatment and that the corrosion resistance improved remarkably.

Details

Anti-Corrosion Methods and Materials, vol. 59 no. 2
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 11 July 2016

Bijan Bidabad and Mahshid Sherafati

This paper aims to discuss some of the operational Islamic banking features considered in ethical banking as the aspects of Rastin Banking. Ethical banking is a branch of…

Abstract

Purpose

This paper aims to discuss some of the operational Islamic banking features considered in ethical banking as the aspects of Rastin Banking. Ethical banking is a branch of “ethic economics” and a narrow expression of a number of Islamic banking aspects.

Design/methodology/approach

These features are often involved in the discussions under the topic of internal control and describe the operational characteristics of ethical banking within the framework of Rastin Banking.

Findings

This study refers to the principles of Rastin Banking, including operational, financial, economic, ethical, social, legal, international and organizational principles. Additionally, it takes into account some of the internal control systems.

Research limitations/implications

Converting ethical codes into executable laws and regulations needs sophistication, and the art of codification in this subject can be observed in the present paper.

Practical implications

As far as the ethical behaviour of the assessor and trustee is concerned, the necessities of honesty, belief, virtuosity, rectitude and compliance with moral values, as well as reward and punishment mechanisms, are operationally examined. Transparency, governance and disclosure of information are the other components. The methods of auditing, accounting, inspection and preservation of Rastin Banking achievements are amongst the other matters of concern.

Social implications

An assiduous attention to the operational details of each of the above-said discussions revealed that the Islamic banking components are capable of covering the topics and discussions beyond ethical banking.

Originality/value

This paper fulfils an identified need to solve the practical ethical problem in operational banking.

Details

International Journal of Law and Management, vol. 58 no. 4
Type: Research Article
ISSN: 1754-243X

Keywords

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