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Article
Publication date: 1 June 2004

S.R.F. Batista and S.E. Kuri

Duplex stainless steels are excellent materials for industrial applications and their use has increased in the oil, chemical, petroleum (offshore), and electric power…

1094

Abstract

Duplex stainless steels are excellent materials for industrial applications and their use has increased in the oil, chemical, petroleum (offshore), and electric power industries. Pitting resistance equivalent (PRE) is the first parameter used to characterise the pitting and crevice corrosion resistance. Nevertheless, there are other aspects to be considered, such as the precise values of the PRE in the α and γ phases and the selective corrosion processes that may occur at grain boundaries. This paper indicates that α/γ and α/σ interfaces are preferential sites for the nucleation and growth of pits and for consequent selective corrosion, with increasing tendency in the ferritic phase. In addition, the selective dissolution potential is more reactive (and therefore, is of greater significance) than the pitting potential.

Details

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

Keywords

Article
Publication date: 1 November 2006

F.S. Santos, J.E. May and S.E. Kuri

Amorphous and nanocrystalline FeCo‐based alloys present excellent soft magnetic properties and high Curie TC temperatures. At ambient temperatures, these alloys are…

Abstract

Purpose

Amorphous and nanocrystalline FeCo‐based alloys present excellent soft magnetic properties and high Curie TC temperatures. At ambient temperatures, these alloys are subject to electrochemical corrosion, which causes degradation of their magnetic properties. This paper seeks to characterize the microstructure and evaluate the corrosion resistance of Fe36Co36Zr7Si10B11 and Fe33.5Co33.5Nb7Si15B11 alloys.

Design/methodology/approach

These alloys are solidified at different cooling rates.

Findings

The corrosion resistance, which is found to depend on the microstructure, decreases as the cooling rate increases in the interval of 50‐150°C.

Originality/value

Builds on existing knowledge of the microstructure and corrosion resistance of Fe36Co36Zr7Si10B11 and Fe33.5Co33.5Nb7Si15B11 alloys.

Details

Anti-Corrosion Methods and Materials, vol. 53 no. 6
Type: Research Article
ISSN: 0003-5599

Keywords

Article
Publication date: 16 October 2018

Fidel Amésquita Cubillas, Oswaldo Morales and Gareth H. Rees

This paper aims to focus on the influences that lead individuals to create and continue with operating informal business ventures in Peru. It seeks to empirically identify…

Abstract

Purpose

This paper aims to focus on the influences that lead individuals to create and continue with operating informal business ventures in Peru. It seeks to empirically identify the factors that are significant in forming the intentions of entrepreneurs to begin or continue with their informal businesses.

Design/methodology/approach

The theory of planned behaviour (TPB) is applied using data gathered from interviews with informal domestic gas cylinder sellers using a formally conducted survey. Using structural equation modelling, the constructs that influence the entrepreneurial intentions of informal gas sellers in Lima, Peru, are determined.

Findings

Of the three TPB constructs, attitude was found to be most significant, reflecting a belief of informality’s benefits, social norm was also significant, revealing the importance of the opinions of family, whereas perceived behavioural control was found not to be significant.

Originality/value

These results provide confirmation of a policy approach developed to address the high rates of business informality while maintaining safety in a highly regulated industry segment. By providing insight into factors beyond economic drivers, the study reveals that an understanding of the prevailing social environment is important for the development of policies dealing with informal entrepreneurship.

Details

Journal of Entrepreneurship in Emerging Economies, vol. 10 no. 3
Type: Research Article
ISSN: 2053-4604

Keywords

Article
Publication date: 29 November 2018

Simbarashe Fashu and Rajwali Khan

Thin coatings are of great importance to minimize corrosion attack of steel in different environments. A review of recent work on electrodeposition and corrosion…

Abstract

Purpose

Thin coatings are of great importance to minimize corrosion attack of steel in different environments. A review of recent work on electrodeposition and corrosion performance of Zn-Ni-based alloys for sacrificial corrosion protection of ferrous substrates is presented. The purpose of this study is to provide a systematic comparison of the corrosion resistances of Zn-Ni alloy coatings. The review contains key and outstanding comparisons of references for the period from 2007 to 2017. Binary and ternary Zn-Ni-based alloys were compared and contrasted to provide a good knowledge basis for selection of best coating system to steel substrates.

Design/methodology/approach

This article is a review article.

Findings

Zn-Ni-(X) alloys show great potential for replacing Cd metal in corrosion protection of steel substrates.

Practical implications

The research on plating of binary Zn-Ni alloys from aqueous electrolytes is now well advanced and these alloys show improved corrosion resistance compared to pure Zn. Pulse plated and compositionally modulated multilayer Zn-Ni alloy coatings showed enhanced corrosion properties compared to direct plated Zn-Ni coatings of similar composition.

Originality/value

The work on electrodeposition of Zn-Ni based alloys from ionic liquids is still scarce, yet these liquids show great promise in improving corrosion resistance and reducing coating thickness when compared to aqueous electrolytes. Advanced plating techniques in ionic liquids such as electromagnetic, compositionally modulated multilayer, pulse plating, ternary alloys and composites should be considered as these electrolytes avoid water chemistry and associated defects.

Details

Anti-Corrosion Methods and Materials, vol. 66 no. 1
Type: Research Article
ISSN: 0003-5599

Keywords

Article
Publication date: 28 October 2014

J.L. Li, C.T. Qu, S.D. Zhu, L. Liu and Z.Q. Gao

The purpose of this study was to investigate the pitting resistance and assess the critical pitting temperature (CPT) of a super martensitic stainless steel, 00Cr13Ni5Mo2…

Abstract

Purpose

The purpose of this study was to investigate the pitting resistance and assess the critical pitting temperature (CPT) of a super martensitic stainless steel, 00Cr13Ni5Mo2, made in China, considering especially the difference in the pitting corrosion resistance between the domestic super martensitic stainless steel and an imported one.

Design/methodology/approach

Potentiodynamic sweep tests were applied to investigate the effects of four NaCl concentrations (weight per cent) of 1, 3.5, 9 and 17, and four testing temperatures of 30, 50, 75 and 90°C on the pitting resistance of the domestic super martensitic stainless steel in the presence of CO2. Potentiostatic sweep tests were utilized to determine the CPT. Furthermore, chemical immersion exposures, implemented according to the appropriate standard were used to evaluate the difference in the pitting corrosion resistance between the domestic super martensitic stainless steel and an imported one. In addition, the morphology of pits was analyzed using a scanning electron microscope.

Finding

The pitting potential of the domestic super martensitic stainless steel decreased with an increase in NaCl concentration and temperature in the presence of CO2. The CPT of the domestic super martensitic stainless steel measured by potentiostatic polarization was 41.16°C. Two types of typical corrosion pits, closed pits formed at 35°C and open pits formed at 50°C, were observed. Furthermore, compared to the super martensitic stainless steel made in Japan, the domestic one was better in terms of pitting potential, corrosion rate and the density of the pits, but worse in terms of the depth of the pits, which may result in a risk of corrosion perforation of tubing and casings.

Originality/value

The paper highlights that chloride ions, temperature and the presence of CO2 play an important role on the pitting resistance of super martensitic stainless steel.

Details

Anti-Corrosion Methods and Materials, vol. 61 no. 6
Type: Research Article
ISSN: 0003-5599

Keywords

Article
Publication date: 23 July 2020

Wei Luo, Lei Hu, Yimin Xv, Jian Zhou, Wentao Xv and Mi Yan

This paper aims to focus on an assessment of the electrochemical corrosion performance of bulk NC copper in a variety of corrosion environments.

Abstract

Purpose

This paper aims to focus on an assessment of the electrochemical corrosion performance of bulk NC copper in a variety of corrosion environments.

Design/methodology/approach

The electrochemical corrosion behavior of bulk nanocrystalline (NC) copper prepared by inert gas condensation and in situ warm compress technique was studied by using potentiodynamic polarization and electrochemical impedance spectroscopy tests in de-aerated 0.1 M NaOH solution.

Findings

NC copper exhibited a typical active-passive-transpassive behavior with the formation of duplex passive films, which was qualitatively similar to coarse-grain (CG) copper. Although a compact passive film formed on NC copper surface, the corrosion resistance of NC copper was lower in comparison with CG copper. The increase in corrosion rate for NC copper was mainly attributed to the high activity of surface atoms and intergranular atoms. These atoms led to an enhancement of passive ability and an increase of dissolution rate of passive film in oxygen-deficiency solution. For NC copper, the corrosion resistance decreased as grain size increased in NC range.

Originality/value

The difference in corrosion resistance between bulk NC copper and its CG counterpart is dependent upon the corrosion solution. In a previous work, the potentiodynamic polarization tests revealed that NC copper bulks (grain size 48, 68, 92 nm) had identical corrosion resistance to CG copper bulk in naturally aerated 0.1 M NaOH solution. The results might be related to the dissolved oxygen in the medium.

Details

Anti-Corrosion Methods and Materials, vol. 67 no. 5
Type: Research Article
ISSN: 0003-5599

Keywords

Article
Publication date: 13 March 2019

Altaf Ahmad, Ranveer Kumar and Anil Kumar

This paper aims to identify an inhibitor to protect rebar corrosion in concrete.

Abstract

Purpose

This paper aims to identify an inhibitor to protect rebar corrosion in concrete.

Design/methodology/approach

The authors use the simple method of polarization and calculate the change in open-circuit potential and corrosion current density.

Findings

Sodium molybdate is an efficient inhibitor compared with sodium tungstate for rebar corrosion in concrete.

Research limitations/implications

This paper has limitation of 0.0001 M concentration of inhibitors for 400 days of exposure in 3.5 per cent sodium chloride solution.

Originality/value

The research focused on the concentration of both inhibitors in the range from 0.1 to 0.0001 M, which resulted in greater structural protection from corrosion in adverse conditions, such as coastal areas.

Details

Anti-Corrosion Methods and Materials, vol. 66 no. 3
Type: Research Article
ISSN: 0003-5599

Keywords

Article
Publication date: 1 January 2014

Guofu Qiao, Yi Hong, Tiejun Liu and Jinping Ou

The aim of this paper was to investigate the passive corrosion control and active corrosion protective effect of the reinforced concrete structures by electrochemical…

Abstract

Purpose

The aim of this paper was to investigate the passive corrosion control and active corrosion protective effect of the reinforced concrete structures by electrochemical chloride removal (ECR) method and inhibitors approach, respectively.

Design/methodology/approach

The concentration of aggressive chloride ion distributed from the reinforcing steel to the surface of the concrete cover was analyzed during the ECR processes. Besides, the half-cell potential, the concrete resistance R c , the polarization resistance R p and the capacitance of double layer C dl of the steel/concrete system were used to characterize the electrochemical performance of the concrete prisms.

Findings

The effectiveness of ECR could be enhanced by increasing the amplitude of potential or prolonging the time. Inhibitor SBT-ZX(I) could successfully prevent the corrosion development of the reinforcing steel in concrete.

Originality/value

The research provides the scientific basis for the practical application of ECR and inhibitors in the field.

Details

Anti-Corrosion Methods and Materials, vol. 61 no. 1
Type: Research Article
ISSN: 0003-5599

Keywords

Article
Publication date: 21 September 2018

Isam Tareq Abdullah and Sabah Khammass Hussein

The purpose of this paper is to optimize the welding parameters: rotating speed and plunging depth of carbon steel and pure copper joints using friction stir spot welding…

Abstract

Purpose

The purpose of this paper is to optimize the welding parameters: rotating speed and plunging depth of carbon steel and pure copper joints using friction stir spot welding (FSSW) with the aid of the design of experiments (DOE) method.

Design/methodology/approach

Carbon steel and pure copper sheets were welded using the FSSW technique with a cylindrical tool and without a probe. The welding parameters were: rotating speed: 1,120, 1,400 and 1,800 RPM and plunging depth: 0.2 and 0.4 mm. The welding process was carried out both with and without pre-heating. The welded specimens were analyzed using a shear tensile test. A microstructural investigation at the optimum conditions was carried out. The results were analyzed and optimized using the statistical software Minitab and following the DOE method.

Findings

Pre-heating the sample and increasing the rotating speed and plunging depth increased the tensile shear force of the joint. The plunging depth has the biggest effect on the joint efficiency compared with the rotating speed. The optimum shear force (4,560 N) was found at 1,800 RPM, 0.4 mm plunge depth and with pre-heating. The welding parameters were modified so that the samples were welded at 1,800 RPM and at plunging depths of 0.45–1 mm in 0.05 mm steps. The optimized shear force was 5,400 N. The fractured samples exhibited two types of failure mode: interfacial and nugget pull-out.

Originality/value

For the first time, pure copper and carbon steel sheets were welded using FSSW and a tool without a probe with ideal joint efficiency (95 percent).

Details

Multidiscipline Modeling in Materials and Structures, vol. 14 no. 5
Type: Research Article
ISSN: 1573-6105

Keywords

Article
Publication date: 7 January 2019

Maria Krambia-Kapardis

The purpose of this paper is to provide an adequate account of anti-corruption agency (ACA) ineffectiveness and propose the kind of ACA that would hold the promise of…

Abstract

Purpose

The purpose of this paper is to provide an adequate account of anti-corruption agency (ACA) ineffectiveness and propose the kind of ACA that would hold the promise of success. The paper draws on legitimacy theory, legal process and the notion of integrity of purpose.

Design/methodology/approach

This paper contextualizes the establishment and proliferation of ACAs; explores different ways of conceptualizing them; examines the broad range of factors that have underpinned ACA ineffectiveness and utilizes both legitimacy theory and the notion of the integrity of purpose.

Findings

The one-ACA-model-fits-all approach in corruption-control has been an abysmal failure. Disentangling the reasons for ACA ineffectiveness reveals various endogenous and exogenous factors. It also emphasizes the crucial importance of integrating both legitimacy theory and integrity of purpose in a revamped ACA concept that meets the corruption-control challenge.

Practical implications

It is possible to design and implement an effective ACA by avoiding various factors that have been shown to seriously undermine corruption control efforts by also drawing on legitimacy theory, legal process and integrity of purpose.

Social implications

Corruption in both the public and private sectors cannot be controlled in isolation from other socio-economic problems. An effective ACA is one that fosters integrity and is considered legitimate by its stakeholders.

Originality/value

While there have been some articles the past two decades discussing the effectiveness of ACAs in particular countries, this is the first paper to account for the overall ACA ineffectiveness also using legitimacy theory, legal process and integrity of purpose to revamp the ACA concept.

Details

Journal of Financial Crime, vol. 26 no. 1
Type: Research Article
ISSN: 1359-0790

Keywords

1 – 10 of 185