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1 – 10 of 166Duplex stainless steels are excellent materials for industrial applications and their use has increased in the oil, chemical, petroleum (offshore), and electric power industries…
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.
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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 subject to…
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.
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Junyu Shi, Shengli Ling, Yinjie Kuang, Yonggang Tong, Yongle Hu and Dunying Deng
The purpose of this paper is to reveal the effect of microstructure on the corrosion behavior of CoCrNi alloy in 3.5 Wt.% NaCl solution.
Abstract
Purpose
The purpose of this paper is to reveal the effect of microstructure on the corrosion behavior of CoCrNi alloy in 3.5 Wt.% NaCl solution.
Design/methodology/approach
The as-cast CoCrNi alloy was prepared by arc melting, and the cold-rolled and annealed alloys were prepared by processing the as-cast alloy.
Findings
The experimental results showed that a protective passivation film was formed on the surfaces of these CoCrNi MEA, and the stability and compactness of alloys increased in the sequence of cold-rolled, as-cast and annealed CoCrNi alloys. The annealed CoCrNi alloys had the best pitting resistance.
Originality/value
This study proposes the effect of the microstructure of CoCrNi alloy on corrosion resistance.
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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 the…
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.
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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 performance of…
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.
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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.
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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.
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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.
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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 chloride…
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.
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Dalei Zhang, Xinwei Zhang, Enze Wei, Xiaohui Dou and Zonghao He
This study aims to improve the corrosion resistance of TA2-welded joints by superhydrophobic surface modification using micro-arc oxidation technology and low surface energy…
Abstract
Purpose
This study aims to improve the corrosion resistance of TA2-welded joints by superhydrophobic surface modification using micro-arc oxidation technology and low surface energy substance modification.
Design/methodology/approach
The microstructure and chemical state of the superhydrophobic film layer were analyzed using scanning electron microscopy, energy dispersive X-ray spectroscopy, three-dimensional morphology, X-ray diffraction, X-ray photoelectron spectroscopy and Fourier transform infrared absorption spectroscopy. The influence of the superhydrophobic film layer on the corrosion resistance of TA2-welded joints was investigated using classical electrochemical testing methods.
Findings
The characterization results showed that the super hydrophobic TiO2 ceramic membrane was successfully constructed on the surface of the TA2-welded joint, and the construction of the super hydrophobic film greatly improved the corrosion resistance of the TA2-welded joint.
Originality/value
The superhydrophobic TiO2 ceramic membrane has excellent corrosion resistance. The micro nanostructure in the superhydrophobic film can intercept air to form an air layer to prevent the corrosion medium from contacting the surface, thus, improving the corrosion resistance of the sample.
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