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1 – 10 of over 4000Zimin Li, Zilong Zhu, Jianqiu Wang, Meng Wang, Ting Hou, Qinghua Li and Pei Yu
Two corrosion inhibitors for closed cooling water systems, nitrite-based and mixture of nitrite and molybdate corrosion inhibitor, are often compared to each other. This study…
Abstract
Purpose
Two corrosion inhibitors for closed cooling water systems, nitrite-based and mixture of nitrite and molybdate corrosion inhibitor, are often compared to each other. This study aims to optimize these two inhibitors in terms of concentration and pH for carbon steel protection, with insights into the double layer structure on surface and its impact on corrosion inhibition.
Design/methodology/approach
Electrochemical analysis including electrochemical impedance spectroscopy and potentiodynamic test are carried out for quick assessment of corrosion inhibition efficiency and optimization, which is confirmed by immersion test and microscopic analysis. The electronic properties of the surface film are analyzed through Mott–Schottky method which provides new insights into the inhibition mechanism and the role of each component in mixture inhibitor.
Findings
Mixture of nitrite and molybdate is shown to present higher inhibition efficiency, owning to the double layer structure. Nitrite alone can form a protective surface film, whereas molybdate leads to an n-type semiconductive film with lower donor density, hence giving rise to a better inhibition effect.
Research limitations/implications
Surface after inhibitor treatment has been carefully characterized to the microscopic scale, implying the effect of micro-structure, chemical composition and electronic properties on the corrosion resistance. Inorganic corrosion inhibitors can be tuned to provide higher efficiency by careful design of surface film structure and composition.
Originality/value
Almost every study on corrosion inhibitor applies such method for quick assessment of corrosion inhibition effect. Mott–Schottky test is one of electrochemical methods that reveals the electronic properties of the surface film. Previous works have studied the surface layer mainly through X-ray photoelectron spectroscopy. This study provides another insight into the surface film treated by nitrite and molybdate through Mott–Schottky analysis, and relates this structure to the corrosion inhibition effect based on multiple analysis including electrochemistry, microscopic characterization, thermodynamics and interface chemistry.
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After obtaining his membership of the Institution of Metallurgists (now Institute of Materials), Dr Ray attended City of London Polytechnic, gaining an MSc degree in corrosion…
Abstract
After obtaining his membership of the Institution of Metallurgists (now Institute of Materials), Dr Ray attended City of London Polytechnic, gaining an MSc degree in corrosion science and engineering and a PhD in fatigue properties of steel. He was awarded the Johnson Matthey Silver Medal in 1978 for a research paper, based on his MSc Thesis, in potential sources of corrosion in transistor packages. He is a Fellow of the Institute of Materials, Institute of Corrosion and Institute of Metal Finishing.
B. Mónica Carrillo, S. Benjamín Valdez, Lucien Vevela, L. Tezozomoc Pérez, O. Lidia Vargas and W. Michael Schorr
Microbiologically induced corrosion of copper intrauterine devices “TCu380A” and “Nova T” by Enterobacter sp. in a synthetic intrauterine medium was investigated. The corrosion…
Abstract
Microbiologically induced corrosion of copper intrauterine devices “TCu380A” and “Nova T” by Enterobacter sp. in a synthetic intrauterine medium was investigated. The corrosion behaviour was evaluated applying cyclic voltammetry and Tafel Polarization. The surface morphology was determined using scanning electron microscopy, the corrosion products were analyzed using energy dispersive X‐rays and the biofilm composition was examined by Fourier transform infrared spectroscopy with an attenuated total reflectance device.
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FRENCH INSTITUTE OF CORROSION. The Centre Francais de la Corrosion (Cefracot) was recently instituted in Paris. It aims at co‐ordinating information on the science, technology and…
Abstract
FRENCH INSTITUTE OF CORROSION. The Centre Francais de la Corrosion (Cefracot) was recently instituted in Paris. It aims at co‐ordinating information on the science, technology and application of corrosion and corrosion proofing, and is a non‐profit‐making organisation. Cefracor is to take up contacts with all French institutions, and those abroad, devoted to similar ends, and is already a member of the European Federation of Corrosion. The centre has its headquarters at 28 rue Saint Dominique, Paris, 7e.
A. Al‐Mathami, H. Saricimen, R. Kahraman, M. Al‐Zahrani and S. Al‐Dulaijan
The purpose of this study was to evaluate the effectiveness of sodium dihydrogen orthophosphate as an inhibitor to slow down or prevent atmospheric corrosion of the local mild…
Abstract
The purpose of this study was to evaluate the effectiveness of sodium dihydrogen orthophosphate as an inhibitor to slow down or prevent atmospheric corrosion of the local mild steel during storage in the Arabian Gulf region. In light of the results of some preliminary studies, sodium dihydrogen orthophosphate was selected for further evaluation against atmospheric corrosion of steel after it was applied at 10 mM concentration for 1 day at room temperature.
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V. Cherian, S.K. Srivastava and M.V. Katarki
This paper seeks to determine the causes and mechanism of failure of stainless steel piping in a sulphur recovery unit of a gas‐processing plant and to recommend suitable measures…
Abstract
Purpose
This paper seeks to determine the causes and mechanism of failure of stainless steel piping in a sulphur recovery unit of a gas‐processing plant and to recommend suitable measures to avoid recurrences.
Design/methodology/approach
The integrity of the material of construction was verified using various laboratory and analytical techniques. Standard metallographic techniques were used to prepare representative samples obtained from failed stainless steel piping for metallurgical evaluation. Microstructural characterization was carried out in an inverted metallurgical microscope equipped with an imaging facility. Elemental analysis and hardness were used to confirm the identification of the material. Corrosion product/deposits were analyzed using wet chemistry supported by X‐ray diffraction analysis. Microbes were enumerated through standard methods.
Findings
The piping failed due to severe pitting corrosion, which resulted in the formation of holes. Microbial‐induced corrosion (MIC) and under‐deposit corrosion were chief contributing factors that caused the failure in stainless steel piping. In addition, the HAZ near welds at some places was found to be sensitized causing accelerated pitting corrosion at these sites.
Practical implications
The expected service life of stainless steel piping could not be realized as the piping failed due to the combined effect of MIC and under‐deposit corrosion. Periodic monitoring of sulphate‐reducing bacteria and sulphur‐oxidizing bacteria coupled with implementation of an effective biocide treatment programme in process fluid was recommended, together with the introduction of a procedure for frequent cleaning of the pipe walls to minimize under‐deposit attack.
Originality/value
The paper – a technical case study of process industry – provides an account of failure investigation. It identifies the causes and mechanism of failure and suggests suitable preventive and corrective measures. This is useful industrial experience that provides valuable information for process and plant corrosion engineers involved in the operation of this type of equipment.
Ramazan Kahraman, Huseyin Saricimen, Zuhair Omar Malaibari and Md Abdur Rauf
The purpose of this study was to investigate the performances of two inhibitors in controlling corrosion of steel products in industrial and marine atmosphere.
Abstract
Purpose
The purpose of this study was to investigate the performances of two inhibitors in controlling corrosion of steel products in industrial and marine atmosphere.
Design/methodology/approach
Corrosion rates were determined by weight loss measurements. At certain periods of atmospheric exposure, the (disc shape) specimens were retrieved and studied by scanning electron microscopy and energy-dispersive spectrometry surface analysis techniques.
Findings
Both inhibitors were effective against corrosion of steel in the early stages of the atmospheric exposure (for about two months). With further exposure to the atmosphere, their inhibition effectiveness deteriorated and was totally lost within four months. Analysis of the specimens before exposure showed that the inhibitor film was thin for both treatments, and the unexposed treated surface for both inhibitors appeared similar to the untreated unexposed specimen surface. Characterization of the specimens at different exposure periods showed fewer corrosion blisters on dicyclohexylamine nitrite- and sodium benzoate-treated surfaces than on untreated specimens.
Originality/value
The objective of this study was to characterize the surfaces of the steel products produced locally during their exposure to the industrial and marine atmosphere of the Arabian Gulf region after being treated by sodium benzoate and dicyclohexylamine nitrite in controlling the corrosion of local mild steel products. According to the literature review, this study is original and will add value to the studies of inhibition of steel corrosion under similar environments.
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Ya Nan Luo, Shi Zhe Song, Wei Xian Jin and Lei Han
The purpose of this paper is to research electrochemical testing technology as applied to in field corrosion evaluation of metallic materials and to study the corrosion behaviors…
Abstract
Purpose
The purpose of this paper is to research electrochemical testing technology as applied to in field corrosion evaluation of metallic materials and to study the corrosion behaviors of the materials exposed in different marine regions.
Design/methodology/approach
The electrode systems for in field electrochemical evaluation of metallic samples are designed and applied to monitor two types of carbon steel samples exposed both in the submerged zone and the tidal zone at a marine corrosion test station. Corrosion potential monitoring, potentiostatic square wave, electrochemical impedance spectroscopy, and electrochemical noise methods are used in the test.
Findings
It is confirmed that the electrode systems could be used for electrochemical measurement of metallic samples during exposure in the submerged zone and the tidal zone of a marine corrosion test station for long‐term test durations. The electrochemical measuring results reflect the changes and differences of the samples' corrosion behavior during exposure in different regions and they respond directly to the influence of marine environmental factors on the corrosion behaviors, especially the influence of temperature.
Originality/value
In this paper, lots of consecutive and dynamic corrosion information is obtained from field exposures. The findings provide a foundation upon which to investigate and forecast the corrosion behaviors of materials in marine environments.
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Li-Xiang Wang, Da-Hai Xia, Shi-Zhe Song, Yashar Behnamian and Likun Xu
This paper aims to quantify atmospheric corrosion by image analyses. The corrosion extent, form and distribution of corrosion product on Q235B and T91 steels exposed to a Zhoushan…
Abstract
Purpose
This paper aims to quantify atmospheric corrosion by image analyses. The corrosion extent, form and distribution of corrosion product on Q235B and T91 steels exposed to a Zhoushan marine atmosphere over one year are characterized by image analysis.
Design/methodology/approach
Image analysis of corrosion images were achieved using the gray value, wavelet analysis and fuzzy Kolmogorov–Sinai (K–S) entropy.
Findings
As corrosion becomes extensive, the gray value of corrosion images decreases, and the energy value of nine subimages after wavelength decomposition decreases. Fuzzy K–S entropy increases as localized corrosion propagates but decreases as uniform corrosion spreads.
Originality/value
The methods proposed in this work open a new way for fast corrosion evaluation of metallic materials exposed to atmospheric conditions.
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B.W. Neumaier and C.M. Schillmoller
Early this year (CORROSION TECHNOLOGY, March issue) we published the first part of a paper presented before the American Petroleum Institute's Refining Division and also the…
Abstract
Early this year (CORROSION TECHNOLOGY, March issue) we published the first part of a paper presented before the American Petroleum Institute's Refining Division and also the National Institute of Corrosion Engineers, describing the different forms of hydrogen damage and the prevention steps that were taken at the new fluid catalytic cracking unit of the Richfield Oil Corporation. At that time we announced that we hoped to publish more of this interesting paper, brought up to date. This, then, completes the work of Messrs. Neumaier and Schillmoller and describes protective steps that have been taken at the fluid unit gas plant, the evaluation of these steps, monitoring and the use of organic inhibitors.