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21 – 30 of over 6000As pitting corrosion is probably the most damaging type of wet corrosion, an understanding throughout industry of this phenomenon, which is the condition between complete immunity…
Abstract
As pitting corrosion is probably the most damaging type of wet corrosion, an understanding throughout industry of this phenomenon, which is the condition between complete immunity to attack and general corrosion, is essential. This article is concerned with pitting corrosion in general, but it also contains the results of some original research recently completed by the author on the corrosion pitting of stainless steels.
To investigate the efficacy of Congo red dye (CR) as an inhibitor of the acid corrosion of mild steel and aluminium alloy (AA 1060) and to assess the influence of halide ions on…
Abstract
Purpose
To investigate the efficacy of Congo red dye (CR) as an inhibitor of the acid corrosion of mild steel and aluminium alloy (AA 1060) and to assess the influence of halide ions on the inhibition efficiency.
Design/methodology/approach
Corrosion rates were estimated by monitoring the weight losses of the metal specimen as a function of time at different temperatures. Inhibition efficiency was determined by comparing the corrosion rates in the acid medium in the absence and presence of the additive.
Findings
CR dye reduced the corrosion rates of mild steel and aluminium in the acidic environment. Better inhibition was observed with the mild steel specimen. Protection efficiency was sensitive to inhibitor concentration as well as temperature and generally increased with an increase in CR dye concentration. The halide additives improved the inhibition efficiency in the order KCl < KBr < KI.
Research limitations/implications
The inhibiting effect of CR dye was studied within a fixed concentration range, which could be expanded for further studies. The same applies to the CR+halide systems. Also, the dye structure could be modified by introducing different functional groups, and the effect on inhibition efficiency investigated.
Practical implications
The research findings could find practical application in corrosion control in aqueous acidic environments.
Originality/value
This paper provides new information on the inhibiting characteristics of CR dye under the specified conditions, as a guide to possible applications in metal surface anodizing and surface coatings.
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Jiaxin Li, Zhiyuan Zhu, Zhiwei Li, Yonggang Zhao, Yun Lei, Xuping Su, Changjun Wu and Haoping Peng
Gallic acid is a substance that is widely found in nature. Initially, it was only used as a corrosion inhibitor to retard the rate of corrosion of metals. In recent years, with…
Abstract
Purpose
Gallic acid is a substance that is widely found in nature. Initially, it was only used as a corrosion inhibitor to retard the rate of corrosion of metals. In recent years, with intensive research by scholars, the modification of coatings containing gallic acid has become a hot topic in the field of metal protection. This study aims to summarize the various preparation methods of gallic acid and its research progress in corrosion inhibitors and coatings, as well as related studies using quantum chemical methods to assess the predicted corrosion inhibition effects and to systematically describe the prospects and current status of gallic acid applications in the field of metal corrosion inhibition and protection.
Design/methodology/approach
First, the various methods of preparation of gallic acid in industry are understood. Second, the corrosion inhibition principles and research progress of gallic acid as a metal corrosion inhibitor are presented. Then, the corrosion inhibition principles and research progress of gallic acid involved in the synthesis and modification of various rust conversion coatings, nano-coatings and organic resin coatings are described. After that, studies related to the evaluation and prediction of gallic acid corrosion inhibition on metals by quantum chemical methods are presented. Finally, new research ideas on gallic acid in the field of corrosion inhibition and protection of metals are summarized.
Findings
Gallic acid can be used as a corrosion inhibitor or coating in metal protection.
Research limitations/implications
There is a lack of research on the synergistic improvement of gallic acid and other substances.
Practical implications
The specific application of gallic acid in the field of metal protection was summarized, and the future research focus was put forward.
Originality/value
To the best of the authors’ knowledge, this paper systematically expounds on the research progress of gallic acid in the field of metal protection for the first time and provides new ideas and directions for future research.
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Janaka Chandraguptha Rajaguru, Mike Duke and ChiKit Au
This paper aims to investigate the layer of material deposited on a sample of acrylic resin by electroless nickel plating process. Acrylic resin is a popular material in rapid…
Abstract
Purpose
This paper aims to investigate the layer of material deposited on a sample of acrylic resin by electroless nickel plating process. Acrylic resin is a popular material in rapid prototyping (RP) which uses the additive manufacturing technique to build prototypes for visual inspection, assembly, etc. Metallization of the RP materials can extend application envelop of RP techniques, as they can be used in decorative or functional applications.
Design/methodology/approach
Unlike electroless nickel plating on a metal substrate, the plating process for an acrylic resin substrate is different, as there is no metal ion for the auto-catalytic electroless reaction. Pre-treatment processes are performed on an acrylic resin sample to initiate electroless nickel plating. The morphology, chemical composition and structure of the layer deposited on the sample are examined using scanning electron microscopy, energy-dispersive spectroscopy and X-ray diffraction.
Findings
The investigation shows that a nickel phosphorous alloy layer is plated on to the substrate surface of the acrylic resin sample.
Originality/value
Plating a layer of nickel phosphorous alloy layer on an acrylic resin RP material can widen the application of RP technology. An application of nickel plated acrylic resin sample to rapid tooling for low-volume production plastic parts is presented.
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E.E. Oguzie, A.I. Onuchukwu, P.C. Okafor and E.E. Ebenso
To appraise the inhibiting effect of Ocimum basilicum extract on aluminium corrosion in 2 M HCl and 2 M KOH solutions, respectively, at 30 and 60°C.
Abstract
Purpose
To appraise the inhibiting effect of Ocimum basilicum extract on aluminium corrosion in 2 M HCl and 2 M KOH solutions, respectively, at 30 and 60°C.
Design/methodology/approach
Corrosion rates were determined using the gas‐volumetric technique and the values obtained in absence and presence of extract was used in calculation of the inhibition efficiency. The mechanism of inhibition was estimated from the trend of inhibition efficiency with temperature.
Findings
Ocimum basilicum extract was found to inhibit aluminium corrosion in the acidic and alkaline environments. Inhibition efficiency increased with extract concentration but decreased with rise in temperature, suggesting physical adsorption of the organic matter on the metal surface. These results were corroborated by kinetic and activation parameters for corrosion and adsorption processes evaluated from the experimental data at the temperatures studied. Halide additives synergistically improved the inhibition efficiency of the extract.
Originality/value
This paper provides new information on the possible application of Ocimum basilicum extract as an environmentally friendly corrosion inhibitor. The mixed extract – iodide formulation provides an effective means for retarding aluminium corrosion even in highly aggressive alkaline environments.
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Tereza Hájková and Andrea Kalendova
– This paper aims to synthesise anticorrosion pigments containing molybdenum for paints intended for corrosion protection of metals.
Abstract
Purpose
This paper aims to synthesise anticorrosion pigments containing molybdenum for paints intended for corrosion protection of metals.
Design/methodology/approach
The anticorrosion pigments were prepared by high-temperature solid-state synthesis from the appropriate oxides, carbonates and calcium metasilicate. Stoichiometric molybdates and core-shell molybdates with a non-isometric particle shape containing Ca, Sr, Zn, Mg and Fe were synthesised. The pigments were examined by X-ray diffraction analysis and scanning electron microscopy. Paints based on an epoxy resin and containing the substances at a pigment volume concentration of 10 volume per cent were prepared. The paints were subjected to physico-mechanical tests and to tests in corrosion atmospheres. The corrosion test results were compared to those of the paint with a commercial pigment, which is used in many industrial applications.
Findings
The molybdate structure of each pigment prepared was elucidated. The core-shell molybdates exhibit a non-isometric particle shape. The pigments prepared were found to impart a very good anticorrosion efficiency to the paints. A high anticorrosion efficiency was found with the pigments Fe2(MoO4)3 and Fe2(MoO4)3/CaSiO3 and with Mg and Zn molybdates.
Practical implications
The pigments can be used for the formulation of paints intended for the corrosion protection of metals. The pigments also improve the paints’ physical properties.
Originality/value
The use of the pigments in anticorrosion paints for the protection of metals is new. The benefits include the use and the procedure of synthesis of the anticorrosion pigments which are free from heavy metals and are acceptable from the aspect of environmental protection. Moreover, the core-shell molybdates, whose high efficiency is comparable to that of the stoichiometric molybdates, have lower molybdenum contents.
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M.Y. Zhang, L.Z. Liu, L. Weng, W.W. Cui and K.S. Hui
– The aim of this study was to fabricate polyimide (PI)/Al2O3 composite films via surface modification and ion exchange techniques, and examine their properties.
Abstract
Purpose
The aim of this study was to fabricate polyimide (PI)/Al2O3 composite films via surface modification and ion exchange techniques, and examine their properties.
Design/methodology/approach
The method involves hydrolyzing the PI film double surface layers in an aqueous potassium hydroxide (KOH) solution and incorporating aluminium ions (Al3+) into the hydrolyzed layers of the PI film via subsequent ion exchange, followed by a treatment of the Al3+-loaded PI films with an aqueous ammonia solution, which leads to the formation of Al(OH)3 in the surface-modified layers. After a final thermal annealing treatment in ambient air, the Al(OH)3 decomposes to Al2O3, and forms composite layers on both surfaces of the re-imidized PI film.
Findings
The PI/Al2O3 composite film obtained with a 6 hours of KOH treatment exhibited excellent thermal stability, good mechanical properties and better electric breakdown strength and corona-resistance properties than the pristine PI film.
Practical implications
The method for obtaining the composite films in this paper is worth consideration, but additional research will be needed. Furthermore, this method is of general importance for the fabrication of composite PI films with tailored properties.
Originality/value
This study showed that surface modification and ion-exchange techniques are powerful methodologies for the fabrication of PI/Al2O3 composite films.
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A.U. Chaudhry, Vikas Mittal, M.I. Hashmi and Brajendra Mishra
Inorganic oxide addition can be synergistically beneficial in organic coatings if it can impart anti-corrosion properties and also act as an additive to enhance physical and/or…
Abstract
Purpose
Inorganic oxide addition can be synergistically beneficial in organic coatings if it can impart anti-corrosion properties and also act as an additive to enhance physical and/or chemical properties. The aim of this study was to evaluate the anti-corrosion benefits of nano nickel zinc ferrite (NZF) in the polymer film.
Design/methodology/approach
The time-dependent anti-corrosion ability of NZF (0.12-1.0 per cent w/w NZF/binder), applied on API 5L X-80 carbon steel, was characterized by electrochemical techniques such as open circuit potential, electrochemical impedance spectroscopy, linear polarization resistance and potentiodynamic. Characterization of corrosion layer was done by removing coatings after 216 h of immersion in 3.5 per cent w/v NaCl. Optical microscopy, field emission scanning electron microscopy and X-ray diffraction techniques were used to characterize the corroded surface.
Findings
Corrosion measurements confirm the electrochemical activity by metallic cations on the steel surface during corrosion process which results in improvement of anti-corrosion properties of steel. Moreover, surface techniques show compact corrosion layer coatings and presence of different metallic oxide phases for nanocomposite coatings.
Originality/value
The suggested protection mechanism was explained by the leaching and precipitation of metallic ion on the corroded surface which in turn slowed down the corrosion activity. Furthermore, improvement in barrier properties of rubber-based coatings was confirmed by the enhanced pore resistance. This work indicates that along with a wide range of applications of NZF, anti-corrosion properties can be taken as an addition.
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S. Muralidharan, P. Chandrakumari, K. Madhavan, T. Vasudevan and S. Venkatakrishna Iyer
Introduction Amines have been known for a number of years as effective corrosion inhibitors. Their efficiency is attributed to the presence of the nitrogen atom acting as the…
Abstract
Introduction Amines have been known for a number of years as effective corrosion inhibitors. Their efficiency is attributed to the presence of the nitrogen atom acting as the active centre for the adsorption of organic molecules on the metal surface. Several aliphatic and aromatic amines have been reported to serve as effective corrosion inhibitors for iron and steel in acidic solutions. The nitrogen‐containing corrosion inhibitor exhibited a very good performance in hydrochloric acid, but very little effect in sulphuric acid. Hence a study of the mechanism by which the corrosion rate is reduced when these organic compounds are added to solutions is of interest. In this study the inhibition of corrosion of mild steel in HCl and H2SO4 has been studied using different electrochemical techniques. Results are reported and discussed.
Abstract
Purpose
This study/paper aims to the authors applied low “Si” ions dose over cp-Ti-2, and the potent dose level was optimized for adequate corrosion resistance and effective proliferation of stem cells.
Design/methodology/approach
The cp-Ti surface was modified by silicon (Si) ions beam at 0.5 MeV in a Pelletron accelerator. Three different ion doses were applied to the polished samples, and the surface was characterized by XRD and AFM analysis.
Findings
At moderate “Si” ion dose (6.54 × 1012 ions-cm−2), the potential shifted to a noble value. The small “icorr” (1.22 µA.cm−2) and relatively large charge transfer resistance (43.548 kΩ-cm2) in the ringer‘s lactate solution was confirmed through Potentiodynamic polarization and impedance spectroscopy analysis. Compared to cp-Ti and other doses, this dose level also provided the effective proliferation of mesenchymal stem cells.
Originality/value
The dosage levels used were different to previous work and provided the effective proliferation of mesenchymal stem cells.
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