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Article
Publication date: 27 June 2008

A. Kalendová and D. Veselý

The purpose of this paper is to synthesize anticorrosion pigments ZnFe2O4 from diverse raw materials of various shapes and size of primary particles.

Abstract

Purpose

The purpose of this paper is to synthesize anticorrosion pigments ZnFe2O4 from diverse raw materials of various shapes and size of primary particles.

Design/methodology/approach

Anticorrosion pigments were synthesized through a high‐temperature process during a solid phase. Zinc ferrites were prepared from hematite (α‐Fe2O3), goethite (α‐FeO.OH), magnetite (Fe3O4), and specularite (Fe2O3) entering into reaction with zinc oxide at temperatures ranging from 600 up to 1,100°C. The nature of the initial raw material, primarily the shape of its particles, affects the shape of the particles of the synthesized zinc ferrite. The formulated zinc ferrites had a rod‐shape, lamellar, and/or isometric shape. The shape of the particles of synthesized zinc ferrites was studied with regard to its effects on the mechanical and corrosion resistance of organic coatings. The obtained pigments were characterized by means of X‐ray diffraction analysis and scanning electron microscopy. The synthesized anticorrosion pigments were used to prepare epoxy coatings and water‐borne styrene‐acrylate coatings that were subjected to post‐application tests for physical‐mechanical properties and anticorrosion properties.

Findings

The shape of the particles was identified in the synthesized pigments. X‐ray diffraction analysis revealed the degree of precipitation and lattice parameters. All of the synthesized pigments had good anticorrosion efficiency in an epoxy and in styrene‐acrylate coatings. Compared with a commercially used anticorrosion pigment, their protective power in coatings was demonstrably stronger.

Practical implications

The synthesized pigments can be used conveniently in coatings protecting metal bases against corrosion.

Originality/value

The synthesis of zinc ferrites with different particle shapes for applications in anticorrosion coatings provides a new way of protecting metals against corrosion. Of benefit is the fact that the synthesized pigments do not contain any environmentally harmful substances.

Details

Anti-Corrosion Methods and Materials, vol. 55 no. 4
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 1 August 2002

I. Kotzamanidi, A. Anastassiadis, L. Filippaki, S.E. Filippakis, P. Vassiliou and Em. Sarris

The application of hydrogen plasma on corroded steel and excavated iron artefacts has been studied. Transformations of the corrosion layer due to the plasma effect were…

Abstract

The application of hydrogen plasma on corroded steel and excavated iron artefacts has been studied. Transformations of the corrosion layer due to the plasma effect were investigated by means of X‐ray diffraction analysis. The reduction of iron oxides to the stable iron oxide, magnetite, was observed for all the samples. In the case of excavated objects, the reduction to magnetite did not occur throughout the whole of the bulk of the oxides, as it does (for example) in the case of steel corroded in the laboratory. Nevertheless, excavated objects, in which a metallic core remained, were stabilised against subsequent corrosion. However, objects that are completely oxidised must be treated carefully, because treatment may result in the formation of a brittle outer layer, and there is a risk of disintegration of such items, if treated using the plasma conditioning and restoration procedure.

Details

Anti-Corrosion Methods and Materials, vol. 49 no. 4
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 1 July 1966

C.W. Tuck, M. Odgers and K. Sachs

The work described in this paper is part of a current programme that has two objects: (1) to investigate further the reasons for the different scaling behaviour of steel…

Abstract

The work described in this paper is part of a current programme that has two objects: (1) to investigate further the reasons for the different scaling behaviour of steel in steam and carbon dioxide, although these gases have similar oxygen potentials; (2) to provide background information for an investigation into the effect of variations in re‐heating furnace atmospheres upon scaling and scale adhesion.

Details

Anti-Corrosion Methods and Materials, vol. 13 no. 7
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 1 November 1969

C.W. Tuck

One of the problems in the production of narrow hot‐rolled mild steel strip is the formation, at the edges of the strip, of scale that can be extremely resistant to…

Abstract

One of the problems in the production of narrow hot‐rolled mild steel strip is the formation, at the edges of the strip, of scale that can be extremely resistant to pickling; This extreme resistance to pickling of ‘hard edge scale’ sometimes requires repickling of a considerable percentage of coils with consequent loss of production and deterioration of surface finish. The paper considers in detail the correlation between the microstructure of scale on the strip and its pickling behaviour. It is shown that certain characteristics of the microstructure, peculiar to ‘hard edge scale’, i.e. increased thickness, the presence of a primary magnetite layer, greater degree of wüstite transformation and the nature and presence of haematite, can be suppressed to a greater or lesser degree by variations in the cooling cycle. It is considered that no single one of these structural differences between hard edge scale and that which is removed readily from the centre of the strip would, by itself, interfere with pickling, but when these characteristics occur together repickling is made necessary. The above observations and conclusions are supported by results obtained from pickling tests carried out in the laboratory on samples taken from a wide range of coils.

Details

Anti-Corrosion Methods and Materials, vol. 16 no. 11
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 2 May 2017

Agustín Sánchez-Deza, David M. Bastidas, Angel La Iglesia and Jose-María Bastidas

The purpose of this study is to use thermodynamic data to estimate the pressure exerted by the crystallization of iron oxyhydroxides following the equation proposed by…

Abstract

Purpose

The purpose of this study is to use thermodynamic data to estimate the pressure exerted by the crystallization of iron oxyhydroxides following the equation proposed by Correns and Steinborn.

Design/methodology/approach

Standard free energy and molar volume data have been considered for goethite, lepidocrocite, magnetite and hematite, which are described in the literature as the most commonly found mineral phase rust constituents.

Findings

The studied mineral phases generate higher to lower crystallization pressure values in the following order: goethite > lepidocrocite > hematite > magnetite. The crystallization pressures calculated for these phases are in the 32-350 MPa range, which is higher than the tensile strength of concrete (of the order of 0.2-10 MPa) and thus leads to failure of the cover concrete.

Originality/value

The aim of this paper is to shed light on this issue by calculating the stresses generated by the crystallization of iron oxide from a supersaturated solution using thermodynamic data. A deliberately simplistic method was proposed, taking as reference the Correns–Steinborn model (Correns and Steinborn, 1939; Correns, 1949). The crystalline phases considered in this paper are those most commonly found in the literature as rust constituents, that is, goethite (α-FeOOH), lepidocrocite (γ-FeOOH), magnetite (Fe3O4) and hematite (α-Fe2O3). The FeO synthetic phase was also included as a reference.

Details

Anti-Corrosion Methods and Materials, vol. 64 no. 3
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 12 June 2017

Meysam Amini, Esmaeil GhasemiKafrudi, Mohammad Reza Habibi, Azin Ahmadi and Akram HosseinNia

Due to the extensive industrial applications of stagnation flow problems, the present work aims to investigate the magnetohydrodynamics (MHD) flow and heat transfer of a…

Abstract

Purpose

Due to the extensive industrial applications of stagnation flow problems, the present work aims to investigate the magnetohydrodynamics (MHD) flow and heat transfer of a magnetite nanofluid (here Fe3O4–water nanofluid) impinging a flat porous plate under the effects of a non-uniform magnetic field and chemical reaction with variable reaction rate.

Design/methodology/approach

Similarity transformations are applied to reduce the governing partial differential equations with boundary conditions into a system of ordinary differential equations over a semi-infinite domain. The modified fourth-order Runge–Kutta method with the shooting technique which is developed for unbounded domains is conducted to give approximate solutions of the problem, which are then verified by results of other researchers, showing very good agreements.

Findings

The effects of the volume fraction of nanoparticles, permeability, magnetic field, chemical reaction and Schmidt number on velocity, temperature and concentration fields are examined and graphically illustrated. It was found that fluid velocity and temperature fields are affected strongly by the types of nanoparticles. Moreover, magnetic field and radiation have strong effects on velocity and temperature fields, fluid velocity increases and thickness of the velocity boundary layer decreases as magnetic parameter M increases. The results also showed that the thickness of the concentration boundary layer decreases with an increase in the Schmidt number, as well as an increase in the chemical reaction coefficient.

Research limitations/implications

The thermophysical properties of the magnetite nanofluid (Fe3O4–water nanofluid) in different conditions should be checked.

Practical implications

Stagnation flow of viscous fluid is important due to its vast industrial applications, such as the flows over the tips of rockets, aircrafts, submarines and oil ships. Moreover, nanofluid, a liquid containing a dispersion of sub-micronic solid particles (nanoparticles) with typical length of the order of 1-50 nm, showed abnormal convective heat transfer enhancement, which is remarkable.

Originality/value

The major novelty of the present work corresponds to utilization of a magnetite nanofluid (Fe3O4–water nanofluid) in a stagnation flow influenced by chemical reaction and magnetic field. It should be noted that in addition to a variable chemical reaction, the permeability is non-uniform, while the imposed magnetic field also varies along the sheet. These, all, make the present work rather original.

Details

World Journal of Engineering, vol. 14 no. 3
Type: Research Article
ISSN: 1708-5284

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Article
Publication date: 18 January 2019

Mohamed Kezzar, Nawel Boumaiza, Ismail Tabet and Nourreddine Nafir

This paper aims to traitted the combined effects of ferromagnetic particles and magnetic field on mixed convection in the Falkner Skan equation using analytical solution…

Abstract

Purpose

This paper aims to traitted the combined effects of ferromagnetic particles and magnetic field on mixed convection in the Falkner Skan equation using analytical solution by the Duan–Rach method.

Design/methodology/approach

Visualization and grouping of effects of various physical parameters such as electrical conductivity of ferro-particles (electrical conductivity calculated using Maxwell model), ferro fluid volume fraction for Magnetite-Fe3O4-water and magnetic field represented by the Hartmann number in a set of third- and second-order nonlinear coupled ordinary differential equations. This set of equations is analytically processed using the Duan–Rach Approach (DRA).

Findings

Obtained DRA results are validated using a numerical solution (Runge–Kutta–Fehlberg-based shooting method). The main objective of this research is to analyze the influence of physical parameters, in particular electrical conductivity, Ferrofluid volume fraction in the case of Magnetite-Fe3O4-water, in addition to the types of solid nanoparticles and Hartmann number on dynamic and thermal distributions (velocity/temperature). Results of the comparison between the numerical solution (Runge–Kutta–Fehlberg-based shooting method) and the analytical solution (DRA) show that the DRA data are in good agreement with numerical data and available literature.

Originality/value

The study uses Runge–Kutta–Fehlberg-based shooting method) and the analytical solution (DRA) to investigate the effect of mixed convection, in the presence of Ferro particles (Magnetite-Fe3O4) in a basic fluid (water for example) and subjected to an external magnetic field on the Falkner–Skan system.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 29 no. 2
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 11 June 2018

Somrerk Chandra-ambhorn, Sermsak Srihirun and Thamrongsin Siripongsakul

The purpose of this study is to investigate the aesthetic blackening coating formed by a hydrothermal process, focusing on the formation of magnetite and the oxide…

Abstract

Purpose

The purpose of this study is to investigate the aesthetic blackening coating formed by a hydrothermal process, focusing on the formation of magnetite and the oxide adhesion for improving the corrosion resistance of the steel.

Design/methodology/approach

The aesthetic black coating was applied on AISI 4140 steel using a hydrothermal process with a non-toxic solution consisted of ferrous sulphate hydrate (FeSO4·7H2O), sodium hydroxide (NaOH) and hydrazine hydrate (N2H4·H2O). Upon process parameters temperature and time, the morphology of the coatings and oxidation kinetics were investigated by using scanning electron microscopy and X-ray diffraction (XRD) analysis. Furthermore, the samples with coatings were subjected to the adhesion test using a tensile testing machine equipped with a charge-coupled device (CCD) camera.

Findings

From the formation parameters due to temperature and time for the conversion coatings, it was found that the oxidation kinetics had special characteristics which were in accordance with a linear rate law and Arrhenius relation. For the samples blackened, the XRD analysis results revealed that the magnetite was successfully formed on the surface of the steel. On the other hand, increasing the blackening temperature worsened the scale adhesion as observed by the lower strain provoking the first spallation and the higher sensitivity of the oxide to spall out with the imposed strain.

Originality/value

The effects of parameters of the formation of conversion coatings were investigated to understand the kinetics of the coatings. Furthermore, a tensile adhesion test using a CCD camera was applied to evaluate the adhesion between the native oxide formed by conversion coating.

Details

Anti-Corrosion Methods and Materials, vol. 65 no. 4
Type: Research Article
ISSN: 0003-5599

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Book part
Publication date: 19 May 2009

Michael Lounsbury, Christopher Kelty, Cafer T. Yavuz and Vicki L. Colvin

In the wake of growing pressures to make scholarly knowledge commercially relevant via translation into intellectual property, various techno-scientific communities have…

Abstract

In the wake of growing pressures to make scholarly knowledge commercially relevant via translation into intellectual property, various techno-scientific communities have mobilized to create open access/open source experiments. These efforts are based on the ideas and success of free and open source software, and generally try to exploit two salient features: increased openness and circulation, and distributed collective innovation. Transferring these ideas from software to science often involves unforeseen challenges, one of which is that these movements can be deemed, often incorrectly, as heretical by university administrators and technology transfer officers who valorize metrics such as number of patents filed and granted, spin-off companies created, and revenue generated. In this paper, we discuss nascent efforts to foster an open source movement in nanotechnology and provide an illustrative case of an arsenic removal invention. We discuss challenges facing the open source nano movement that include making a technology widely accessible and the associated politics of metrics.

Details

Measuring the Social Value of Innovation: A Link in the University Technology Transfer and Entrepreneurship Equation
Type: Book
ISBN: 978-1-84855-467-2

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Article
Publication date: 2 March 2015

Mariela Rendón Belmonte, Miguel Martínez Madrid, José Trinidad Pérez-Quiroz, Benjamín Valdez Salas, Erick A. Juarez-Arellano and Miguel Schorr

The purpose of this paper was to characterize the surface of steel reinforcement of concrete under cathodic protection (CP), submerged in seawater, to understand the…

Abstract

Purpose

The purpose of this paper was to characterize the surface of steel reinforcement of concrete under cathodic protection (CP), submerged in seawater, to understand the surface changes due to the application of CP and their consequences on cathodic current requirements.

Design/methodology/approach

Reinforced concrete specimens with applied CP were immersed in natural seawater. The experimental methodology included monitoring of corrosion potential (Ecorr); measurement of galvanic current (Igalv), protection potential (Eprotection) and the depolarization potential of steel during the time of exposure; and electrochemical impedance spectroscopy (EIS). The chemical composition of the steel surface was assessed using X-ray diffraction (XRD).

Findings

The application of CP leads to the formation of a deposit on the steel surface that according to XRD results, Pourbaix diagram and physical characteristics, is a protective oxide: magnetite (Fe3O4). This oxide causes a decrease in the corrosion rate and requires application of the protection current. It was found that the surface remained protected even after eight days when the CP system was interrupted.

Research limitations/implications

It is necessary to carry out analysis of the chemical composition of deposits formed on the steel surface, perhaps using X-ray photoelectron spectroscopy, Mössbauer, to verify the presence of the magnetite.

Practical implications

Determination of the main cause of the decrease in current required for protection and deposit formation conditions will enable the design of a CP system to be optimized and economized. At present, the CP design considers only a constant current value for the duration of the protection time.

Originality/value

CP is a technique that has proven effective for the protection of metal structures. However, little attention has been devoted to the surface changes that occur under applied CP and their impact on the electrochemical behavior of the system. This paper describes the phenomena produced at the metal surface and determines kinetic parameters and their consequences on the CP behavior.

Details

Anti-Corrosion Methods and Materials, vol. 62 no. 2
Type: Research Article
ISSN: 0003-5599

Keywords

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