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Benabdellah M.,University Mohammed Premier | Khaled K.F.,Electrochemistry Research Laboratory | Khaled K.F.,Taif University | Hammouti B.,University Mohammed Premier
Materials Chemistry and Physics | Year: 2010

The corrosion behaviour of steel at various concentrations of perchloric acid was studied by weight loss method in temperature range from 298 to 323 K. Results obtained show that corrosiveness of acid increases with its concentration and temperature. The logarithm of corrosion rate was plotted against the acid concentration and values of Hammett Ho and Strehlow Ro(H) acidity functions. The activation energies, enthalpies and entropies of the corrosion process of steel were also determined and fitted against Ro(H). © 2009 Elsevier B.V. All rights reserved.


Hosseini M.G.,Electrochemistry Research Laboratory | Abdolmaleki M.,University of Tehran | Sadjadi S.A.S.,University of Tehran
Protection of Metals and Physical Chemistry of Surfaces | Year: 2010

Electrodeposition of Ni-W-B alloys from plating baths containing tartrate in the absence of ammonia is studied. Detailed studies on the effects of bath temperature, pH, cathode current density and plating time have led to optimum operational conditions for obtaining satisfactory alloy deposits. The operational conditions for deposition the alloy with high hardness are; current density 30 mA cm-2, pH 6.0 and bath temperature of 60°C. The results have shown that the adherence of Ni-W-B is better than the Ni and Chromium on Cu substrate. It adheres to Cu substrates better than electrodeposited Ni and chromium. The morphology of the deposits was studied by SEM and the analysis of composition performed by EDX and inductively coupled plasma (ICP). The as-deposited alloy contained 21.66 wt % W and the highest cathode current efficiency for deposition of the alloy was about 38%. The deposit obtained under these conditions had an amorphous character with a hardness of about 800 H V, which is comparable to the hardness of chromium, occurred at a heat treatment temperature of 400°C. When heat treated up to this temperature, the initial metastable structure decomposed into fine particles of Ni4W in a nickel solid solution. © Pleiades Publishing, Ltd., 2010.


Bhata R.,Electrochemistry Research Laboratory | Bhat K U.,National Institute of Technology Karnataka | Hegdea A.C.,Electrochemistry Research Laboratory
Protection of Metals and Physical Chemistry of Surfaces | Year: 2011

Sulfate bath having ZnSO4 ̇ 7H2O, Fe 2(SO4)3 ̇ H2O and thiamine hydrochloride (THC) and cit- ric acid (CA) in combination, represented as (THC + CA) was optimized for deposition of bright Zn-Fe alloy coating on mild steel. Bath constituents and operating parameters were optimized by standard Hull cell method, for peak performance of the coating against corrosion. The effect of current density (c.d.), pH and temperature on deposit characters, such as corrosion resistance, hardness and glossiness were studied and dis- cussed. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods were used to assess the corrosion behaviors. Surface morphology, and composition of the coatings were examined using Scanning Electron Microscopy (SEM), interfaced with EDXA facility, respectively. The Zn-Fe alloy, with intense peaks corresponding to Zn(100) and Zn(101) phases, showed highest corrosion resistance, evi- denced by X-ray diffraction (XRD) study. A new and cheap sulfate bath, for bright Zn-Fe alloy coating on mild steel has been proposed, and results are discussed. © Pleiades Publishing, Ltd., 2011.


Nasibi M.,National Iranian Oil Company | Nasibi M.,Petroleum University of Technology of Iran | Rafiee E.,National Iranian Oil Company | Rashed G.,National Iranian Oil Company | And 2 more authors.
Journal of Dispersion Science and Technology | Year: 2013

Inhibitory action of safflower (Carthamus tinctorius) extract (SE) was investigated in hydrochloric acid solution through electrochemical (polarization, EIS), and surface analysis (optical microscopy/atomic force microscopy (AFM)/scanning electron microscopy (SEM)/energy dispersive spectroscopy (EDS)) techniques. In addition, Inhibition efficiency was predicted by neural network (NN) modeling in elevated temperatures and different acid concentrations. The thermodynamic adsorption parameters propose that this inhibitor retard both cathodic and anodic processes through physical adsorption and blocking the active corrosion sites. Surface analysis techniques confirm the inhibitor adsorption on the metal surface, which is in accordance with the variation of apparent activation energy of corrosion. Finally, inhibition efficiency is discussed in terms of protective film formation. © 2013 Copyright Taylor and Francis Group, LLC.


Yogesha S.,National Institute of Technology Karnataka | Udaya Bhat K.,National Institute of Technology Karnataka | Chitharanjan Hegde A.,National Institute of Technology Karnataka | Chitharanjan Hegde A.,Electrochemistry Research Laboratory
Synthesis and Reactivity in Inorganic, Metal-Organic and Nano-Metal Chemistry | Year: 2011

Electrodeposition of Zn-Co alloy onmild steel has been studied, using thiamine hydrochloride (THC) as an additive. The effect of current density on deposit characters, such as chemical composition, thickness, hardness, phase structure, and surface morphology has been investigated. The electrochemical corrosion study revealed that the coating with 1.69 wt. % Co, deposited at 3.0 A dm-2 exhibited the best corrosion stability. Scanning electron microscopy (SEM), energy depressive spectroscopy (EDX), and X-ray diffraction (XRD) analyses were used to study the surface morphology, chemical composition, and phase structure of the coatings. The results were discussed focusing the effect of THC on coating characters. Copyright © Taylor & Francis Group, LLC.


Agarwal S.,Electrochemistry Research Laboratory | Kalpana S.,Electrochemistry Research Laboratory
Rasayan Journal of Chemistry | Year: 2011

Mixed ligand systems (carboxymethylmercaptosuccinate - alaninate, carboxymethyl-mercaptosuccinate-aspartate, carboxymethylmercaptosuccinate- glutaminate, carboxymethylmer-captosuccinate-valinate, with Cd(II), Pb(II) and T1(I) in aqueous-non aqueous (3:2 v/v aqueous ethanol) media at constant ionic strength (KNO 3 μ = 1.0 M), pH (6.2 ± 0.02) and temperature (303 ± 2K) have been studied polarographically. Thymol (0.01%) was used as wave maxima suppressor. It was shown that only one mixed ligand entity (M AiXj) is formed in all cases of carboxymethylmercaptosuccinate alaninate/ aspartate/ glutaminate/ valinate systems where 'i' and j are one for all Cd(II) Pb(II), and T1(I) metal complexes formed. A and X are carboxymethylmercaptosuccinate and alaninate/ aspartate/ glutaminate/ valinate/ respectively. Compositions and stability constants of single mixed ligand species formed have been evaluated employing Souchay and Faucherre's method. © 2011 RASAYAN.


Ashassi-Sorkhabi H.,Electrochemistry Research Laboratory | Bagheri R.,Electrochemistry Research Laboratory | Rezaei-Moghadam B.,Electrochemistry Research Laboratory
Journal of Applied Polymer Science | Year: 2014

The polypyrrole (PPy) and polypyrrole-Au (PPy-Au) nanocomposite films have been sonoelectrochemically synthesized on St-12 steel electrodes using the galvanostatic technique. Experimental design according to the Taguchi method has been applied to optimize the factors on the synthesis of PPy-Au nanocomposite coating. Three factors were used to design an orthogonal array L9: Synthesis time (t), Current density (I), and Concentration of HAuCl4 (C). The synthesized Au nanoparticles during polymerization were characterized by Ultraviolet-visible (UV-visible) spectroscopy. Characterization of the surfaces was done by scanning electron microscope (SEM), energy dispersive X-ray spectrum (EDX), and atomic force microscope (AFM). The scanning electron microscopy (SEM) image of PPy shows a smooth surface while PPy-Au nanocomposite film has a compact morphology. Moreover, energy dispersive X-ray spectrum (EDX) is evidence for the incorporation of Au nanoparticles. The corrosion protection of coatings was investigated by open circuit potential (OCP) time trends, potentiodynamic polarization technique, and electrochemical impedance spectroscopy (EIS) in a NaCl 3.5% solution. © 2014 Wiley Periodicals, Inc.

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