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Ahmed N.M.,National Research Center of Egypt | Abdel-Fatah H.T.M.,Egyptian Electricity Holding Company | Youssef E.A.,National Research Center of Egypt
Progress in Organic Coatings | Year: 2012

Core-shell theory presents a new easy route to obtain high performance, and eco-friendly anticorrosive pigments with concomitant savings. This theory is based on depositing a surface layer of expensive efficient anticorrosive pigment on a cheap extender expressing the bulk. The combination of both core and shell compounds led to the production of new pigments with improved properties different from each of its individual components; and consequently these improved properties lead to change in the efficiency of protection properties of paint films containing these new pigments. The objective of the present work is to prepare a new ecologically friendly inorganic pigment, based on the solid-solid interaction of cobalt oxide with zinc oxide on surface of kaolin. The species of CoO and ZnO are susceptible to react with alumina part in the kaolin forming Zn·Co aluminate/kaolin. The new pigment will be incorporated in medium oil alkyd-based paints. The effect of cobalt aluminate/kaolin, zinc aluminate/kaolin individually and zinc·cobalt aluminate/kaolin on the protection performance of paint films containing them will be compared and studied. Another comparison will be held out between films containing nano- and micro-zinc·cobalt aluminate/kaolin to determine the best among the prepared pigments for better corrosion prevention. The comparison will be done using accelerated laboratory test for 28 days in artificial sea water and electrochemical impedance spectroscopy. The results revealed that nano-pigments and pigments containing higher concentration of zinc were the best in protecting steel substrates. © 2011 Elsevier B.V. All rights reserved.

Ahmed N.M.,National Research Center of Egypt | Emira H.S.,National Research Center of Egypt | Tawfik H.M.,Egyptian Electricity Holding Company
Pigment and Resin Technology | Year: 2013

Purpose - Ion-exchange clays containing sodium such as bentonite and montmorillonite have the ability to exchange their cations. Few studies conducted with this type of ion-exchange pigments are not conclusive about their anticorrosive efficiency. The present research aims to address the study on the anticorrosive efficiency of this type of pigments in chlorinated rubber paints. Sodium-bentonite was exchanged with Zn, Sr and Zn-Sr to be applied on low carbon steel specimens and study the anticorrosive performances of these new ion-exchanged bentonites (IEBs) in anticorrosive paint formulations. Design/methodology/approach - The new pigments were characterised using scanning electron microscopy (SEM) and X-ray fluorescence (XRF) to determine the CEC (cation exchange capacity) of the different exchanged cations. Evaluation of the ion-exchanged and Na-bentonite pigments using international standard testing methods (ASTM) was estimated. Paint systems manufactured with these ion-exchange pigments have been subjected to adhesion, accelerated corrosion laboratory tests, and EIS in order to assess their anticorrosive behaviour. Findings - The results of this work revealed that the ion-exchange bentonite (IEBs) pigments showed high anticorrosive performance that can be arranged as follows: Sr-bentonite was better than Zn-Bentonite and both were better than the double Zn-Sr-bentonite indicating an antagonism behaviour between the two cations when present together. Practical implications - These pigments can be applied in other polymer composites, e.g. rubber and plastics as reinforcing agent and fillers. Originality/value - These prepared pigments are environmentally friendly pigments which impart high anticorrosive behaviour to paint films with great economic savings. © 2013 Emerald Group Publishing Limited. All rights reserved.

Fouda A.S.,Mansoura University | Tawfik H.,Egyptian Electricity Holding Company | Abdallah N.M.,Mansoura University | Ahmd A.M.,Alex University
International Journal of Electrochemical Science | Year: 2013

Some indole derivatives are investigated as corrosion inhibitors for nickel in 0.5 M HCl solution using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. A significant decrease in the corrosion rate of nickel was observed in the presence of investigated indole derivatives. Potentiodynamic polarization curves revealed that these inhibitors acted as mixed-type inhibitors, affecting both cathodic and anodic corrosion processes. The adsorption of the inhibitors on nickel surface in 0.5 M HCl was found to follow Frumkin adsorption isotherm. Thermodynamic adsorption parameters (Kads, δG°ads) of investigated inhibitors were calculated from the linear form of Frumkin adsorption isotherm. Activation parameters of the corrosion process were calculated and discussed. EIS was used to investigate the mechanism of corrosion inhibition. Correlation between the inhibition efficiency and the structure of these inhibitors are presented.

Abdel-Fatah H.T.M.,Egyptian Electricity Holding Company
Anti-Corrosion Methods and Materials | Year: 2012

Purpose: The purpose of this paper is to carry out laboratory studies of the inhibition effect of tyrosine (Tyr) on the corrosion of low chromium alloy steel (ASTM A213 grade T22) in 7 wt percent sulfamic acid solutions. Design/methodology/approach: The corrosion inhibitive effect of Tyr was investigated using electrochemical impedance spectroscopy (EIS) and the new technique electrochemical frequency modulation (EFM). Findings: It was found that the inhibition efficiency increased with increasing inhibitor concentration, while a decrease was detected with the rise of temperature and stirring speed. The corrosion inhibition is due to physical adsorption of Tyr on the steel surface. Adsorption of the inhibitor molecule, onto the steel surface follows the Temkin's adsorption isotherm. Originality/value: The obtained results from both methods (EIS and EFM) at different experimental conditions were in high agreement and almost similar. This is an indication that the EFM technique can be used efficiently for monitoring the corrosion inhibition under the studied conditions. © Emerald Group Publishing Limited.

Gabr W.I.M.,Egyptian Electricity Holding Company
2010 IEEE International Conference on Information and Automation, ICIA 2010 | Year: 2010

The paper presents further development of the Arithmetic Fuzzy Logic-based Representation using the notion of normalized fuzzy matrices. The investigation is based on the dual cell representation, expressed by replacing each parameter with a pair of parentheses, the first is the actual value and the second is corresponding fuzzy level. The analogy between the proposed Arithmetic Fuzzy Logic-based Representation technique and the Conventional Fuzzy Theory are derived for various cases of operations of addition, subtraction, multiplication and division. It is shown that the suggested approach is identical to that of the Conventional Fuzzy Theory for addition operations and gives average weighted fuzziness interval results of the subtraction operations. Moreover, it yields similar results of multiplication and division operations after ignoring the second order relative variations terms. However, the suggested approach offers additional advantages of linearity, reversibility, simplicity, and applicability. Application of the proposed Arithmetic Fuzzy Logic-based Representation to a Case Study of a fuzzy PERT problem is presented to demonstrate the efficacy of the proposed technique. Finally, it is pointed out that, for similar situations, the solution of the Conventional Fuzzy Theory is very cumbersome and is completely impractical for high dimensional systems. ©2010 IEEE.

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