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Evaluation of cathodic disbondment of epoxy coating containing azole compounds
M. Mahdavian,R. Naderi,M. Peighambari,M. Hamdipour,S.A. Haddadi 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.21 No.1
Cathodic disbonding of the epoxy coatings on the mild steel was evaluated in 3.5% NaCl solution, wherebenzimidazole, benzothiazole and benzotriazole were used as additives in the coatings. Also, theelectrochemical behavior of coatings delaminating in NaCl solution from a small artificial defect and thebare mild steel samples in the 3.5% NaCl solution containing the azole compounds was evaluated byelectrochemical impedance spectroscopy at cathodic polarization condition. Results showed that theazole compounds were not immobilized in the coating as they could leach out and act as cathodicinhibitor at defect site and disbonding front.
Enhancement of silane coating protective performance by using a polydimethylsiloxane additive
M. Mahdavian,B. Ramezanzadeh,M. Akbarian,M. Ramezanzadeh,P. Kardar,E. Alibakhshi,S. Farashi 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.55 No.-
This work intends to study the effect of a polydimethylsiloxane additive on the protection performance of a hybrid silane coating on mild steel. Electrochemical impedance spectroscopy, polarization and electrochemical noise measurements and salt spray showed an increase in corrosion resistance of the silane coating in the presence of the additive. Silane films were examined by FTIR, water droplet contact angle, Vickers hardness and SEM. Results showed decrease in crosslinking density in the presence of the additive. Superior corrosion protection in the presence of additive was attributed to the enhanced hydrophobic character and flexibility of the coating.
Application of Computer Aided Upper Bound Method in Forging and Extrusion Processes
Liu, Gary,Mahdavian, S . M . 대한금속재료학회(대한금속학회) 1998 METALS AND MATERIALS International Vol.4 No.4
This paper presents the development of a Computer Aided Upper Bound software i~or the plain-strain upset forging, and closed impression die processes. The upper bound method is applied by providing the number of plastic sections (triangles). friction conditions of the tool surfaces, and geometry parameters as inputs to a predefined tool and workpiece configuration. The program calculates the funning pressure and provides the upper bound metal flow field and hodograph as outputs. The forming pressure is calculated by an upper bounding algorithm which can be unproved by increasing the number of plastic sections. The differences in tool and workpiece surface friction coefficients and variation of die angles can be considered in order to optimize the forming process.
Theoretical Studies of Hydrogen Bond Interactions in Fluoroacetic Acid Dimer
Alireza Najafi Chermahini,Mohsen Mahdavian,Abbas Teimouri 대한화학회 2010 Bulletin of the Korean Chemical Society Vol.31 No.4
Ab initio and density functional theory methods have been employed to study all theoretically possible conformers of fluoroacetic acid. Molecular geometries and energetic of cis and trans monomers and cis dimers in gaseous phase have been obtained using HF, B3LYP and MP2 levels of theory, implementing 6-311++G(d,p) basis set. It was found that cis rotamers are more stable. In addition, it was found that in comparison with acetic acid the strength of hydrogen bonding in fluoroacetic acid decreased. The infrared spectrum frequencies and the vibrational frequency shifts are reported. Natural population and atom in molecule analysis performed to predict electrostatic interactions in the cyclic H-bonded complexes and charges. The proton transfer reaction is studied and activation energy is compared with acetic acid proton transfer reaction.
Theoretical Studies of Hydrogen Bond Interactions in Fluoroacetic Acid Dimer
Chermahini, Alireza Najafi,Mahdavian, Mohsen,Teimouri, Abbas Korean Chemical Society 2010 Bulletin of the Korean Chemical Society Vol.31 No.4
Ab initio and density functional theory methods have been employed to study all theoretically possible conformers of fluoroacetic acid. Molecular geometries and energetic of cis and trans monomers and cis dimers in gaseous phase have been obtained using HF, B3LYP and MP2 levels of theory, implementing 6-311++G(d,p) basis set. It was found that cis rotamers are more stable. In addition, it was found that in comparison with acetic acid the strength of hydrogen bonding in fluoroacetic acid decreased. The infrared spectrum frequencies and the vibrational frequency shifts are reported. Natural population and atom in molecule analysis performed to predict electrostatic interactions in the cyclic H-bonded complexes and charges. The proton transfer reaction is studied and activation energy is compared with acetic acid proton transfer reaction.
Corrosion inhibition properties of a green hybrid pigment based on Pr-Urtica Dioica plant extract
M. Motamedi,B. Ramezanzadeh,M. Mahdavian 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.66 No.-
The main aim of this research is studying the corrosion inhibition properties of the combination of praseodymium nitrate (PrN) and Urtica Dioica (UrDi) on mild steel in sodium chloride solution. Fourier transform infrared (FT-IR), ultraviolet-visible (UV-Vis), thermogravimetric analysis/differential thermogravimetry (TGA/DTG) and X-ray photoelectron spectroscopy (XPS) results confirmed complex formation between Pr cations and UrDi (Pr-UrDi). Electrochemical results revealed that the Pr-UrDi hybrid complex had significant influence on the mild steel corrosion protection (by inhibition efficiency of ca. 94%) in NaCl solution.
S.M. Orouji,R. Naderi,M. Mahdavian 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.64 No.-
This work aims to study the effect of H2O2 in acid treatment solution on the protective properties of silane coating on mild steel. To this end, different concentrations of H2O2 up to 250 ppm were added to the sulfuric acid solution. The surface morphology, surface roughness, wettability and corrosion behavior of mild steel in the acid treatment solution were studied by SEM, GIXRD, AFM, contact angle, OCP and EIS. Then, a silane coating was applied onto the acid treated samples. It was found that H2O2 at optimal concentration (150 ppm) can improve corrosion protective properties of the silane coating.
Shima Alinejad,Reza Naderi,Mohammad Mahdavian 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.48 No.-
This work aims to study the impact of zinc cation and 2-mercaptobenzoxzole (MBO) on the corrosionprotection of a silane sol-gel coating on mild steel. First, effectiveness of the organic and inorganicinhibitors on the corrosion of bare mild steel in a NaCl solution was shown to be linked to formation of asurfacefilm. Using electrochemical data as well as results of surface analysis, a sharp inhibitionsynergism was found when an equal mole percentage of ZnCl2 and MBO was added to the NaCl solution. Finally, electrochemical data indicated superior performance of the coating with the combination ofinhibitors.