oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Electrochemical Impedance Spectroscopy of Hybrid Epoxy Resin Emulsion Coatings  [PDF]
Rakesh N. Patil, Brihbihari V. Sharma, Prakash A. Mahanwar
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2012, DOI: 10.4236/jmmce.2012.1110104
Abstract: A hybrid epoxy resin one pack emulsion with acrylate was synthesized for application in the field of corrosion protec- tion. Electrochemical impedance tests were applied to steel specimens coated with hybrid epoxy and tested after im- mersion in 3.5% NaCl solution at room temperature. Results taken from Nyquist and Bode plots as were analyzed by means of software provided with the instrument. Specimens were examined under scanning electron microscope shows a clear rupture and degradation in hybrid epoxy coating after prolonged exposer to salt solution.
Adhesion of epoxy cataphoretic coatings on Zn alloys
JELENA B. BAJAT,VESNA B. MISKOVIC–STANKOVIC,DRAGUTIN M. DRAZIC
Journal of the Serbian Chemical Society , 2007,
Abstract: One of the most important factors in corrosion prevention by protective coatings is the loss of coating adhesion under environmental influence. In this work, the adhesion of epoxy cataphoretic coatings was examined on steel and steel modified by Zn–Fe and Zn–Co alloys. The dry and wet adhesions of epoxy primers were measured by the direct pull-off standardized procedure, as well as indirectly by the NMP test. The corrosion stability of the coated samples was investigated by electrochemical impedance spectroscopy. It was shown that under dry testing conditions all the samples exhibited very good adhesion. However, different trends of adhesion loss of different protective systems during exposure to a corrosive agent (3 % NaCl solution) were observed. The lowest adhesion values were obtained for epoxy coating on the steel substrate. The change in adhesion of the epoxy coating on steel modified by Zn–Co alloy during immersion in 3 % NaCl solution for 24 days was the smallest of all the investigated samples. Electrochemical impedance measurements in 3 % NaCl solution confirmed the good protective properties of this protective system, i.e., greater values of pore resistance were obtained.
In-Situ Corrosion Monitoring of Scratched Epoxy Coated Carbon Steel in Saturated Ca(OH)2 with or without 3% NaCl by Scanning Electrochemical Microscopy and Electrochemical Impedance Spectroscopy  [PDF]
Thangaraj Balusamy, Toshiyasu Nishimura
American Journal of Analytical Chemistry (AJAC) , 2016, DOI: 10.4236/ajac.2016.77049
Abstract: The present work is investigated the in-situ monitoring of local corrosion process of scratched epoxy coated carbon steel in saturated Ca(OH)2 with and without 3% NaCl using SECM and correlated with EIS. The results obtained from EIS analysis showed that the corrosion resistance of scratched epoxy coated carbon steel decreases in Cl- containing solution as the increase in wet/ dry corrosion cycles. This was indicated by decrease in film resistance (Rf) and charge transfer resistance (Rct), while the coated steel maintain the resistance values in saturated Ca(OH)2, most of which recovered after drying. The corrosion process was monitored using SECM by setting the tip potential at -0.70 V vs Ag/AgCl, where the consumption of dissolved oxygen occurred at the surface of test sample. The consumption of dissolved oxygen current (Ioxy-c) values was increased during the immersion in a solution with 3% NaCl. However, in wet/dry corrosion cycles, Ioxy-c was decreased due to the coverage of hydroxides/oxides at scratch area which suppressed the consumption of dissolved O2. It was found that the continuous decrease in corrosion was mainly attributed to continuous formation of corrosion products at anodic spots.
Protective Performance of Water-Based Epoxy Coating Containing ScCO2 Synthesized Self-Doped Nanopolyaniline  [PDF]
M. R. Bagherzadeh,T. Mousavinejad,E. Akbarinezhad,A. Ghanbarzadeh
Physics , 2013,
Abstract: In this research, corrosion properties of water-based epoxy coating is improved by adding self-doped nano polyaniline (SPAni) synthesized using supercritical carbon dioxide (ScCO2) medium. The modified ScCO2-synthesized self-doped nano polyaniline (SPAni) using water-based polyamidoamine hardener results formation of the water-based SPAni composite (Sc-WB). To obtain the water-based polyaniline epoxy coating (SP-WBE), the Sc-WB was mixed with epoxy resin in stoichiometric ratio. The formation of oxide layers and adhesion properties of SP-WBE at corrosive medium was evaluated using scanning electron microscopy (SEM) studies. The transmission electron microscopy (TEM) was used to observe the distribution and particles size of nanopolyaniline in the final dried film. The anti-corrosion performance of water-based epoxy coated sample (blank coated sample) and SP-WBE coated sample was studied using salt spray standard test according to ASTM B-117, electrochemical impedance spectroscopy (EIS) and adhesion tests. The results indicate protective performance of water-based epoxy coating is improved by adding self-doped polyaniline synthesized at ScCO2 situation. The electrical resistance of the coatings containing nanopolyaniline and the blank sample was 1.8778E+7 {\Omega}.cm2 and 2.512E+5 {\Omega}.cm2 after 1800 hours of immersion in 3.5 Wt% NaCl aqua corrosive solutions.
EVALUATION OF PROTECTING PROPERTIES OF EPOXY COATINGS ON NAVY STEEL BY ELECTROCHEMICAL IMPEDANCE ESPECTROSCOPY
Ramírez,D.; Vera,R.; Gómez,H.; Co?ajahua,C.;
Journal of the Chilean Chemical Society , 2005, DOI: 10.4067/S0717-97072005000200010
Abstract: electrochemical impedance spectroscopy (eis), open circuit potential (o.c.p.) measurements and saline fog chamber experiments were employed to study the protective action of four epoxy coatings on navy steel immersed in artificial seawater. from eis data such as pore resistance, coating capacitance, and the use of the proper electric equivalent circuits it was possible to obtain information regarding the corrosion behavior under each coating. results have been interpreted under the assumption that it is possible to predict the lifetime of conventional paintings as compared with chemically modified coatings. after 40 days of immersion, variable results between electrochemical experiments and saline fog chamber experiments were obtained
EVALUATION OF PROTECTING PROPERTIES OF EPOXY COATINGS ON NAVY STEEL BY ELECTROCHEMICAL IMPEDANCE ESPECTROSCOPY  [cached]
D. Ramírez,R. Vera,H. Gómez,C. Co?ajahua
Journal of the Chilean Chemical Society , 2005,
Abstract: Electrochemical Impedance Spectroscopy (EIS), open circuit potential (o.c.p.) measurements and saline fog chamber experiments were employed to study the protective action of four epoxy coatings on navy steel immersed in artificial seawater. From EIS data such as pore resistance, coating capacitance, and the use of the proper electric equivalent circuits it was possible to obtain information regarding the corrosion behavior under each coating. Results have been interpreted under the assumption that it is possible to predict the lifetime of conventional paintings as compared with chemically modified coatings. After 40 days of immersion, variable results between electrochemical experiments and saline fog chamber experiments were obtained
Dye-Sensitized Solar Cells Using Surface-Stabilized Nanocrystalline-TiO2 Electrodes Coated by Epoxy Polymer  [cached]
Kazuki Tsujimoto,Seigo Ito,Shinichi Yusa,Takayuki Imamura
Energy Science and Technology , 2011, DOI: 10.3968/j.est.1923847920110202.125
Abstract: In order to improve the thermal durability of dye-sensitized solar cells, epoxy polymer was coated on dyed-TiO2 electrode to prevent dye desorption under heating condition over 80 °C. The covering effect on epoxy polymer was confirmed using impedance spectroscopy. Using the epoxy polymer coating with Z907 Ru dye and ionic liquid electrolyte, the DSC photovoltaic durability was improved up to 90 °C, which is the highest temperature published for the DSC durability test. Although the epoxy polymer suppressed the DSC photovoltaic effect, it enhance the thermal durability; DSC coated epoxy polymer on the dyed-TiO2 electrode was able to prolong the efficiency over 90% of the initial value at 90 °C for 550 hours. Key words: Dye-sensitized solar cells; Epoxy polymer; Ionic liquid electrolyte; Thermal durability; Heat test
Electrochemical Impedance Study of Zinc Yellow Polypropylene-Coated Aluminum Alloy  [PDF]
Zhi-hua Sun,Jian-ping Cai,Ming Liu,Feng Lu,Ni Zhang
International Journal of Corrosion , 2010, DOI: 10.1155/2010/528573
Abstract: Performance of zinc yellow polypropylene-coated aluminum alloy 7B04 during accelerated degradation test is studied using electrochemical impedance spectroscopy (EIS). It has been found that the zinc yellow polypropylene paint has few flaw and acts as a pure capacitance before accelerated test. After 336-hour exposure to the test, the impedance spectroscopy shows two time constants, and water has reached to the aluminum alloy/paint interface and forms corrosive microcell. For the scratched samples, the reaction of metal corrosion and the hydrolysis of zinc yellow ion can occur simultaneously. The impedance spectroscopy indicates inductance after 1008-hour exposure to the test, but the inductance disappears after 1344-hour exposure and the passivation film has pitting corrosion. 1. Introduction Organic coatings have been widely applied to control the corrosion of airplanes for many years [1, 2]. The performance of organic coatings, which generally relates to their barrier performance character against water, oxygen, and ions and to their good adhesion to substrate impeding delamination, seriously influences their protection efficiencies to metallic substrates [3, 4]. However, organic coatings can degrade under various service conditions and the degradation process of paints is complicated since it is affected by several factors, such as humidity, heat impact,ultraviolet (UV) radiation, salt fog, pollutants (like ), low temperature fatigue, and other exotic (like dust) [5, 6]. The degradation evaluation can be visual, mechanical, electrochemical, and so furth. The use of electrochemical techniques combined with accelerated tests has resulted in new information concerning the degradation mechanisms of organic coatings in corrosive environments [7, 8]. In particular, electrochemical impedance spectroscopy (EIS) has been shown to be very useful technique for the study of the performance of anticorrosive primers [9, 10]. Zinc yellow polypropylene primer has been widely used in aeronautical industry, and its EIS study has been carried out. But the research mainly focus on its impedance measurement with exposure time after immersion to certain solution, such as NaCl solution [11, 12], and the failure characteristics after exposure to accelerated test simulating the service conditions have not been investigated. In the present work, electrochemical impedance varieties of zinc yellow polypropylene-coated aluminum alloy 7B04 used in aircraft during accelerated test to simulate its service condition are studied using EIS, and the characteristics of corrosive failure
Electromagnetic Wave Scattering By the Coated Impedance Cylinder  [PDF]
V.I. Vyunnik,A.A, Zvyagintsev
Journal of Nano- and Electronic Physics , 2010,
Abstract: In this work the boundary conditions for the impedance circular cylinder coated by a low contrast dielectric thin layer are derived. Expression for the reduced impedance of the cylinder is obtained. Conditions and applicability limits of the proposed approach are defined. Influence of the coating impedance on the reduced impedance of the cylinder is investigated.
Electrochemical impedance spectroscopy of multi-layer epoxy coatings in NaCl solution
多道环氧涂层在NaCl溶液中的电化学阻抗谱

XIE Deming HU Jiming TONG Shaoping,
谢德明
,胡吉明,童少平

材料研究学报 , 2004,
Abstract: The diffusion behavior of water through epoxy coatings as a function of the film thickness and the painting number was studied by electrochemical impedance spectroscopy (EIS) techniques. The experimental results showed that, in 3.5 wt.% NaCl solution, the diffusion process of water through multi-layer organic coatings with good barrier performance followed the ideal Fick's law in the initial period. The corresponding diffusion coefficient was also derived and the dielectric constant of the dry coatings (ed) was found to be 4.2. The resistance to medium permeation of the coatings increased with increasing of film thickness and the number of coats.
Page 1 /100
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.