The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Haibing Zheng - One of the best experts on this subject based on the ideXlab platform.
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influence of calcium ion in concrete pore solution on the passivation of Galvanized Steel bars
Cement and Concrete Research, 2018Co-Authors: Haibing Zheng, Weihua Li, Chi Sun PoonAbstract:Abstract The addition of supplementary cementitious materials may affect the Ca 2+ concentration and pH value of the concrete pore solutions. This work studied the influence of the calcium ion on the passivation of the Galvanized Steel bars in simulated concrete pore solutions with relatively low pH value of 12.5 and 13.15. The results showed that continuous protective layers were formed on the Galvanized coating in the solutions with saturated Ca(OH) 2 at pH 12.5 and solutions with either KOH or NaOH at pH 13.15. The passive film formed in the saturated Ca(OH) 2 solution showed better protective properties than those in other solutions. In the solutions with lower concentrations of Ca 2+ at pH 12.5, there was no obvious reaction and no protective layer was formed on the surface.
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influence of chloride ion on depassivation of passive film on Galvanized Steel bars in concrete pore solution
Construction and Building Materials, 2018Co-Authors: Haibing Zheng, Weihua Li, Chi Sun PoonAbstract:Abstract This work aimed at studying the depassivation mechanism of the passive film on Galvanized Steel bar in concrete pore solution with different concentrations of chloride ion. The results showed that in a saturated Ca(OH)2 solution, the critical chloride values for the depassivation of the passive films formed on Galvanized Steel bars and zinc metal specimens were 0.2 M and 0.3 M respectively. When the Cl− concentration was lower than the critical value, the donor density of the passive film increased and thus the protective property reduced with increasing the concentration of chloride ion, which could be interpreted by the point defect model (PDM). The corrosion products formed on the Galvanized Steel surface could inhibit the further ingress of the chloride ions and enhance the protective property, while such effect was not obvious for the zinc metal.
Weihua Li - One of the best experts on this subject based on the ideXlab platform.
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influence of calcium ion in concrete pore solution on the passivation of Galvanized Steel bars
Cement and Concrete Research, 2018Co-Authors: Haibing Zheng, Weihua Li, Chi Sun PoonAbstract:Abstract The addition of supplementary cementitious materials may affect the Ca 2+ concentration and pH value of the concrete pore solutions. This work studied the influence of the calcium ion on the passivation of the Galvanized Steel bars in simulated concrete pore solutions with relatively low pH value of 12.5 and 13.15. The results showed that continuous protective layers were formed on the Galvanized coating in the solutions with saturated Ca(OH) 2 at pH 12.5 and solutions with either KOH or NaOH at pH 13.15. The passive film formed in the saturated Ca(OH) 2 solution showed better protective properties than those in other solutions. In the solutions with lower concentrations of Ca 2+ at pH 12.5, there was no obvious reaction and no protective layer was formed on the surface.
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influence of chloride ion on depassivation of passive film on Galvanized Steel bars in concrete pore solution
Construction and Building Materials, 2018Co-Authors: Haibing Zheng, Weihua Li, Chi Sun PoonAbstract:Abstract This work aimed at studying the depassivation mechanism of the passive film on Galvanized Steel bar in concrete pore solution with different concentrations of chloride ion. The results showed that in a saturated Ca(OH)2 solution, the critical chloride values for the depassivation of the passive films formed on Galvanized Steel bars and zinc metal specimens were 0.2 M and 0.3 M respectively. When the Cl− concentration was lower than the critical value, the donor density of the passive film increased and thus the protective property reduced with increasing the concentration of chloride ion, which could be interpreted by the point defect model (PDM). The corrosion products formed on the Galvanized Steel surface could inhibit the further ingress of the chloride ions and enhance the protective property, while such effect was not obvious for the zinc metal.
Chi Sun Poon - One of the best experts on this subject based on the ideXlab platform.
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influence of calcium ion in concrete pore solution on the passivation of Galvanized Steel bars
Cement and Concrete Research, 2018Co-Authors: Haibing Zheng, Weihua Li, Chi Sun PoonAbstract:Abstract The addition of supplementary cementitious materials may affect the Ca 2+ concentration and pH value of the concrete pore solutions. This work studied the influence of the calcium ion on the passivation of the Galvanized Steel bars in simulated concrete pore solutions with relatively low pH value of 12.5 and 13.15. The results showed that continuous protective layers were formed on the Galvanized coating in the solutions with saturated Ca(OH) 2 at pH 12.5 and solutions with either KOH or NaOH at pH 13.15. The passive film formed in the saturated Ca(OH) 2 solution showed better protective properties than those in other solutions. In the solutions with lower concentrations of Ca 2+ at pH 12.5, there was no obvious reaction and no protective layer was formed on the surface.
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influence of chloride ion on depassivation of passive film on Galvanized Steel bars in concrete pore solution
Construction and Building Materials, 2018Co-Authors: Haibing Zheng, Weihua Li, Chi Sun PoonAbstract:Abstract This work aimed at studying the depassivation mechanism of the passive film on Galvanized Steel bar in concrete pore solution with different concentrations of chloride ion. The results showed that in a saturated Ca(OH)2 solution, the critical chloride values for the depassivation of the passive films formed on Galvanized Steel bars and zinc metal specimens were 0.2 M and 0.3 M respectively. When the Cl− concentration was lower than the critical value, the donor density of the passive film increased and thus the protective property reduced with increasing the concentration of chloride ion, which could be interpreted by the point defect model (PDM). The corrosion products formed on the Galvanized Steel surface could inhibit the further ingress of the chloride ions and enhance the protective property, while such effect was not obvious for the zinc metal.
M. G. S. Ferreira - One of the best experts on this subject based on the ideXlab platform.
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initial stages of localized corrosion at cut edges of adhesively bonded zn and zn al mg Galvanized Steel
Electrochimica Acta, 2016Co-Authors: K A Yasakau, M. G. S. Ferreira, Silvar Kallip, Aleksey D Lisenkov, Mikhail L. ZheludkevichAbstract:Abstract The mechanisms of the initial stages of localized corrosion at cut edges were investigated for adhesively bonded Zn (Z) and Zn-Al-Mg (ZM) Galvanized Steel. The results provided strong evidence for the localized nature of corrosion of Galvanized coatings at the cut edges and at the adhesive/zinc interface. In both cases a defined localized corrosion attack on zinc in Z sample was observed. On the contrary, in the case of the ZM specimen both zinc solid solution and eutectics exhibited local corrosion. The local attack at the adhesive/Z(ZM) interface was correlated with an anodic undermining process. It develops near the cut-edge surface and at the buried deep adhesive-zinc interface and results in adhesive disbonding in the buried interface. The electrochemical studies revealed that the corrosion kinetics at the metal cut-edges decreases during immersion, which could be due to formation of corrosion products on both Steel and zinc surfaces.
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the corrosion resistance of hot dip Galvanized Steel pretreated with bis functional silanes modified with microsilica
Surface & Coatings Technology, 2006Co-Authors: M. Fátima Montemor, Mikhail L. Zheludkevich, A.m. Cabral, M. G. S. FerreiraAbstract:Abstract The present work aims at understanding the corrosion behaviour of hot dip Galvanized Steel pretreated with either bis-1,2-[triethoxysilyl]ethane silane (BTSE) or bis-[triethoxysilylpropyl] tetrasulfide (BTESPT) modified with microparticles of SiO 2 . The corrosion resistance was evaluated by electrochemical impedance spectroscopy, potentiodynamic polarization and by the scanning vibrational electrode technique (SVET) during immersion in dilute NaCl solutions. The films formed on the Galvanized Steel substrate were characterized by X-ray photoelectron spectroscopy, Auger electron spectroscopy and atomic force microscopy. The results show that the pretreatments based on silane films modified with silica particles provide corrosion protection for hot dip Galvanized Steel during immersion in NaCl-containing solutions.
D M Dražic - One of the best experts on this subject based on the ideXlab platform.
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the influence of zinc surface pretreatment on the adhesion of epoxy coating electrodeposited on hot dip Galvanized Steel
Progress in Organic Coatings, 2007Co-Authors: Jelena B. Bajat, V Miskovicstankovic, N Bibic, D M DražicAbstract:The adhesion and electrochemical properties of epoxy coatings electrodeposited on hot-dip Galvanized Steel with and without passive films were investigated during exposure to 3% NaCl. The passive films were formed in hot air, in boiling water and by chromating. Adhesion was measured both by a standardized pull-off method and by swelling in N-methyl pyrrolidone. Pretreatment of hot-dip Galvanized Steel with passive film formed in hot air increases both dry and wet adhesion strength of the epoxy coating compared to pretreatment with passive film formed in boiling water and chromate coating. The overall increase of wet adhesion for this sample was maintained throughout the whole investigated time period. It was shown that the change in adhesion of epoxy coating on a chromate coating is smallest of all investigated samples, although the initial value of adhesion on this surface had the lowest value. The corrosion stability of coated Zn samples pretreated by different methods, was investigated by electrochemical impedance spectroscopy and in the initial time of exposure to NaCl the highest values of pore resistance were also obtained for the epoxy coating on Zn pretreated in hot air, whereas the epoxy coating on a HDG Steel with a chromate coating showed the smallest change in electrochemical properties (pore resistance, coating capacitance, charge-transfer resistance) during prolonged exposure time.
