The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Digby D Macdonald - One of the best experts on this subject based on the ideXlab platform.
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effect of dissolved oxygen temperature and ph on polarization behavior of carbon steel in simulated concrete pore solution
Electrochimica Acta, 2021Co-Authors: Digby D Macdonald, Xiahe Liu, Mei WangAbstract:Abstract The Corrosion behaviour of carbon steel in simulated aerated concrete pore solution at different pH and temperature was investigated by in-situ Corrosion Potential, potentiodynamic polarization, and Tafel analysis, resulting in the deconvolution of the partial reactions. Fe dissolution is found to be independent of pH and dissoluble oxygen concentration (DO). Experimentally determined changes in the Corrosion Potential and the Corrosion resistance of the steel result from a combination of changes in the partial anodic reaction of steel electrodissolution and the cathodic reduction of water in deoxygenated solutions or from oxygen reduction in aerated solutions with temperature and DO are described.
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Corrosion of rebar in concrete part i calculation of the Corrosion Potential in the passive state
Corrosion Science, 2020Co-Authors: Digby D Macdonald, Jie Qiu, Yakun Zhu, Jie Yang, George R Engelhardt, Alberto A SaguesAbstract:Abstract Knowledge of the Corrosion Potential (ECP) in the passive condition is important in assessing Corrosion in reinforced concrete structures. While ECP is routinely measured, great scatter is reported, because the ECP is a sensitive function of many variables (T, [O2], pH, [Cl−], and the poorly defined mass transfer conditions). In this paper, a Mixed Potential Model (MPM) is used to calculate the ECP. The ECP shifts sharply in the negative direction when the passive current exceeds the limiting current density for oxygen transport to the steel surface. This shift is frequently misinterpreted as indicating passivity breakdown of the steel only.
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the efficiency of noble metals in reducing the Corrosion Potential in the primary coolant circuits of boiling water reactors operating under hydrogen water chemistry operation
Journal of Nuclear Science and Technology, 2006Co-Authors: Tsungkuang Yeh, Digby D MacdonaldAbstract:In order to promote the effectiveness of hydrogen water chemistry (HWC) and to achieve a more effective reduction in electrochemical Corrosion Potential (ECP) in the primary coolant circuits of boiling water reactors (BWRs), the technology of noble metal chemical addition (NMCA) was brought into practice about 10 years ago. NMCA aims at enhancing the oxidation of hydrogen on metal surfaces and lowering the concentrations of the oxidants (oxygen and hydrogen peroxide) via recombination with hydrogen on the catalyzed surfaces, and therefore reducing the Corrosion Potentials of the structural alloys in a BWR primary heat transport circuit. Previous research indicates that the effectiveness of NMCA in combination with a low HWC might be evaluated via model predictions of the hydrogen-to-oxidant molar ratio (MH/O) in the primary coolant circuit. If the MH/O at a certain location is calculated to be greater than 2, it is justified that the NMCA would be effective in reducing the ECP to much below the critical p...
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modeling water chemistry electrochemical Corrosion Potential and crack growth rate in the boiling water reactor heat transport circuits ii simulation of operating reactors
Nuclear Science and Engineering, 1996Co-Authors: Tsungkuang Yeh, Digby D MacdonaldAbstract:The DAMAGE-PREDICTOR computer code, which has the capability of simultaneously estimating the concentrations of radiolysis species, the electrochemical Corrosion Potential (ECP), and the crack growth rate (CGR) of a reference crack in sensitized Type 304 stainless steel, is used to evaluate the responses of the Dresden-2 and Duane Arnold boiling water reactors (BWRs) to hydrogen water chemistry (HWC). The HWC simulations for these two BWRs are carried out for feedwater hydrogen concentrations ([H 2 ]FW) ranging from 0.0 to 2.0 parts per million (ppm). Results such as species concentrations (H 2 , O 2 , H 2 O 2 , etc.), ECP, and CGR are predicted for various components in the heat transport circuits (HTCs) of the two reactors. It is found that while 1.3 ppm of feedwater hydrogen is needed to protect part of the lower downcomer, the recirculation system, and the lower plenum in Dresden-2 from intergranular stress Corrosion cracking, only 0.3 ppm is needed to achieve the same goal in Duane Arnold. However, it is also found that the ECP in many regions (core channel, core bypass, upper plenum, downcomer, etc.) in the HTCs cannot be lowered to below the critical Corrosion Potential of -0.23 V SHE for sensitized Type 304 stainless steels, even when [H 2 ] FW is as high as 2.0 ppm.
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modeling water chemistry electrochemical Corrosion Potential and crack growth rate in the boiling water reactor heat transport circuits i the damage predictor algorithm
Nuclear Science and Engineering, 1995Co-Authors: Digby D Macdonald, Arthur T MottaAbstract:A computer code with the capability of simultaneously estimating the concentrations of radiolysis species, the electrochemical Corrosion Potential, and the kinetics of growth of a reference crack in sensitized Type 304 stainless steel is developed for the heat transport circuits of boiling water reactors (BWRs). The primary objective of this code, DAMAGE-PREDICTOR, is to theoretically evaluate the effectiveness of hydrogen water chemistry (HWC) in the BWRs as a function of feedwater hydrogen concentration and reactor power level. The power level determines various important thermal-hydraulic parameters and the neutron and gamma energy deposition rate in the core and near-core regions. These input parameters are estimated using well-established algorithms, and the simulations are carried out for full-power conditions for two reactors that differ markedly in their responses to HWC. The DAMAGE-PREDICTOR code is found to successfully account for plant data from both reactors using a single set of model parameter values.
R. Romagnoli - One of the best experts on this subject based on the ideXlab platform.
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Lanthanum Derivative from “Tara” Tannin for Steel Temporary Protection
Industrial & Engineering Chemistry Research, 2018Co-Authors: Oriana D'alessandro, Cecilia Deyá, Alejandro R. Di Sarli, Gonzalo Julián Selmi, R. RomagnoliAbstract:Tannins are extracted from certain plants and contain numerous phenol groups. They may be employed, together with their derivatives, to formulate protective coatings due to their inhibitive properties. The objective of this research was to synthesize lanthanum “tannates”, to formulate wash-primers. Two “Tara” (Caesalpinia spinosa) tannins and 0.1 M La(NO3)3 were employed to obtain the corresponding tannates. The inhibitive action of the tannates was evaluated by linear polarization and Corrosion Potential measurements employing a SAE 1010 electrode. Lanthanum tannates were used to formulate wash-primers whose antiCorrosion performance was evaluated by Corrosion Potential and ionic resistance measurements. The primers were incorporated in alkyd paint systems and their antiCorrosion performance was tested in the salt spray chamber and by electrochemical impedance spectroscopy. Lanthanum tannate primers protected steel and behaved in a similar way to that formulated with zinc tetroxychromate.
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Lanthanum Derivative from “Tara” Tannin for Steel Temporary Protection
2018Co-Authors: Oriana D’alessandro, Alejandro R. Di Sarli, Gonzalo Julián Selmi, Cecilia Deyá, R. RomagnoliAbstract:Tannins are extracted from certain plants and contain numerous phenol groups. They may be employed, together with their derivatives, to formulate protective coatings due to their inhibitive properties. The objective of this research was to synthesize lanthanum “tannates”, to formulate wash-primers. Two “Tara” (Caesalpinia spinosa) tannins and 0.1 M La(NO3)3 were employed to obtain the corresponding tannates. The inhibitive action of the tannates was evaluated by linear polarization and Corrosion Potential measurements employing a SAE 1010 electrode. Lanthanum tannates were used to formulate wash-primers whose antiCorrosion performance was evaluated by Corrosion Potential and ionic resistance measurements. The primers were incorporated in alkyd paint systems and their antiCorrosion performance was tested in the salt spray chamber and by electrochemical impedance spectroscopy. Lanthanum tannate primers protected steel and behaved in a similar way to that formulated with zinc tetroxychromate
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Formulation and Assessment of a Wash-Primer Containing Lanthanum “Tannate” for Steel Temporary Protection
Journal of Materials Engineering and Performance, 2017Co-Authors: Oriana D'alessandro, Cecilia Deyá, Alejandro R. Di Sarli, Gonzalo Julián Selmi, R. RomagnoliAbstract:Tannins are polyphenols synthesized by plants and useful for the coating industry as Corrosion inhibitors. In addition, lanthanum salts have a great inhibitory effect on steel Corrosion. The aim of this study was to obtain lanthanum “tannate” with adequate solubility to be incorporated as the Corrosion inhibitor in a wash-primer. The “tannate” was obtained from commercial “Quebracho” tannin and 0.1 M La(NO3)3. The soluble tannin was determined by the Folin–Denis reagent, while the concentration of Lanthanum was obtained by a gravimetric procedure. The protective action of “tannate” on SAE 1010 steel was evaluated by linear polarization curves and Corrosion Potential measurements. Lanthanum “tannate” was incorporated in a wash-primer formulation and tested by Corrosion Potential and ionic resistance measurements. The Corrosion rate was also determined by the polarization resistance technique. Besides, the primer was incorporated in an alkyd paint system and its antiCorrosion performance assessed in the salt spray cabinet and by electrochemical impedance spectroscopy. Results showed that lanthanum “tannate” primer inhibits the development of deleterious iron oxyhydroxides on the steel substrate and incorporated into a paint system had a similar behavior to the primer formulated with zinc tetroxychromate.
Andrej Atrens - One of the best experts on this subject based on the ideXlab platform.
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influence of ph and chloride ion concentration on the Corrosion of mg alloy ze41
Corrosion Science, 2008Co-Authors: Andrej Atrens, Mingchun Zhao, Ming Liu, Guangling SongAbstract:The influence of pH and chloride ion concentration on the Corrosion behaviour of ZE41 was studied using immersion tests and electrochemical measurements. A shorter incubation period to the onset of Corrosion; a more negative Corrosion Potential; and a higher Corrosion rate correlated with a higher chloride ion concentration at each pH value and correlated with a lower pH Value for each chloride ion concentration. This Corrosion behaviour is consistent with the current understanding that the Corrosion behaviour of magnesium alloys is governed by a partially protective surface film, with the Corrosion reactions occurring predominantly at the breaks or imperfections of the partially protective film. The implication is that the fraction of film free surface increases with decreasing bulk pH and with increasing chloride ion concentration, This is consistent with the known tendency of chloride ions to cause film breakdown and the known instability of Mg(OH)(2) in solutions with pH less than 10.5. The electrochemical measurements of the Corrosion rate, based on the Corrosion current at the free Corrosion Potential, did not agree with direct measurements evaluated from the evolved hydrogen, in agreement with other observations for Mg, (C) 2008 Elsevier Ltd. All rights reserved.
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metallurgical aspects of rock bolt stress Corrosion cracking
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2008Co-Authors: Ernesto Villalba, Andrej AtrensAbstract:Abstract This paper reports on the metallurgical influence on rock bolt stress Corrosion cracking for a range of: (1) existing rock bolt steels and (2) commercial steels. Rock bolt steels 1355, MAC and MA840B displayed SCC when loaded at 0.019 MPa s −1 in the sulphate pH 2.1 solutions at the free Corrosion Potential. They had comparable threshold stresses and comparable stress Corrosion crack velocities. Rock bolts steel 5152CW10D had the best SCC resistance of the rock bolt steels tested. Cold work increased the resistance of 5152 to SCC. The five commercial steels 1008, X65, X70, 4140 and 4145H were subjected to the linearly increasing stress test (LIST) in the dilute pH 2.1 sulphate solution at their free Corrosion Potential and at increasingly negative applied Potential values to −1500 mV. The increasingly negative applied Potential increases the aggressivity of SCC conditions because of increasing hydrogen liberated at the specimen surface. The steels 1008, X65, X70 and 4145H resisted SCC for all applied Potentials including −1500 mV.
Tsungkuang Yeh - One of the best experts on this subject based on the ideXlab platform.
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the efficiency of noble metals in reducing the Corrosion Potential in the primary coolant circuits of boiling water reactors operating under hydrogen water chemistry operation
Journal of Nuclear Science and Technology, 2006Co-Authors: Tsungkuang Yeh, Digby D MacdonaldAbstract:In order to promote the effectiveness of hydrogen water chemistry (HWC) and to achieve a more effective reduction in electrochemical Corrosion Potential (ECP) in the primary coolant circuits of boiling water reactors (BWRs), the technology of noble metal chemical addition (NMCA) was brought into practice about 10 years ago. NMCA aims at enhancing the oxidation of hydrogen on metal surfaces and lowering the concentrations of the oxidants (oxygen and hydrogen peroxide) via recombination with hydrogen on the catalyzed surfaces, and therefore reducing the Corrosion Potentials of the structural alloys in a BWR primary heat transport circuit. Previous research indicates that the effectiveness of NMCA in combination with a low HWC might be evaluated via model predictions of the hydrogen-to-oxidant molar ratio (MH/O) in the primary coolant circuit. If the MH/O at a certain location is calculated to be greater than 2, it is justified that the NMCA would be effective in reducing the ECP to much below the critical p...
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modeling water chemistry electrochemical Corrosion Potential and crack growth rate in the boiling water reactor heat transport circuits ii simulation of operating reactors
Nuclear Science and Engineering, 1996Co-Authors: Tsungkuang Yeh, Digby D MacdonaldAbstract:The DAMAGE-PREDICTOR computer code, which has the capability of simultaneously estimating the concentrations of radiolysis species, the electrochemical Corrosion Potential (ECP), and the crack growth rate (CGR) of a reference crack in sensitized Type 304 stainless steel, is used to evaluate the responses of the Dresden-2 and Duane Arnold boiling water reactors (BWRs) to hydrogen water chemistry (HWC). The HWC simulations for these two BWRs are carried out for feedwater hydrogen concentrations ([H 2 ]FW) ranging from 0.0 to 2.0 parts per million (ppm). Results such as species concentrations (H 2 , O 2 , H 2 O 2 , etc.), ECP, and CGR are predicted for various components in the heat transport circuits (HTCs) of the two reactors. It is found that while 1.3 ppm of feedwater hydrogen is needed to protect part of the lower downcomer, the recirculation system, and the lower plenum in Dresden-2 from intergranular stress Corrosion cracking, only 0.3 ppm is needed to achieve the same goal in Duane Arnold. However, it is also found that the ECP in many regions (core channel, core bypass, upper plenum, downcomer, etc.) in the HTCs cannot be lowered to below the critical Corrosion Potential of -0.23 V SHE for sensitized Type 304 stainless steels, even when [H 2 ] FW is as high as 2.0 ppm.
Oriana D'alessandro - One of the best experts on this subject based on the ideXlab platform.
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Lanthanum Derivative from “Tara” Tannin for Steel Temporary Protection
Industrial & Engineering Chemistry Research, 2018Co-Authors: Oriana D'alessandro, Cecilia Deyá, Alejandro R. Di Sarli, Gonzalo Julián Selmi, R. RomagnoliAbstract:Tannins are extracted from certain plants and contain numerous phenol groups. They may be employed, together with their derivatives, to formulate protective coatings due to their inhibitive properties. The objective of this research was to synthesize lanthanum “tannates”, to formulate wash-primers. Two “Tara” (Caesalpinia spinosa) tannins and 0.1 M La(NO3)3 were employed to obtain the corresponding tannates. The inhibitive action of the tannates was evaluated by linear polarization and Corrosion Potential measurements employing a SAE 1010 electrode. Lanthanum tannates were used to formulate wash-primers whose antiCorrosion performance was evaluated by Corrosion Potential and ionic resistance measurements. The primers were incorporated in alkyd paint systems and their antiCorrosion performance was tested in the salt spray chamber and by electrochemical impedance spectroscopy. Lanthanum tannate primers protected steel and behaved in a similar way to that formulated with zinc tetroxychromate.
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Formulation and Assessment of a Wash-Primer Containing Lanthanum “Tannate” for Steel Temporary Protection
Journal of Materials Engineering and Performance, 2017Co-Authors: Oriana D'alessandro, Cecilia Deyá, Alejandro R. Di Sarli, Gonzalo Julián Selmi, R. RomagnoliAbstract:Tannins are polyphenols synthesized by plants and useful for the coating industry as Corrosion inhibitors. In addition, lanthanum salts have a great inhibitory effect on steel Corrosion. The aim of this study was to obtain lanthanum “tannate” with adequate solubility to be incorporated as the Corrosion inhibitor in a wash-primer. The “tannate” was obtained from commercial “Quebracho” tannin and 0.1 M La(NO3)3. The soluble tannin was determined by the Folin–Denis reagent, while the concentration of Lanthanum was obtained by a gravimetric procedure. The protective action of “tannate” on SAE 1010 steel was evaluated by linear polarization curves and Corrosion Potential measurements. Lanthanum “tannate” was incorporated in a wash-primer formulation and tested by Corrosion Potential and ionic resistance measurements. The Corrosion rate was also determined by the polarization resistance technique. Besides, the primer was incorporated in an alkyd paint system and its antiCorrosion performance assessed in the salt spray cabinet and by electrochemical impedance spectroscopy. Results showed that lanthanum “tannate” primer inhibits the development of deleterious iron oxyhydroxides on the steel substrate and incorporated into a paint system had a similar behavior to the primer formulated with zinc tetroxychromate.
