Based on three different kinds of conductive paths in microstructure of soil and theory of electrochemical impedance spectroscopy(EIS), an integrated equivalent circuit model and impedance formula for soils were propo...Based on three different kinds of conductive paths in microstructure of soil and theory of electrochemical impedance spectroscopy(EIS), an integrated equivalent circuit model and impedance formula for soils were proposed, which contain 6 meaningful resistance and reactance parameters. Considering the conductive properties of soils and dispersion effects, mathematical equations for impedance under various circuit models were deduced and studied. The mathematical expression presents two semicircles for theoretical EIS Nyquist spectrum, in which the center of one semicircle is degraded to simply the equivalent model. Based on the measured parameters of EIS Nyquist spectrum, meaningful soil parameters can easily be determined. Additionally, EIS was used to investigate the soil properties with different water contents along with the mathematical relationships and mechanism between the physical parameters and water content. Magnitude of the impedance decreases with the increase of testing frequency and water content for Bode graphs. The proposed model would help us to better understand the soil microstructure and properties and offer more reasonable explanations for EIS spectra.展开更多
The corrosion inhibition for carbon steel in circulating cooling water by modified lignosulphonate has been investigated using electrochemical impedance spectroscopy technique. Results show that the inhibition efficie...The corrosion inhibition for carbon steel in circulating cooling water by modified lignosulphonate has been investigated using electrochemical impedance spectroscopy technique. Results show that the inhibition efficiency of modified lignosulphonate GCL2 is a great improvement on that of lignosulphonate. The maximum inhibition efficiency of GCL2 reaches 99.21% at the concentration of 400mg·L^-1 at 303K. The corrosion inhibition of GCL2 is attributed to forming adsorption film on the metal surface for the electrochemical impedance spectroscopy in GCL2 solution shows more than one time-constant.Moreover,results also indicate that it is more efficient in stirring solution than in still solution for GCL2 because the constant of adsorption in stirring solution is much larger than that in still solution. The adsorption of inhibitor GCL2 follows Langmuir＇s adsorption isotherm.展开更多
The electrochemical characteristics of 1Cr18Ni9Ti in sulphate-reducing bacteria （SRB） solutions and the biofilm of SRB on the surface of the 1Cr18Ni9Ti electrode were studied by electrochemical, microbiological, and...The electrochemical characteristics of 1Cr18Ni9Ti in sulphate-reducing bacteria （SRB） solutions and the biofilm of SRB on the surface of the 1Cr18Ni9Ti electrode were studied by electrochemical, microbiological, and surface analysis methods. Electrochemical impedance spectroscopy （EIS） of 1Cr18Ni9Ti was measured in the solutions with and without SRB at the culture time of 2, 4, 8 d, respectively. The measurement used two test methods, the nonimmersion electrode method and the immersion electrode method. It was found that the polarization resistance （Rp） of 1Cr18Ni9Ti in the solutions without SRB is the greatest for each test method. When using the nonimmersion electrode method, Rp shifts negatively at first and then positively, and the time constant is only one. Although using the immersion electrode method, the Rp shifts positively at first and then negatively, and the time constant also changes when the biofilm forms. The biofilm observed through SEM is with pores. It was demonstrated that SRB has accelerated corrosion action on 1Cr18Ni9Ti. The protection effect of the biofilm on the electrode depends on the compact degree of the film.展开更多
The exfoliation corrosion susceptibility and electrochemical impedance spectrosc opy(EIS) of rolled and peak-aged 8090 Al-Li alloys in EXCO solution were studi ed,and the EIS after exfoliation was simulated. Once exfo...The exfoliation corrosion susceptibility and electrochemical impedance spectrosc opy(EIS) of rolled and peak-aged 8090 Al-Li alloys in EXCO solution were studi ed,and the EIS after exfoliation was simulated. Once exfoliation occurs,two ca pacitive arcs appear in the EIS at high-mediate frequency and mediate-low freq uency respectively. The exfoliation-attacked alloy surface consists of two part s,an original flat alloy surface and a new inter-face exposed to EXCO solution due to the exfoliation. The capacitance corresponding to the new exfoliation in ter-face increases approximately linearly with time at early exfoliation stage,due to the enlargement of the new inter-face. Then it maintains stable,due to the corrosion product covering on the new inter-face. The exfoliation suscepti bility can be judged through the average slope of the capacitance vs time curve of the early exfoliation stage. This average slope of the rolled 8090 alloy is m uch higher than that of the peak-aged 8090 alloy,accordingly the rolled 8090 a lloy is more susceptible to exfoliation than the peak-aged 8090 alloy.展开更多
The exfoliation morphologies and electrochemical impedance spectroscopy (EIS) features of as received rolled AA8090 Al Li alloy in EXCO solution were studied. The EIS was simulated using an equivalent circuit. The res...The exfoliation morphologies and electrochemical impedance spectroscopy (EIS) features of as received rolled AA8090 Al Li alloy in EXCO solution were studied. The EIS was simulated using an equivalent circuit. The results show that once the exfoliation occurs, the EIS is composed of two capacitive arcs at high frequency and mediate low frequency; among them, the capacitance corresponding to high frequency ( C 1) is originated from original flat alloy surface, while the capacitance corresponding to mediate low frequency ( C 2) from new interface exposed to EXCO solution due to the exfoliation and the ratio of C 2 to C 1 increases with exfoliation degree. It is advanced that the exfoliation degree can be quantitatively judged through this ratio.展开更多
Degradation behavior is the main technical problem in the field of commercial application of lithiumion batteries. According to the characteristics of voltage, discharge capacity and inner resistance during the charge...Degradation behavior is the main technical problem in the field of commercial application of lithiumion batteries. According to the characteristics of voltage, discharge capacity and inner resistance during the charge/discharge process of commercial lithium-ion batteries of mobile telephone, degradation analysis and related mechanisms are put forward and discussed in the paper. The impedance spectra of prismatic commercial lithium-ion batteries are measured at various state of charge after different charge/discharge cycles. The incastared impedance spectra are discussed with a proposed equivalent circuit. Results indicated that the structure change of electrode materials or swell and shrink of crystal lattice, decompose of electrolyte, dissolution of active materials and solid electrolyte interphase film formation are the main reasons leading to the capacity degradation.展开更多
The corrosion behaviors and corresponding electrochemical impedance spectroscopy（EIS） and polarization curves of pure Mg in neutral 1.0% NaCl solution were investigated.The fractal dimension of EIS at different time...The corrosion behaviors and corresponding electrochemical impedance spectroscopy（EIS） and polarization curves of pure Mg in neutral 1.0% NaCl solution were investigated.The fractal dimension of EIS at different time was studied.The corrosion process and EIS evolution are divided into three stages.In the initial stage,EIS is composed of two overlapped capacitive arcs,the polarization resistance and charge transfer resistance increase rapidly with immersion time,and the corrosion rate decreases.Then,two well-defined capacitive arcs appear,and the charge transfer resistance and corrosion rate remain stable.After a long immersion time,inductive component appears in a low frequency range,the charge transfer resistance decreases and the corrosion rate increases with the immersion time.The fractal dimension obtained from the time records of EIS seems to be a promising tool for the analysis of corrosion morphology because of its direct relationship with the metal surface.展开更多
Electrochemical impendence spectroscopy （EIS） is applied to investigate the dissolution behavior of Al-Zn alloys in 3% NaCl solution at different polarization potentials. A new reaction model is proposed, and the ac...Electrochemical impendence spectroscopy （EIS） is applied to investigate the dissolution behavior of Al-Zn alloys in 3% NaCl solution at different polarization potentials. A new reaction model is proposed, and the activation mechanism of zinc in Al-Zn alloys is achieved. There are three intermediates in the dissolution process： Znad^＋, Znad^2＋ and Alad^＋, ,of which only Zni can activate Al-Zn alloys. Most Znnd^＋ is produced by β-phase,and the alloys with 2. 3% - 3. 8% （wt） Zn dissolve rapidly. The Al-Zn alloys of heart-shaped EIS are active in 3% NaCl solution, thus EIS characteristic can be used to distinguish the activa-tion of Al-Zn alloys.展开更多
基金Projects(5120833351078253)supported by the National Natural Science Foundation of China+4 种基金Projects(2014011036-12014131019TYUT2014YQ017OIT2015)supported by the Natural Science Foundation of Shanxi ProvinceChina
文摘Based on three different kinds of conductive paths in microstructure of soil and theory of electrochemical impedance spectroscopy(EIS), an integrated equivalent circuit model and impedance formula for soils were proposed, which contain 6 meaningful resistance and reactance parameters. Considering the conductive properties of soils and dispersion effects, mathematical equations for impedance under various circuit models were deduced and studied. The mathematical expression presents two semicircles for theoretical EIS Nyquist spectrum, in which the center of one semicircle is degraded to simply the equivalent model. Based on the measured parameters of EIS Nyquist spectrum, meaningful soil parameters can easily be determined. Additionally, EIS was used to investigate the soil properties with different water contents along with the mathematical relationships and mechanism between the physical parameters and water content. Magnitude of the impedance decreases with the increase of testing frequency and water content for Bode graphs. The proposed model would help us to better understand the soil microstructure and properties and offer more reasonable explanations for EIS spectra.
基金supported by the National Natural Science Foundation of China(No.20276024)the Guangdong Provincial Laboratory of Green Chemical Technology
文摘The corrosion inhibition for carbon steel in circulating cooling water by modified lignosulphonate has been investigated using electrochemical impedance spectroscopy technique. Results show that the inhibition efficiency of modified lignosulphonate GCL2 is a great improvement on that of lignosulphonate. The maximum inhibition efficiency of GCL2 reaches 99.21% at the concentration of 400mg·L^-1 at 303K. The corrosion inhibition of GCL2 is attributed to forming adsorption film on the metal surface for the electrochemical impedance spectroscopy in GCL2 solution shows more than one time-constant.Moreover,results also indicate that it is more efficient in stirring solution than in still solution for GCL2 because the constant of adsorption in stirring solution is much larger than that in still solution. The adsorption of inhibitor GCL2 follows Langmuir＇s adsorption isotherm.
文摘The electrochemical characteristics of 1Cr18Ni9Ti in sulphate-reducing bacteria （SRB） solutions and the biofilm of SRB on the surface of the 1Cr18Ni9Ti electrode were studied by electrochemical, microbiological, and surface analysis methods. Electrochemical impedance spectroscopy （EIS） of 1Cr18Ni9Ti was measured in the solutions with and without SRB at the culture time of 2, 4, 8 d, respectively. The measurement used two test methods, the nonimmersion electrode method and the immersion electrode method. It was found that the polarization resistance （Rp） of 1Cr18Ni9Ti in the solutions without SRB is the greatest for each test method. When using the nonimmersion electrode method, Rp shifts negatively at first and then positively, and the time constant is only one. Although using the immersion electrode method, the Rp shifts positively at first and then negatively, and the time constant also changes when the biofilm forms. The biofilm observed through SEM is with pores. It was demonstrated that SRB has accelerated corrosion action on 1Cr18Ni9Ti. The protection effect of the biofilm on the electrode depends on the compact degree of the film.
文摘The exfoliation corrosion susceptibility and electrochemical impedance spectrosc opy(EIS) of rolled and peak-aged 8090 Al-Li alloys in EXCO solution were studi ed,and the EIS after exfoliation was simulated. Once exfoliation occurs,two ca pacitive arcs appear in the EIS at high-mediate frequency and mediate-low freq uency respectively. The exfoliation-attacked alloy surface consists of two part s,an original flat alloy surface and a new inter-face exposed to EXCO solution due to the exfoliation. The capacitance corresponding to the new exfoliation in ter-face increases approximately linearly with time at early exfoliation stage,due to the enlargement of the new inter-face. Then it maintains stable,due to the corrosion product covering on the new inter-face. The exfoliation suscepti bility can be judged through the average slope of the capacitance vs time curve of the early exfoliation stage. This average slope of the rolled 8090 alloy is m uch higher than that of the peak-aged 8090 alloy,accordingly the rolled 8090 a lloy is more susceptible to exfoliation than the peak-aged 8090 alloy.
文摘The exfoliation morphologies and electrochemical impedance spectroscopy (EIS) features of as received rolled AA8090 Al Li alloy in EXCO solution were studied. The EIS was simulated using an equivalent circuit. The results show that once the exfoliation occurs, the EIS is composed of two capacitive arcs at high frequency and mediate low frequency; among them, the capacitance corresponding to high frequency ( C 1) is originated from original flat alloy surface, while the capacitance corresponding to mediate low frequency ( C 2) from new interface exposed to EXCO solution due to the exfoliation and the ratio of C 2 to C 1 increases with exfoliation degree. It is advanced that the exfoliation degree can be quantitatively judged through this ratio.
基金"973"Project (2002CB211800)Teaching and Research Fund of Beijing Institute of Technology(20070542008)
文摘Degradation behavior is the main technical problem in the field of commercial application of lithiumion batteries. According to the characteristics of voltage, discharge capacity and inner resistance during the charge/discharge process of commercial lithium-ion batteries of mobile telephone, degradation analysis and related mechanisms are put forward and discussed in the paper. The impedance spectra of prismatic commercial lithium-ion batteries are measured at various state of charge after different charge/discharge cycles. The incastared impedance spectra are discussed with a proposed equivalent circuit. Results indicated that the structure change of electrode materials or swell and shrink of crystal lattice, decompose of electrolyte, dissolution of active materials and solid electrolyte interphase film formation are the main reasons leading to the capacity degradation.
基金Foundation item: Projects (50771092, 21073162) supported by the National Natural Science Foundation of ChinaProject (2008) supported by the Scientific and Technological projects of Ningxia Province, China+1 种基金Project (08JC1421600) supported by the Science and Technology Commission of Shanghai,ChinaProject (2008AZ2018) supported by the Science and Technology Bureau of Jiaxing,China
文摘The corrosion behaviors and corresponding electrochemical impedance spectroscopy（EIS） and polarization curves of pure Mg in neutral 1.0% NaCl solution were investigated.The fractal dimension of EIS at different time was studied.The corrosion process and EIS evolution are divided into three stages.In the initial stage,EIS is composed of two overlapped capacitive arcs,the polarization resistance and charge transfer resistance increase rapidly with immersion time,and the corrosion rate decreases.Then,two well-defined capacitive arcs appear,and the charge transfer resistance and corrosion rate remain stable.After a long immersion time,inductive component appears in a low frequency range,the charge transfer resistance decreases and the corrosion rate increases with the immersion time.The fractal dimension obtained from the time records of EIS seems to be a promising tool for the analysis of corrosion morphology because of its direct relationship with the metal surface.
基金National Natural Science Foundation of China(Nos.51204147,51274175,51574206,51574207)Program for International S&T Cooperation Projects of China(No.2014DFA50320)+1 种基金Program for International S&T Cooperation Projects of Shanxi Province(No.201381017)Technological Projects of Shanxi Province(No.20150313002-3)
文摘Electrochemical impendence spectroscopy （EIS） is applied to investigate the dissolution behavior of Al-Zn alloys in 3% NaCl solution at different polarization potentials. A new reaction model is proposed, and the activation mechanism of zinc in Al-Zn alloys is achieved. There are three intermediates in the dissolution process： Znad^＋, Znad^2＋ and Alad^＋, ,of which only Zni can activate Al-Zn alloys. Most Znnd^＋ is produced by β-phase,and the alloys with 2. 3% - 3. 8% （wt） Zn dissolve rapidly. The Al-Zn alloys of heart-shaped EIS are active in 3% NaCl solution, thus EIS characteristic can be used to distinguish the activa-tion of Al-Zn alloys.
