Microstructure and Electrode Characteristics of Ti-V-Cu-Cr-Ni Metal Hydride Electrode Alloy

2012 ◽  
Vol 512-515 ◽  
pp. 1933-1936
Author(s):  
Yu Qing Qiao ◽  
Min Shou Zhao ◽  
Li Min Wang
Keyword(s):  
Metal Hydride ◽  
Electrochemical Impedance ◽  
Secondary Phase ◽  
Charge Transfer Resistance ◽  
Solid Solution Phase ◽  
Transfer Resistance ◽  
Metal Hydride Electrode ◽  
Eis Measurements ◽  
Increasing Temperature ◽  
Electrode Characteristics

Microstructure and electrode characteristics of Ti-V-Cu-Cr-Ni metal hydride electrode alloy have been investigated by XRD, FESEM-EDS and EIS measurements. The result shows that the alloy is mainly composed of V-based solid solution phase with body-centered-cubic structure and TiNi-based secondary phase. The discharge capacity increases with increasing temperature in a wider temperature region from 303 K to 343 K. The result of electrochemical impedance spectrometry indicates that the charge transfer resistance decreases with increasing temperature, while the exchange current density in the bulk of the alloy increase with increasing temperature.

Microstructure and some Dynamic Performances of Ti-V-Pd-Cr-Ni Metal Hydride Electrode Alloy

2012 ◽  
Vol 512-515 ◽  
pp. 1937-1940
Author(s):  
Xian Wen Zeng ◽  
Yu Qing Qiao ◽  
Min Shou Zhao
Keyword(s):  
Temperature Region ◽  
Metal Hydride ◽  
Electrochemical Impedance ◽  
Secondary Phase ◽  
Dynamic Parameters ◽  
Metal Hydride Electrode ◽  
Dynamic Performances ◽  
Eis Measurements ◽  
Increasing Temperature ◽  
Bcc Phase

Microstructure and Some Dynamic Parameters of Ti-V-Pd-Cr-Ni metal hydride electrode alloy have been investigated by XRD, FESEM and EIS measurements. The result shows that the alloy is mainly composed of bcc phase and TiNi-based secondary phase. The discharge capacity increases with increasing temperature in a wider temperature region from 303 K to 343 K. The result of electrochemical impedance spectrometry indicates that RT decreases with increasing temperature, which is 2.392Ω, 0.531Ω and 0.156Ω at 303K, 323K and 343K, respectively. However, I0 increases with increasing temperature, which is 72.76 mA g-1, 327.75 mA g-1 and 1262.88 mA g-1 at 303K, 323K and 343K, respectively.

scholarly journals The Effect of Achyranthes aspera Extracts on Mild Steel Corrosion in Industrial Water Medium

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Chikkur B. Pradeep Kumar ◽  
Kikkeri N. Mohana
Keyword(s):  
Mild Steel ◽  
Electrochemical Impedance ◽  
Electrochemical Techniques ◽  
Steel Corrosion ◽  
Charge Transfer Resistance ◽  
Water Medium ◽  
Industrial Water ◽  
Transfer Resistance ◽  
Achyranthes Aspera ◽  
Eis Measurements

Achyranthes aspera (AA) extracts were studied as corrosion inhibitor for mild steel (MS) in industrial water medium using mass loss and electrochemical techniques. The results of the study revealed that AA extracts inhibit MS corrosion through adsorption process following Langmuir adsorption isotherm model. The protection efficiency increased with increase in inhibitor concentration and decreased with temperature. The electrochemical impedance spectroscopy (EIS) measurements showed that the charge transfer resistance increases with increase in the concentration of AA extracts. The polarization curves obtained indicate that AA extracts act as mixed type of inhibitor. Scanning electron microscopy (SEM) was used to analyze the surface adsorbed film.

Evaluation of corrosion inhibition and adsorption behavior of Thymuszygis subsp. gracilis volatile compounds on mild steel surface in 1 m HCl

2020 ◽  
Vol 38 (2) ◽  
pp. 137-149
Author(s):  
Mohamed Ouknin ◽  
Abderrahmane Romane ◽  
Jean-Pierre Ponthiaux ◽  
Jean Costa ◽  
Lhou Majidi
Keyword(s):  
Mild Steel ◽  
Electrochemical Impedance ◽  
Aggressive Medium ◽  
Three Dimensional ◽  
Steel Corrosion ◽  
Charge Transfer Resistance ◽  
Infrared Analysis ◽  
Transfer Resistance ◽  
3D Profilometry ◽  
Eis Measurements

AbstractThe inhibition effect of Thymus zygis subsp. gracilis (TZ) on mild steel corrosion in 1 m hydrochloric acid has been investigated by weight loss measurements, surface analysis [scanning electron microscopy (SEM)-energy-dispersive X-ray (EDX), three-dimensional (3D) profilometry, and Fourier transform infrared analysis], potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS). Gravimetric results indicate that TZ exhibits good inhibition efficiency of 80.40% attained at 3 g/l. Polarization measurements show that the studied inhibitor is a mixed type. EIS measurements revealed that the charge transfer resistance increases with increasing concentration of TZ, which suggests a Langmuir adsorption isotherm model. Based on SEM-EDX and 3D profilometry, it appears that the surface is remarkably improved in the presence of TZ oil compared to that exposed to the acid medium without TZ oil. From the obtained results, it can be concluded that this oil is a new natural substance that can be used against material corrosion in aggressive medium.

Corrosion Analysis of Reinforcing Steels in Mortar for Nuclear Facilities

2009 ◽  
Author(s):  
Toshiyasu Nishimura
Keyword(s):  
Electrochemical Impedance ◽  
Initial Period ◽  
Charge Transfer Resistance ◽  
Ion Concentration ◽  
Reinforcing Steel ◽  
Nuclear Facilities ◽  
Good Correspondence ◽  
Transfer Resistance ◽  
Eis Measurements ◽  
Cover Thickness

It is important to estimate the corrosion of reinforcing steel in mortar facilities, because the nuclear plants are located near the sea side. In the case of environmental factors in mortar, the Cl ion concentration and pH were monitored by inserting microelectrodes into artificial pores in the mortar. At the same time, the corrosion behavior of the reinforcing steel was investigated by EIS (electrochemical impedance spectroscopy). In the EIS measurements of the reinforcing steel, diffusion behavior was confirmed in the initial period, but diffusion could no longer be observed after 35 day. In comparison with a 10mm cover thickness, a 20mm cover thickness showed a higher impedance behavior. The Cl ion concentration in the mortar was obtained using Ag/AgCl microelectrodes, showing that this behavior is generally controlled by diffusion. When the diffusion equation was used in this work, the diffusion coefficient (Dc) showed a high value of Dc = 2×10−4 mm2/sec. Similarly, the pH in the mortar was obtained using W/WOx microelectrodes. With a 20mm cover thickness, pH was limited to approximately pH11, but with a 10mm cover thickness, pH continued to decrease to around pH9.5. The latter phenomenon was considered to be the result of neutralization by penetration of the immersion solution from the surface. Based on the results of monitoring with the microelectrodes, solutions simulating those in the pores in mortar were prepared and used in EIS measurements. The charge transfer resistance Rct in the simulated solutions showed good correspondence with the impedance in the low frequency region (2mHz) in the actual mortar. This is attributed to the fact that the corrosion of reinforcing steel was controlled by the solution conditions (mainly Cl concentration and pH) in the pores in mortar. If these solution conditions (Cl concentration, pH) exceed threshold values, it was found that the passivation film is destroyed, resulting in high corrosion.

scholarly journals Initial Stages of AZ31B Magnesium Alloy Degradation in Ringer′s Solution: Interpretation of EIS, Mass Loss, Hydrogen Evolution Data and Scanning Electron Microscopy Observations

Metals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 933 ◽  
Author(s):  
Lucien Veleva ◽  
Mareny Guadalupe Fernández-Olaya ◽  
Sebastián Feliu
Keyword(s):  
Magnesium Alloy ◽  
Hydrogen Evolution ◽  
Electrochemical Impedance ◽  
Corrosion Current ◽  
Charge Transfer Resistance ◽  
Uniform Corrosion ◽  
Transfer Resistance ◽  
Az31b Magnesium Alloy ◽  
Current Densities ◽  
Eis Measurements

The initial stages of corrosion of AZ31B magnesium alloy, immersed in Ringer′s solution at 37 °C body temperature for four days, have been evaluated by independent gravimetric and chemical methods and through electrochemical impedance spectroscopy (EIS) measurements. The corrosion current densities estimated by hydrogen evolution are in good agreement with the time-integrated reciprocal charge transfer resistance values estimated by EIS. The change in the inductive behavior has been correlated with difference in the chemical composition of corrosion layers. At the shorter immersion of 2 days, EDS analysis of cross section of the uniform corrosion layer detected Cl and Al elements, perhaps as formed aluminum oxychlorides salts.

Synthesis of LiMn0.7Fe0.3PO4/C Composite Cathode Materials for Lithium-Ion Batteries

2013 ◽  
Vol 634-638 ◽  
pp. 2617-2620
Author(s):  
Na Chi ◽  
Jian Gang Li ◽  
Lei Wang ◽  
Jie Si Fu
Keyword(s):  
Electrochemical Performance ◽  
Electrochemical Impedance ◽  
Lithium Ion ◽  
Solid State Reaction Method ◽  
Composite Cathode ◽  
Charge Transfer Resistance ◽  
Electrochemical Impedance Spectra ◽  
Transfer Resistance ◽  
Cation Order ◽  
Increasing Temperature

LiMn0.7Fe0.3PO4/C composite cathode material was prepared by using a solid state reaction method. The effects of annealing temperatures on the structural and electrochemical performance of LiMn0.7Fe0.3PO4/C were investigated by using X-ray diffraction (XRD), scanning electron microscope (SEM), charge–discharge tests and electrochemical impedance spectra (EIS). The results showed that all of samples have pure ordered olivine phase with orthorhombic Pnma structure. The electrochemical performance of LiMn0.7Fe0.3PO4/C can be improved remarkably with increasing temperature from 550oC to 650 oC due to increased crystallization, cation-order and decreased charge transfer resistance. However, increase temperature to 700 oC leads to bigger crystal particle size and decreased cation-order, thus higher resistance and deteriorated electrochemical properties. The sample prepared at optimized temperature of 650 oC presents a remarkable improved electrochemical performance. It delivers an initial capacity of 125.1 mAhg-1 at 0.2C, 95 mAhg-1 at 5C, and a capacity retention of 98.0% after 30 cycles.

scholarly journals Enrichment-Free Rapid Detection of Phthalates in Chinese Liquor with Electrochemical Impedance Spectroscopy

Sensors ◽  
2020 ◽  
Vol 20 (3) ◽  
pp. 901
Author(s):  
Xinyue Jiang ◽  
Yuqun Xie ◽  
Duanji Wan ◽  
Fuping Zheng ◽  
Jun Wang
Keyword(s):  
Electrochemical Impedance Spectroscopy ◽  
Impedance Spectroscopy ◽  
Metal Ion ◽  
Electrochemical Impedance ◽  
Charge Transfer Resistance ◽  
Transfer Resistance ◽  
Faradaic Impedance ◽  
Chinese Liquor ◽  
Non Invasive ◽  
Eis Measurements

A non-invasive real-time detection technique for phthalates in Chinese liquor is proposed in this paper. This method is based on the measurement of Faradaic impedance in the presence of a redox probe, [Fe(CN)6]3−/4−, upon the absorption of phthalates to the graphene electrode surface. This absorption activity is according to the π–π stacking interactions between phthalates and the graphene working electrode which allows direct sampling and analyte preconcentration. The absorption of phthalates retards the interfacial electron-transfer kinetics and increases the charge-transfer resistance (Rct). Numerical values of Rct were extracted from a simulation of electrochemical impedance spectroscopy (EIS) spectra with the corresponding equivalent circuit. Cathodic polarization was employed prior to EIS measurements to effectively eliminate the metal ion interference. The results yielded a detection limit of 0.024 ng/L for diethyl phthalate (DEP) with a linear range from 2.22 ng to 1.11 µg. These results indicate a possibility of developing a household sensor for phthalate determination in Chinese liquor.

scholarly journals Impedance analysis of ZnO nanowire coated dry EEG electrodes

2017 ◽  
Vol 3 (1) ◽  
pp. 44 ◽  
Author(s):  
Jiamin Wu ◽  
Wenyan Jia ◽  
Chengkun Xu ◽  
Di Gao ◽  
Mingui Sun
Keyword(s):  
Electrochemical Impedance ◽  
Equivalent Circuit Model ◽  
Impedance Analysis ◽  
Polyester Fabric ◽  
Charge Transfer Resistance ◽  
Zno Nanowire ◽  
Test Bed ◽  
Transfer Resistance ◽  
Eis Measurements ◽  
Electroencephalogram Eeg

The electrochemical impedance of a novel dry electroencephalogram (EEG) electrode after surface modification (i.e., sputtered with gold, coated with ZnO nanowires) is investigated in this study. To avoid the discomfort caused by repetitive testing on human, a skin-mimic sandwich structure, comprised of a highly porous polyester fabric membrane and two thin silicone films, is fabricated as a test bed. Electrochemical impedance spectroscopy (EIS) measurements are conducted to further understand the properties of the electrode-electrolyte interface when the electrode is installed on this test bed. An equivalent circuit model with a constant phase element (CPE) is used to fit the EIS data. Our results show that the modeled EIS data are in good agreement with the experimental data. It has also been found that the charge transfer resistance decreases from 349 Ω cm2 for the bare electrode to 256 Ω cm2 for the gold-coated electrode and further decreases to 167 Ω cm2 for the gold coated short ZnO nanowire electrode. The lower impedance value will definitely help improve the signal when such electrode is used to record electrophysiological data. 

CORROSION PROTECTION OF AZ91D Mg ALLOY COATING WITH MICRO-ARC OXIDATION FILM EVALUATED BY IMMERSION AND ELECTROCHEMICAL TESTS

2005 ◽  
Vol 12 (02) ◽  
pp. 279-287 ◽  
Author(s):  
X. P. ZHANG ◽  
G. CHEN
Keyword(s):  
Corrosion Protection ◽  
Electrochemical Impedance ◽  
Alloy Coating ◽  
Charge Transfer Resistance ◽  
Mg Alloy ◽  
Nacl Solution ◽  
Transfer Resistance ◽  
Electrochemical Tests ◽  
Micro Arc Oxidation ◽  
Eis Measurements

This paper describes the preliminary results of corrosion protection of AZ91D Mg alloy coated with a micro-arc oxidation (MAO) coating. The corrosion behavior of coated substrates was evaluated by means of immersion and electrochemical tests in 5 wt.% NaCl solution. The immersions tests include weight loss measurement after full or partial immersion with the whole coat and full immersion with the damaged coat. The electrochemical tests include polarization curves and electrochemical impedance spectroscopy (EIS) measurements. The results of immersion and electrochemical tests show that micro-arc oxidation (MAO) surface treatment can significantly improve the corrosion resistance of the AZ91D Mg alloy in 5% NaCl solution, and the corrosion protection effect of the MAO coating is not sensitive to pores or cracks in the coating. The charge transfer resistance R ct , increases from about 1.669Ωcm2 for the uncoated alloy to about 1113Ωcm2 after being coated with MAO coat.

Improvement of Ti/RuO2–IrO2 Anode Lifetime and Electrocatalytical Properties by Using an Eco-Friendly Thermal Decomposition Method Using Polyvinyl Alcohol as Solvent

2019 ◽  
Author(s):  
Charlys Bezerra ◽  
Géssica Santos ◽  
Marilia Pupo ◽  
Maria Gomes ◽  
Ronaldo Silva ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Polyvinyl Alcohol ◽  
High Efficiency ◽  
Electrochemical Impedance ◽  
Pechini Method ◽  
Low Cost ◽  
Charge Transfer Resistance ◽  
Transfer Resistance ◽  
Calcination Temperatures ◽  
Service Lifetime

<p>Electrochemical oxidation processes are promising solutions for wastewater treatment due to their high efficiency, easy control and versatility. Mixed metal oxides (MMO) anodes are particularly attractive due to their low cost and specific catalytic properties. Here, we propose an innovative thermal decomposition methodology using <a>polyvinyl alcohol (PVA)</a> as a solvent to prepare Ti/RuO<sub>2</sub>–IrO<sub>2</sub> anodes. Comparative anodes were prepared by conventional method employing a polymeric precursor solvent (Pechini method). The calcination temperatures studied were 300, 400 and 500 °C. The physical characterisation of all materials was performed by X-ray diffraction and scanning electron microscopy coupled with energy dispersive spectroscopy, while electrochemical characterisation was done by cyclic voltammetry, accelerated service lifetime and electrochemical impedance spectroscopy. Both RuO<sub>2</sub> and IrO<sub>2</sub> have rutile-type structures for all anodes. Rougher and more compact surfaces are formed for the anodes prepared using PVA. Amongst temperatures studied, 300 °C using PVA as solvent is the most suitable one to produce anodes with expressive increase in voltammetric charge (250%) and accelerated service lifetime (4.3 times longer) besides reducing charge-transfer resistance (8 times lower). Moreover, the electrocatalytic activity of the anodes synthesised with PVA toward the Reactive Blue 21 dye removal in chloride medium (100 % in 30 min) is higher than that prepared by Pechini method (60 min). Additionally, the removal total organic carbon point out improved mineralisation potential of PVA anodes. Finally, this study reports a novel methodology using PVA as solvent to synthesise Ti/RuO<sub>2</sub>–IrO<sub>2</sub> anodes with improved properties that can be further extended to synthesise other MMO compositions.</p>

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