Chemistry Commons^™

The Mechanism Of Electrocatalytic Reduction Of Oxygen On Manganese Dioxide, Yu-Liang Cao, Han-Xi Yang, Xin-Ping Ai, Li-Fen Xiao

Journal of Electrochemistry

The oxygen electroreduction on the MnO₂ electrode was investigated by analysis of the polarzation properties of oxygen reduciton and its dependence on MnO₂ discharge state, in combination with the characterization of discharge intermediate and the kinetic parameters of the oxygen reduction. Based on the experimental observation and mechanistic analysis, it was suggested that the reduction of oxygen was closely related to the discharge behaviors of MnO₂. When MnO₂ was electrochimically reduced to MnOOH, it was immediately oxidized by oxygen molecules. Thus the oxygen reduction proceeds through continuous oxidation of the discharge product of MnO_{2 …}

The Technique Of Rare-Earth Conversion Coatings On Aluminum Alloy, Jun-Tao Wang, Jian-Hua Wu, Guang-Zhang Chen

Journal of Electrochemistry

The orthogonal design was used to screen the film_forming technique on LY12 aluminum alloy using quadrivalent cerium salt, and the corrosion-resistance performance of the coating was studied. The results revealed that: after LY12 aluminum alloy was treated by cerium salt, its pitting potential shifts to positive direction while the corrosion potential slightly decreases, showing that the alloy becomes less sensitive to pitting corrosion was greatly improved, comparable to that after chromate treatment; in addition, by combining the results of electrochemical measurements with surface analysis, the mechanism of corrosion-resistance on the race-earth conversion coating of the aluminum alloy was also discussed.

Study Of Electrolyzed Pure Iron And Rrr-H Method, Wei-Min Cao, Ren-He Yin, Hui-Gen Yan, Yi-Bing Zhang, Ying-Chun Dai

Journal of Electrochemistry

The high purity electrolytic iron was made from scrap iron chips. The purity of electrolyzed pure iron was above 99.98% by chemical analysis. The resistivity was measured at 298 K and at 4.2 K under an applied longitudinal-magnetic field of 8000 e. The ratio of resistivity at 298 K to that at 4.2 K, The value of residual resistivity ratio (RRR H) roughly depended on the purity of iron. Pure iron electrolyzed on Ti substrate had very compact texture as evident by SEM.

Comparison Of Thermal Cyclic Oxidation Of The Pvd Ni-Al And Hvof-Mcraly Coatings, J-T Chang, C-H Yeh, J-L He, K-C Chen

Journal of Electrochemistry

A PVD process-cathodic arc plasma ion plating was used to deposit Ni-Al films on Inconel 600 superalloy. The oxidation behaviors of PVD Ni-Al coating and the thermal sprayed CoCrAlY coatings were revealed and compared by performing cyclic thermal oxidation test at 1100 ℃ to evaluate its feasibility. Experimental results showed that the films with different compositions of Ni₆₂Al₃₈, Ni₆₃Al₃₇ and Ni₆₉Al₃₁ could be obtained when using Ni₅₂Al₄₈, Ni₆₀Al₄₀ and Ni₇₀Al₃₀ as targets, respectively. During the cyclic thermal oxidation test, the …

Fabrication Of Scanning Micro Cl- Probe And In Situ Imaging Of Cl- At The Interface Of 2024 Al Aloy/Solution, Yu-Hua Lin, Min-Hua Shao, Rong-Gang Hu, Yan Li, Rong-Gui Du, Chang-Jian Lin

Journal of Electrochemistry

Micro combination Ag/AgCl electrode with a tip measuring tens micron in diameter was fabricated. The probe satisfied in situ imaging of Cl^- distribution at metal surface in chloride solution because of its excellent linearity between potential and Cl- concentration, rapid response, good stability and selectivity. With the aid of the home made Micro Electrode Scanning system and scanning Cl^- probe, the effect of the [Cl^-] at 2024-Al/solution interface on localized corrosion process was investigated. It was demonstated directly that Cl^- ion in solution immigrated toward, then adsorbed preferentially and accumulated at the junction between the …

An Electrochemical Prediction Method For Caustic Scc Of Fe-Cr-Ni Alloy, Chun-Bo Huang, Zhan-Peng Lv, Wu Yang

Journal of Electrochemistry

Stress corrosion cracking (SCC) of Fe-Cr-Ni alloy (alloy 800 M) in hot concentrated caustic solution was investigated by means of tests of C-rings under controlled potentials. The steady dissolution current densities (i_st) of the plate specimens and C-rings polarized potentiostatically were measured. The simplifed steady potentiostatical curves were drawn on the basis of i_st. The ratio R_PD measured from i_st and steady passive current density i p at low potentials (R_PD = i_st/i_p) was designed as a polarization dissolution susceptibility parameter. The parameter R_PD values of both plate …

Electrochemistry And Electrocatalysis Of A Novel Μ-Oxamido Copper(Ⅱ) Binuclear Complex, Gui-Lian Gao, Guo-Bao Li, Qiu-Xia Yang, Xue-Lin Wang

Journal of Electrochemistry

In this paper, the cyclic voltammetric and spectroelectrochemical behaviors of μ-oxamido Copper(Ⅱ) Binuclear Complex (deCu) in PBS were studied. Cyclic voltammograms of this complex in PBS (pH=9) exhibited two reductive peaks (E_pc1 =-0.25 V, E_pc2 = -0.50 V) at hanging mercury drop electrode(HMDE), peaks at -0.50 V and -0.25 V corresponded to the reduction of ligand and copper(Ⅱ) complex, respectively. The spectroelectrochimical experiments showed that there was a new absorption band at 440 nm, and the absorption peaks at 270 nm, 280 nm red shifted to 300 nm, 310 nm under potential of -0.75 V. It was meant …

Modeling Corrosion In Oxygen Controlled Lbe Systems With Coupling Of Chemical Kinetics And Hydrodynamics - Phase Three, Samir Moujaes, Yitung Chen

Transmutation Sciences Materials (TRP)

The proposed work will combine chemical kinetics and hydrodynamics in target and test-loop lead-bismuth eutectic (LBE) systems to model system corrosion effects. This approach will result in a predicative tool that can be validated with corrosion test data, used to systematically design tests and interpret the results, and provide guidance for optimization in LBE system designs. The task includes two subtasks. The first subtask is to try to develop the necessary predictive tools to be able to predict the levels of oxygen and corrosion products close to the boundary layer through the use of Computational Fluid Dynamics (CFD) modeling. The …

E1-E2 Interference In The Vuv Photoionization Of He, E. P. Kanter, B. Krassig, S. H. Southworth, Renaud Guillemin, Oliver Hemmers, Dennis W. Lindle, R. Wehlitz, M. Ya Amusia, L. V. Chernysheva, N. L. S. Martin

Environmental Studies Faculty Publications

We have measured the forward-backward asymmetry of photoelectron angular distributions produced in the vacuum ultraviolet photoionization of helium. This asymmetry, a consequence of the breakdown of the dipole approximation, measures the real part of the ratio of the quadrupole and dipole matrix elements. In the autoionization region, the strong energy dependence of the asymmetry permits an experimental separation of the ratio of those magnitudes from their phase difference. We experimentally determined the Fano parameters of the 2p²¹D₂ quadrupole resonance, and report improved values of the width Γ and line profile parameter q from those previously available …

Environment-Induced Degradation And Crack-Growth Studies Of Candidate Target Materials: Annual Progress Report (May 2002 – May 2003), Ajit K. Roy, Brendan O'Toole

Transmutation Sciences Materials (TRP)

As indicated in the original proposal, the primary objective of this task is to evaluate the effect of hydrogen on environment-assisted cracking of candidate target materials for applications in spallationneutron- target (SNT) systems such as accelerator production of tritium (APT) and accelerator transmutation of waste (ATW). The materials selected for evaluation and characterization are martensitic stainless steels including Alloy HT-9, Alloy EP 823 and Type 422 stainless steel. The susceptibility to stress corrosion cracking (SCC) and hydrogen embrittlement (HE) of these materials are being evaluated in aqueous environments of interest using tensile specimens under constant load and slow-strain-rate (SSR) conditions. …

Quarterly Report For The Trp Project, March–June 2003, Samir Moujaes, Yitung Chen, Kanthi Kiran Daiska, Chao Wu

Transmutation Sciences Materials (TRP)

The MTL is assumed to be a 5m long rectangular loop with a circular cross-section. Because of the non-symmetry, and due to the active participation of the secondary flows due to the elbows present in the rectangular loop model, the geometry is considered as a 3D model.

When the regions of maximum corrosion and precipitation are compared, they fall in the same zone for both the analytical and simulated models. The reason for a larger concentration flux in the case of turbulent flow than for the laminar flow can be explained by the concept of higher lateral diffusion in the …

Microstructure And Electrochemical Characteristics Of The Anodic Film Formed On Aluminum Surface, Jeng-Kuei Chang, Chi-Min Liao, Chih-Hsiung Chen, Wen-Ta Tsai

Journal of Electrochemistry

The thickness, morphology, chemical composition, and crystallinity of the anodized film formed on aluminum were examined in a transmission electron microscope (TEM). Thin foil for TEM analysis was prepared by ultramicrotomy. The relationship between the microstructure and the electrochemical characteristics of the alumina film forming on the pure aluminum was discussed in this investigation. At the forming voltage less than 100V, the anodized films formed at 85 ℃in aqueous ammonium adipate electrolyte was amorphous in nature. Although the film resistance was increased with the forming voltage, its dielectric constant was not changed significantly. As the forming voltage exceeded 100V, crystalline …

Oxidation Behavior Of Zr-Cu-Al-Ni Amorphous Alloys In Air At 300～500℃, H. H. Hsieh, W. Kai, T. G. Neih, Y. Kawamura

Journal of Electrochemistry

The oxidation behavior of the Zr- based bulk amorphous alloy (BMG; Zr-30Cu-10Al-5Ni in at.%) was studied in dry air over the temperature range 300～500 ℃. The kinetic results indicated that the amorphous alloy oxidized linearly at 300 ℃, while the parabolic oxidation was observed at 350～425 ℃, and the oxidation behavior at 500 ℃ was irregular and complicated. In general, the scales formed on the surface of the amorphous alloy were temperature-dependent, consisting of tetragonal-ZrO₂ at 300 ℃, and of mostly tetragonal-ZrO₂ as well as minor amounts of monoclinic-ZrO₂ and CuO at T ≥ 350 ℃.

Cavitation Erosion Behavior Of Ni-Al Intermetallic Coatings, J-T Chang, H-C Yeh, J-L He, K-C Chen

Journal of Electrochemistry

A cathodic arc plasma ion plating process was demonstrated to deposlt deposit Ni-Al film on AISI 1045 carbon steel to evaluate the cavitation protection. Three target materials with Ni₅₂Al₄₈, Ni₆₀Al_4o, and Ni₇₀Al₃₀ compositions were used to reveal the microstructural of coatings. Experimental results show that the nickel content in these deposits increased with the nickel contenof the target material. The major phase of deposited film was NigAl regardless of the target materials. All of the as- deposited films presented very strong adhesion and reflects their cavitation erosion behavior in …

Study Of Marine Biocorrosion Using Afm And Molecular Techniques, Herbert H.P.Fang, Lichong Xu, Tong Zhang

Journal of Electrochemistry

Biofilm is ubiquitous in nature.However,corrosin caused by biofilm is still by and large overlooked. This presentation is to demonstrate the applications of several newly developed analytical techniques in chemisrty and microbiology for the study of marine biocorrosion on steel. AFM(atomic force microscopy) was applied to investigate the initial formation mechanism of biofilm and the degree of corrosion of steel in polluted seawater. DNA/RNA-related molecular techniques were used to analyze the microbial composition corrosive biofilm. Results showed that microbial corrosion began within six days, and the corroded volume in the increased as a power function of time with an index 2.83. …

Selective Corrosion In Duplex Stainless Steel, Wen-Ta Tsai, Kuen-Ming Tsai, Chang-Jian Lin, Yan Fu

Journal of Electrochemistry

In duplex stainless steel, the two constituent phases, namely ferritic (α) and austenitic (γ) phases, have different crystal structure and chemical composition. They may thus exhibit different corrosion resistances in aqueous environment. In this investigation, an electrochemical technique with spatial resolution was employed to measure the potential difference between these two constituent phases in 2205 duplex stainless steel. Image analyzing techniques were also used to examine the preferential corrosion between α and γ phases. The experimental results showed that ferrite had a higher potential than austenite in 0.01 mol/L NaCl solution. In 2 mol/L H₂SO₄+x mol/L …

Electrochemical Monitoring On The Deactivation Of A Metallic Oxide Anode, Li-Kun Xu, Shi-Zhe Song, Ting-Yong Wang, Guang-Zhang Chen

Journal of Electrochemistry

The process of accelerated life test of an IrO₂/Ta₂O₅ coated titanium anode was monitored using cyclic voltammetry and electrochemical impedance spectroscopy. The vatiation with electrolysis time of anodic voltammetric charge Q^*, the double layer capacitance C_dl,the oxide film resistance R_f and the charge transfer resistance R_ct for oxygen evolution was measured. A deactivation mechanism was proposed based on the observation results.

Corrosion Behavior Of Reinforcing Steel In Concrete Subjected To Chloride Contamination By Eis, Rong-Gang Hu, Rong-Gui Du, Chang-Jian Lin

Journal of Electrochemistry

Electrochemical impedance spectroscopy(EIS) was employed to study the influence of chloride on the corrosion behavior of reinforcing steel in concrete. In Nyquist plot, the spectrum consists of two semicircles, indicating that the reinforced concrete system contained two time constants,one derived from electrical double layer of reinforcing steel and the other from the deposition film of concrete layer. The depressed semicircle in lower frequency featured the non-faradic behavior of the electrical double layer (EDL) deviated from idea capacitor due to diffusive effect which was attributed to the surface roughness of rebar and the inhomogenity of concrete layer. Then the EDL was …

Corrosion Behavior Of Mg1.85Mm0.15Ni Hydrogen Storage Alloy Modified By Electroless Cu In Ch3Ohâ·H2O Solutions, Hua-Bin Yang, Hai-Chang Zhang, Hua Sun, Xiao-Dan Wang, Zuo-Xiang Zhou

Journal of Electrochemistry

The corrosion behavior of the Mg_1.85Mm_0.15Ni (Mm:Ce-rich mischmetal) alloy modified by electroless Cu coating in different CH₃OH-H₂O solutions has been investigated by potentiodynamic polarization and electrochemical impedance spectroscopy. These results showed that the corrosion behavior was improved after electroless Cu. The potentiodynamic polarization and electrochemical impedance spectroscopy results showed that the alloy electrode had more promising anti-corrosion behavior after coated in a 40%CH₃OH-H₂O solution. The values of corrosion current density and electrode reaction resistance were 5.6 mA·cm^-2 (11.7 mA·cm^-2 for uncoated alloy electrode) and 22.25 Ω·cm …

A Bilayer Self-Assembled Membrane Electrode For Fluorescence And Its Electrochemical Characterization, Xiang-Ying Sun, Bin Liu, Yun-Bao Jiang

Journal of Electrochemistry

The bilayer membrane was assemblied on Au electrode by the electrostatic interaction between the fluorescence regent 1-naphthylamine diacetate acid (NADA) and DL-Cysteine. The SAMs electrode NADA/Cys/Au can be used as fluorescence and electrochemical sensor for metal ions. This paper states the electrochemical characterization of NADA/Cys/Au and SAMs' application in continous determination for Cu²⁺ and Ni²⁺.

Corrosion Prediction Of Carbon Steel In Concentrated Lithium Bromide Solutions At High Temperature Using Bp Neural Network, Nai-Bao Huang, Cheng-Hao Liang

Journal of Electrochemistry

Neutral network model has been developed for the computation of corrosion rate of carbon steel in LiBr solutions.The results indicate that the model is capable of reproducing the effects of changes in alkalinity, temperatures, LiBr and Na₂MoO₄ concentrations on the rates of general corrsion and good agreement between calculated and experimental corrosion rate is obtained. The model can be used to satisfactorily predict the corrosion rate of carbon steel in different concentrations of LiBr solutions containing different inhibitors at different temperatures. It also provides a novel method for corrosion monitoring of metals used in LiBr absorption chiller.

The Electrochemical Behaviors Of A Novel Ferrocene Alkylthiol Sams On Au Electrode, Xiao-Gang Zhang, Yan-Li Shi, Hu-Lin Li

Journal of Electrochemistry

A novel alkylthiol molecule containing ferrocene and pyridium moieties and its hydrogenated products were synthesized and subsequently assembled on Au electrode as SAMs. Cyclic voltammogram(CV) was used to investigate the structure-dependent electrochemical response of the SAMs in 0.1 mol/L HClO₄ aqueous solution.

Initial Stages Of Pd Deposition Onto Au(111) Electrodes From Pdso4, Jing Tang, Petri M., Kibler L.A., Kolb D.M.

Journal of Electrochemistry

Metal thin films have attracted considerable interest in relation to catalysis, energy, material, corrosion and environmental protection. Pd thin film is capable of proton reduction and strong hydrogen absorption, which has shown electrocatalytic activity to the oxidation of small organic molecules. In this paper, in-situ STM measurements are performed to study the deposition process and the influence of the surface structure and anion adsorption. When Pd is deposited from PdSO₄ solution on Au(111) in the UPD range, a monolayer of Pd with pseudomorphic (1×1) structure was formed on the substrate with induced (3×7) R19° SO₄^2- adsorption. With …

Recent Progress In The Research On Electrodeposition Of Composite Coatings, Xiao-Bing Liu, Xu-Cheng Wang, Yu Chen, Dan-Hong Cheng, Zu-Zhan Yu

Journal of Electrochemistry

Recent progress in the research on composite coatings prepared by electroplating technology is reviewed. The nanoscaled particles, electrocatalytic, photoactive composite coatings are emphatically discussed. The composite coatings prepared by dispersing nanoscaled particles could attain better hardness, wear resistance and corrosion resistance than those of composite coatings which prepared by adding micronscaled particles. As compared with pure metal electrode and alloy electrode, some electrocatalytic composite coatings electrode could markedly reduce the overvoltages of cathodic and anodic electrode reaction. In recent years, the electrocatalytic composite coatings which based on metal oxides and conductive polymer as matrix materials become a newest field of …

Preparation And Electrochemical Preformance Of Zn-La Alloys, Xian-Ling Meng, Hua-Bin Yang, En-Dong Yang, Xiao-Dan Wang, Hai-Chang Zhang, Jun-Hong Wang, Zuo-Xiang Zhou

Journal of Electrochemistry

Zn-La alloys were prepared by solid phase diffusion method and the effects of La on the electrochemical performance of zinc electrodes were investigated using potentiostatic polarization technique and charging/discharging cycle test. The results showed that adding La to zinc electrode remarkably suppressed the zinc dendrite, the shape of zinc electrode and zinc corrosion, and hence, markedly improved the cycle performance of zinc electrodes. The discharging capacity of the zinc electrode containing 0.5at.% La which was the optimum was still 520 mAh/g after it cycled 80s at the current of 100 mA. The XPS showed that La element mainly adhered on …

Synthesis And Electrochemical Characteristics Of Nickel-Based Complex Oxide LiANi0.78Co0.2Cd0.02O2, Rong-Zhong Yuan, Mei-Zhen Qu, Zuo-Long Yu

Journal of Electrochemistry

The nickel-based complex oxide Li_aNi_0.78Co_0.02O₂ cathode materials for lithium-ion rechargeable batteries was synthesized by the improved solid-state reaction method with LiOH·H₂O, ball-like Cd-doped Ni(OH)₂ and Co₂O₃ as raw materials. The analysis ICP-AES proved that the as-prepared compounds were near the stoichiometric form. The XRD, SEM and electrochemical characteristics testing were also carried out. The results showed that the complex cathode material Li_aNi_0.78Co_0.2Cd_0.02O₂ has layered structure, homogeneous surface distributions,uniform particles with good crystal morphology as well as stable electrochemical …

Perfluorinated Sulfonic Acid Lithium Conductivity Humidity Sensor, Hong-Feng Xu, Jing Liu, Li Wan

Journal of Electrochemistry

Treat carbon paper with 3% PTFE solution and dried in 340 ℃ for 40 minutes to enhance its intension, and level off the surface of the carbon paper with a mixture of XC-72 carbon black and PTFE solution. With those treated carbon paper as electrodes, recast Nafion thin film from 5% Nafion solution as humidity sensitive material, a solid polymer electrolyte humidity sensor was prepared on a thin PET film. Take the relative humidity data from several saturated salt solutions, the relationship between conductivity response and relative humidity was studied at different relative humidies .The results showed: when the polymer …

Conductance Properties For Electrolyte Of Lithium Ion Battery At Low Temperature, Jing-Li Han, Yan-Mei Yu, Jian Chen, Chun-Tong Wang

Journal of Electrochemistry

The system of LiPF₆-ethylene carbonate (EC)-methy1 acetate (MA) was studied. The conductivities of this system were measured under various composition and various salt concentrations at temperature range of 20～-50 ℃. The optimum composition of this system was selected. The tests of cyclic voltammography and charge-discharge were carried out. This system was compared with commercial electrolyte solution.

Effect Of Scn- On The Transition Current Of Zn During The Electrodeposition Zn-Co Alloys, Ren-He Yin, Wei-Min Cao, Zheng-Hua Fang

Journal of Electrochemistry

For co-deposition of Zn-Co alloys at sufphate baths with micro-concentration of SCN^- the transition current of Zn was found with the deposition process changing from normal Co-deposition to anomalous co-deposition, and the value of transition current increased with increasing SCN^- concentration, but decreased with increasing value of pH. The existence of SCN^- decreases the evolution overpotential of Co metal, but has no effects on the evolution overpotential of Zn metal and H₂.

Stress Corrosion Cracking Of Type 422 Stainless Steel For Applications In Spallation-Neutron-Target Systems, Ramprashad Prabhakaran

Transmutation Sciences Materials (TRP)

Introduction

• This research program is aimed at evaluating different types of environment-induced degradation of candidate target materials for applications in transmutation of spent nuclear fuels (SNF).

• Transmutation refers to the elimination of long-lived actinides and fission products from SNF.

Objectives

• Evaluate susceptibility of candidate target materials to stress corrosion cracking (SCC) and localized corrosion (pitting and crevice) in neutral and acidic aqueous environments at ambient and elevated temperatures

• Determine the extent and morphology of cracking in tested materials as functions of experimental and environmental variables including pH, temperature, loading conditions and specimen geometry

• Develop mechanistic …