Engineering Science and Materials Commons^™

Stress Corrosion Cracking And Hydrogen Embrittlement Of Martensitic Alloy Ep-823, Mohammad K. Hossain

UNLV Theses, Dissertations, Professional Papers, and Capstones

This investigation is focused on the evaluation of stress corrosion cracking (SCC), localized corrosion, and hydrogen embrittlement (HE) susceptibility of martensitic Alloy EP-823 in neutral and acidic solutions at ambient and elevated temperatures. While no failures were observed in smooth specimens in the neutral solution, failures were noticed in the 90°C acidic solution at constant-load (CL) leading to a threshold stress (O'_th) of 102 ksi. The presence of a notch reduced the O'_th value to 91 ksi in a similar environment. The ductility (%El and %RA), time-to-failure (TTF), and true failure stress (O'_r) were gradually …

Stress Corrosion Cracking Resistance Of Martensitic Stainless Steels For Transmutation Applications, Phani P. Gudipati

UNLV Theses, Dissertations, Professional Papers, and Capstones

The susceptibility of Alloy EP-823 to stress corrosion cracking has been evaluated using smooth and notched cylindrical specimens in neutral and acidic solutions at ambient and elevated temperatures using constant load and slow strain rate testing (SSR) techniques. C-ring and U-bend specimens have also been tested in the acidic solution. The effect of hydrogen on the cracking susceptibility has been evaluated under controlled cathodic potential. While no failures were observed with smooth specimens at constant load, the notched specimens showed failure. The SSR test results indicate that the true failure stress (o'_f), time to failure and ductility parameters …

Biomimetic Actuators: Where Technology And Cell Biology Merge [Review Article], Michael Knoblauch, Winfried Peters

Winfried S. Peters

Electrochemical Behaviours Of Hemoglobin-Ddab-Modified Powder Microelectrode And The Application Of The Powder Microelectrode In Determination Of Nitric Oxide, Zhi-Mou Guo, Huan Liu, Jian Chen, Wen-Ting Zhang

Journal of Electrochemistry

The electrochemical behaviours of DDAB-Hb-PME were studied in this paper. The (apparent) surface concentration of Hb was enhanced greatly by using the powder microelectrode (technique). NO reacts with Hb and absorbs on the surface of the modified carbon powder. Therefore, the output of the electrode was enhanced greatly by employing PME with higher reaction surface (area). The sensitivity of DDAB-Hb-PME is 3.1 mA/μmol·L~(-1)·cm~(2), which is much larger than the values obtained with the traditional electrodes. The detection limit is 9 nmol·L~(-1) and the linear response range is 9～100 nmol·L~(-1).

Lico_(X)Ni_(1-X)O_2 Cathode Materials Prepared By Electrolysis Of Co And Ni, Jin-Ping Wei, Xin Sun, Xiao-Yu Wang, Xi-Kui Bian, Jin-Ling Zhai, Yan-Jie Yan-Jie

Journal of Electrochemistry

A new electrolytic method was developed to prepare LiCo_(x)Ni_(1-x)O_2 as a cathode material of lithium-ion battery. Contrary to the traditional method, electrolytic method is a potential method with simple process to industrialization and no pollution. Metal cobalt and nickel were electrolysed in parallel to prepare the precursor of Co_( x )Ni_(1- x )(OH)_2.Different compositional precursors could be conveniently prepared by changing electrolytic current. The LiCo_(0.3)Ni_(0.7)O_2 cathode prepared by this method was found favorable charge-discharge and cycle properties. For the LiCo_(0.3)Ni_(0.7)O_(2 )cathode material, the discharge capacities in the 1st and 50th cycles were 163 mAh/g and 140 mAh/g with charge retention …

The Investigation Of Bafesi/C Alloy Composite As Anode Materials For Li-Ion Battery, Rui-Xiang Feng, Hua Dong, Xin-Ping Ai, Han-Xi Yang

Journal of Electrochemistry

A novel BaFeSi/C composite was prepared by mechanical ball milling, and lithium insertion reactions on the composite electrode were investigated by cyclic voltammetry ,charge-discharge measurements, XRD and XPS spectroscopy. It is demonstrated that the capacity retention with indiscernible capacity decas during charge-discharge cycling. The improved cycling ability of the composite is suggested from a cooperative action by inactive FeSi_(2 )and BaSi_2 matrix and outer graphite shell, which both buffer the volumetric changes of the active Si phase and provide a good connection for electronic and ionic conduction during lithium insertion and extraction processes.

Electrocatalytic Performances Of Carbon Nanotube Air Electrode For Oxygen Reduction, Feng-Ming Zhao, Chun-An Ma

Journal of Electrochemistry

The air electrodes with different mass ratio of Pt/active carbon or carbon nanotube as catalyst layer material have been prepared. The electrocatalytic performances for oxygen reduction were evaluated by means of polarization curve and electrochemical impedance spectroscopy (EIS). The results disclosed that carbon nanotubes dealt with nitric acid in the catalyst layer had been improved obviously on the electrocatalytic activity. After the surface of carbon nanotube was oxygenated and aggraded with platinum, the catalyst had obviously effects on the electrocatalytic activity. The air electrode with the mass ratio of active carbon to Pt/carbon nanotube in 4∶1 showed better electrocatalytic activity, …

Electrochemical Investigations On Pitting Susceptibility Of Iron-Based Alloy, Wei-Shan Li, Hong-Yu Chen, Zhong-Zhi Yuan, Hong Li, Qi-Ming Huang, Dong-Sheng Lv

Journal of Electrochemistry

The formation process of passive film on iron and electronic properties and pitting susceptibility of an iron-based alloy are investigated by using linear potential sweep, alternative current impedance and electrochemical nose technologies. The relationship between reciprocal square capacitance and potential following the Mott-Schottky behavior is limited at a narrow rang of low potentials. At higher potentials, linear relationship between reciprocal capacitance and potential is obtained, which is ascribed to the increasing thickness of the passive film with potential. The donor density of the passive film is influenced by the formation potential of the film, passivator and microstructure. The decrease in …

Preparation And Electrochemical Magnesium Insertion Behaviors Of Mgv_2o_6, Hua-Tang Yuan, Li-Fang Jiao, Jian-Sheng Cao, Xiu-Sheng Liu, Ming Zhao, Yong-Mei Wang

Journal of Electrochemistry

MgV_2O_6was synthesized by conventional solid-state reaction from MgO and V_2O_(5)as starting materials. X-Ray diffraction analysis showed that the prepared sample belongs to the monoclinic structure. Electrochemical magnesium insertion from aprotic electrolytes such as organomagnesium halides into this host was found possible and exhibited charge/discharge circulation.

Studies On The Electrochemical Preparation And Electrochemical Properties Of Conducting Polymers——Brief Introduction To The Research Work Of Electrochemistry Of Conducting Polymers In Cas Key Laboratory Of Organic Solids(I), Yong-Fange Academy Of Sciences Li

Journal of Electrochemistry

Conducting polymers have drawn much attention since the discovery of conducting polyacetylene in 1977, due to the novelty and curiosity of their structure and properties as well as their promising applications in many aspects. Among the studies of conducting polymers, the electrochemical preparation and electrochemical properties of conducting polymers are of special importance, because the electropolymerization is a main method for preparing conducting polymer films and the electrochemical properties are the basis for their applications in the fields of electrode materials for batteries, electrocatalysis, electrochromic display, etc. We are one of the earliest research groups in the world to perform …

Preparation And Photo-Catalyst Properties Of The Α-Fe_2o_3-Tio_2 Films On Sodium Alginate Polymer, Li-Qin Chen, Huai-Zhen Zhong, Ri-Yao Chen, Xi Zheng, Zhen Chen

Journal of Electrochemistry

Three new nano thin films of α-Fe_2O_(3)、TiO_2 and α-Fe_2O_(3)-TiO_2 by doping their powder with sodium alginate polymer were prepared. Surface structure and catalytic activities of the films were characterized by FTIR、XRD、PL、TEM and I-V techniques. The results of UV-visible absorption showed that the methylene blue was mineralized in aqueous of α-Fe_2O_(3)/SA、TiO_2/SA and (α-(Fe_2O_(3)))-TiO_2 /SA upon radiation with ultra violet light. α-Fe_2O_(3) enhanced their photo-decolorized-activities by doping 15% TiO_2.

Applications Of New Activated Carbon Meterials In The Electric Double-Layer Capacitor, Jian-Jun Zhang

Journal of Electrochemistry

A new type activated carbon whose precursor was coconut shell could be obtained using specific physics-chemistry activation, and the activated carbon was applied as the material of electrode in EDLC(electrical double-layer capacitor),which had a large specific capacitance,and could charge and discharged in some large currents. Carbon dioxide and acid were used to modify carbon,and the effects of post-treatment on surface area and pore volume were investigated. A moulding method which has influence on some properties of carbon electrode with PTFE additive was researched in the paper.

Improvement And Its Mechanism Of Storage Performance Of Ni-Mh Battery, Xiao-Feng Li

Journal of Electrochemistry

The storage performance of nickel-metal-hydride (Ni-MH) battery was studied by using galvanostatic charge-discharge and cyclic voltammetry. The experimental results indicated that CoOOH could not be completely restored after its being thoroughly reduced at lower potential, which might weaken electric conduction network in the positive electrode and result in fading of electrochemical properties of Ni-MH battery. Addition of nickel powder as a conductive agent into the positive electrode was beneficial to the capacity recovery after storage.

Effect Of Fe~(3+) Dopen Of Titanium Dioxide Film On Absorption Spectra And Photo Catalysis, Mei-Qun Xiao, Jia-Nian Shen, Moucheng Li, Peng-Fei Wu, Dong Liu, Yu-Juan Zhang

Journal of Electrochemistry

Photo-catalytic titanium dioxide film in nano crystalline has been prepared by electrochemical oxidation process and adding different amount of ferric ion into the electrolyte during the anodic oxidation.The effects of Fe~(3+) dopen on absorption spectra and photo-catalytic of the titanium dioxide films have been studied. It shows that the Fe~(3+) dopen caused the red shife of the absorption edge for the incoming light and exhibited the improved photocatalytic reactivity.

Study On Mass Transport In Liquid Layer Adjacent To The Electrode Through Transmission Vop-Spectroellipsometry, Wei Zhu, Yangyu-Ru Yangyu-Ru, Zong-Qing Huang

Journal of Electrochemistry

In electrochemical system, the mass transport process in liquid layer adjacent to electrode is studied through theoretical analysis only.The diffusion process can be analyzed theoretically by Fick's law for homogeneous media. Up to now, none of satisfied experimental method has been reported for studying mass transport of a whole process in liquid media yet. This paper described the experimental approach to explore mass transport in electrochemical system by transmission Vop-spectroellipsometry briefly.

Environmental Effects On Corrosion Properties Of Alloy 22, K. S. Raja, L. G. Mcmillion, Shantanu A. Namjoshi, Paige Russel, Raymond E. Keeler, Amy J. Smiecinski

Publications (YM)

During the regulatory life of the Yucca Mountain High Level Nuclear Waste (HLNW) repository the primary engineered barrier that is to prevent release of radioactive material into the environment is proposed to be a Corrosion-Resistant Material (CRM) outer shell covering the Waste Package (WP) container. The current selection for the CRM is Alloy 22 (UNS N06022), a Ni-Cr-Mo-W-Fe alloy. Alloy 22 forms a defective chromic oxide passive film which results in excellent corrosion resistance; the presence of molybdenum in Alloy 22 offers corrosion resistance in reducing environments as well as oxidizing environments.

Surface Structure Of Alkylsilylated Hzsm-5 As Phase-Boundary Catalyst, Hadi Nur, Yun Hau Ng, Mohd Nazlan Mohd Muhid, Halimaton Hamdan

Yun Hau Ng

The need for cleaner environment concerns motivates the development of more efficient catalytic system. Based on this consideration, recently a novel catalyst named "Phase-boundary catalyst", a bimodal amphiphilic solid catalyst, was proposed. It was demonstrated that the catalytic system containing phase-boundary catalyst required neither stirring to make an emulsion nor addition of a co-solvent to make a homogeneous solution to drive the reaction. The driving force that has prompted this paper is to investigate the surface structure of alkylsilylated HZSM-5 as phase-boundary catalyst. Temperature Programmed Desorption (TPD) of ammonia and, 13C and 29Si MAS NMR spectroscopy were used to elucidate …

Phase Stability And Segregation In Alloy 22 Base Metal And Weldments, Jeffrey Lacombe, Shantanu A. Namjoshi, Paige Russel, Raymond E. Keeler, Amy J. Smiecinski

Publications (YM)

The current design of the waste disposal containers relies heavily on encasement in a multi-layered container, featuring a corrosion barrier of Alloy 22, a Ni-Cr-Mo-W based alloy with excellent corrosion resistance over a wide range of conditions. The fundamental concern from the perspective of the Yucca Mountain Project, however, is the inherent uncertainty in the (very) long-term stability of the base metal and welds. Should the properties of the selected materials change over the long service life of the waste packages, it is conceivable that the desired performance characteristics (such as corrosion reistance) will become compromised, leading to premature failure …

The Electrochemical Behavior And Determination Of Gsh At The Powder Microelectrode, Jian Chen, Zhong-Yu He, Chuansin Cha, Huan Liu

Journal of Electrochemistry

In this paper, the electrochemical behavior of GSH at the surface of platinum(Pt) electrode, glass carbon(GC) electrode and acetylene black packed powder microelectrode (AB-PME) was studied. It was found that the electrochemical oxidations of GSH at both Pt and GC electrode were highly irreversible. No current peak or current plateau could be observed from the CV curves. The direct electro-oxidation of GSH at carbon surface was achieved by using the PME technique.In this case, the apparent reversibility of GSH oxidation was enhanced significatly .The overpotential of GSH oxidation was reduced to 0.5 V at the surface of AB-PME compared with …

Nucleation And Crystal Growth Of Pt Electrodeposition On Poly Crystal Au Microdisc Electrode, Zhi-Yong Tao, Pei-Fang Liu

Journal of Electrochemistry

Based on the Fleischmann's model of nucleation and crystal growth for electrodeposition combined with the Barradas-Bosco's adsorption-nucleation model for electrochemical phase formation, the chronoamperometry was well fitted for Pt deposition on polycrystalline Au micro disc electrodes (30 μm in diameter) in different H_(2)PtCl_(6) concentrations at different over-potentials. The initial stage of Pt deposition in dilute H_(2)PtCl_(6) could be interpreted by the model of H_(2)PtCl_(6 ) adsorption combined with instantaneous nucleation and two-dimensional cylindrical growth. The rate constant of the two-dimensional growth increased linearly with overpotential. Then the deposit grew layer by layer and the rate constant increased non-linearly with overpotential. …

Preparation And Electrochemical Performance Of New Composite Seperators For Lithium-Ion Batteries, Hu Cheng, Hong-Yan Du, Yong Yang

Journal of Electrochemistry

New composite seperators for lithium ion batteries were prepared by coating PEO mixed with nanosize SiO_(2)onto microporous polypropylene(PP) seperators. Highly conductive electrolytes were prepared by soaking them in an electrolyte solution. With these composite separators, the lithium ion cell consisting of Li anode and LiNi_(0.8)Co_(0.2)O_(2)cathode were assembled. The high initial discharge capacity and good capacity retention were obtained through the cell.

Effects Of Barium On The Performance Of Secondary Alkaline Zinc Electrode, Yi Zheng, Jian-Ming Wang

Journal of Electrochemistry

The active material of secondary alkaline zinc electrode with barium additives was prepared by a chemical reaction method and characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The electrochemical performance of various pasted Zn electrodes was investigated by cyclic voltammetry, charge/discharge method and electrochemical impedance spectra (EIS) technology. The addition of barium can synthesize a compound barium zincate with the molecular structure of BaZn(OH)_(4)· xH_(2)O and improve the discharge performance. The EIS of the various Zn electrodes showed two time constants besides diffusion impedance, including a state variable representing the covering degree of discharge products on the electrode …

Solid State Synthesis And Electrocatalysis Of Pt/Moo_3 For The Oxidation Of Methanol, Wang Qing

Journal of Electrochemistry

The electrocatalyst, Pt/MoO_(3) synthesized by solid state reaction, was used for the oxidation of methanol in direct methanol fuel cells. The X-Ray diffraction and cyclic voltammetry were employed to investigate the performance of the material. It was shown that the typical diffraction peaks for Pt appeared in XRD. And a good electrocatalysis for methanol oxidation was observed. The peak potential of the methanol oxidation appeared at ca. 0.63V(vs.SCE) and the peak current density for the oxidation was 78.1 mA cm~(-2) .

Synthesis And Electrochemical Behavior Of Layered-Structure Limn_(1-X)Cr_Xo_2, Jie Xiao, Hui Zhan, Yun-Hong Zhou

Journal of Electrochemistry

The Layered-structure LiMn_(1-x)Cr_xO_(2 )(x=0,0.15) solid solution has been prepared by the rheological phase method. From the XRD results, undoped LiMnO_(2) crystallized almost entirely in the orthorhombic phase while the structure of LiMn_(0.85)Cr_(0.15)O_(2) belongs to monoclinic phase. TEM investigation shows that the final powder product consists of ultrafine spherical particles which are distributed homogeneously, with the average diameter ranging from 60 to 300nm. The initial discharge capacity of LiMn_(0.85)Cr_(0.15)O_(2) is much higher than that of undoped LiMnO_(2). After 40 cycles, the capacity retention for m-LiMn_(0.85)Cr_(0.15)O_(2 )is 94% at the current rate of 50mA/g under room temperature. The results of electrochemistry tests …

Lithium Insertion Into Tio_2(B) Nanobelts Synthesized By The "Soft Chemical" Method, Cha-Geng Nie, Zheng-Liang Gong, Lan Sun, Juan Zuo, Yue-Kun Lai, Chang-Jian Lin

Journal of Electrochemistry

TiO_(2)(B) Nanobelts were synthesized by using the "Soft chemical"method. The products were characterized by means of transmission electron microscope(TEM), X-ray diffraction(XRD), Raman spectrum and energy dispersive spectrum(EDS). Galvanostatic charging and discharging tests showed that lithium-ion intercalation/deintercalation occurred reversibly in the TiO_(2)(B) nanobelts electrode, and a high capacity (265 mAh·g~(-1)) can be obtained. The results suggested that TiO_(2)(B) Nanobelts might be a promising negative electrode material of second Lithium battery.

Preparation Of Photo-Electrochemical Anticorrosion Tio_2 Films By Anodization Method, Peng-Fei Wu, Mou-Cheng Li, Jia-Nian Shen, Mei-Qun Xiao, Dong Liu

Journal of Electrochemistry

Titanium oxide films have photo-electrochemical anticorrosion effect. We investigated the TiO_(2) films prepared by anodization method to protect for 45~(#) carbon steel in man-made seawater(3%NaCl). Various parameters, including voltages, electrolytes nature and concentration of electrolyte were examined. The polarization curves and of TiO_(2) and coupling photo-current curve between TiO_(2) film and 45~(#) carbon steel were measured.

Preliminary Study Of Speek Membranes For Direct Methanol Fuel Cells Application, Su-Zhen Ren

Journal of Electrochemistry

This paper describes the methanol permeability characterization of SPEEK membranes and their feasibility for DMFC application. The SPEEK membranes showed a significant lower methanol permeation than Nafion~115 determined from voltammetric methods. An increase in open circuit voltage was found in the performance of SPEEK membranes in DMFC. The power density of the cell using SPEEK membrane was considerably poorer than that of Nafion~115. If modified properly, the SPEEK membranes can be chosen for DMFC application based on this study.

The Effect Of Ferrous Sulphate On The Electroless Depositionof Co-Fe-P Alloys, Sen-Lin Wang, Qing-Hua Li

Journal of Electrochemistry

Electroless deposition of Co-P alloy and Co-Fe-P alloy from an alkaline bath, containing sodium hypophosphite as a reducer, boric acid as a buffer agent and sodium citrate as a complexing agent, was investigated respectively. The effects of process parameters, such as pH of solution and metallic salt mole ratio of CoSO_(4)/FeSO_(4), on the plating rate were examined. It was found that the presence of ferrous sulfate in the bath has an inhibitory effect on the alloy deposition. As a consequence, the plating rate of Co-Fe-P is lower than that of Co-P. The electrochemical polarization measurements have been carried out to …

Study On An Intermediate Temperature Planar Solid Oxide Fuel Cell, Shao-Rong Wang, Wen-Xia Chen, Ting-Lian Wen, Jia-Di Cao, Zhi-Yi Lv, Da-Qian Wang

Journal of Electrochemistry

Tape cast method was applied to prepare green sheets of Ni/YSZ anode supported YSZ thin film. After isostatic pressure treatment and cosintering, the YSZ film on the Ni/YSZ anode was gas-tight dense, and 15~30 μm thick. The area of the composite film was over 100 cm~(2). A Ce_(0.8)Sm_(0.2)O_(1.9 )(CSO) interlayer was sintered on to the YSZ electrolyte film to protect La_(0.6)Sr_(0.4)CoO_(3 )(LSCO) cathode from reaction with YSZ at high temperatures. The LSCO cathode layer was screen printed onto the CSO interlayer and sintered at 1 200 ℃ for 3h to form a single cell. The obtained single cell was operated …

Fabrication Of Solid Oxide Fuel Cells And Analysis Of Their Structure And Performance, Nai-Tao Yang

Journal of Electrochemistry

An intermediate temperature solid oxide fuel cell (IT-SOFC) was fabricated by co-copressing-sintering methods, and the electrolyte of Ce_(0.8)Gd_(0.2)O_(1.9) (CGO) and cathode materials of La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-α) (LSCF) were prepared by sol-gel method. The effect of preparation methods on the microstructure of the prepared fuel cells was analyzed by SEM . It shows that the cells prepared by the co-pressing/co-sintering method possess a dense electrolyte layer and a compact interface between electrolyte and anode but a curved configuration, while those prepared by the colloidal technique have a flat configuration but the electrolyte layer is not dense enough. The maximum output power density of …