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Articles 25381 - 25410 of 27367

Full-Text Articles in Engineering

Codeposition And Corrosion Resistance Of Nickel-Cerium-Phosphorus Amorphous Alloys, Jiang Liu, Xiong Jiang, Lin-Cai Jiang, Ze-Shan Zhu Aug 2001

Codeposition And Corrosion Resistance Of Nickel-Cerium-Phosphorus Amorphous Alloys, Jiang Liu, Xiong Jiang, Lin-Cai Jiang, Ze-Shan Zhu

Journal of Electrochemistry

The possibility of electrodeposition of rare earth alloys from aqueous bath was investigated using varous techniques such as linear potential sweeping, cyclic voltammetry, electrodepositon at constant potential etc. The Ni-Ce-P alloys with different cerium content were electrodeposited from a weakly acidic solution containing CeCl3, NaH2PO2 and so on the crystal structure and component were characterized by XPS, AES, XRD and SEM observation. The codeposits were found to be more highly corrosion resistent than that of Ni-P amorphous alloys by measuring polarization resistance and corrosion potential. The effects of codeposition conditions on the corrosion resistance were …

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Determination Of Hydrogen Diffusion Coefficient In Metal Hydride Electrode With Electrochemical Impedance Spectroscopy, Xian-Xia Yuan, Nai-Xin Xu Aug 2001

Determination Of Hydrogen Diffusion Coefficient In Metal Hydride Electrode With Electrochemical Impedance Spectroscopy, Xian-Xia Yuan, Nai-Xin Xu

Journal of Electrochemistry

Electrochemical impedance spectroscopy was employed to determine the hydrogen diffusion coefficient in MlNi 3.75Co 0.65 Mn0.4Al0.2 metal hydride electrode with various states of charge (SOC) at room temperature and with 50% SOC at various temperatures. It was found that hydrogen diffusion coefficient in this electrode decreases with the increase in SOC at ambient temperature, and for the electrode with 50% SOC, hydrogen diffusion coefficient increases with the increase of temperature and the activation energy for hydrogen diffusion in it is 35 kJ/mol.

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Electrochemical Impedance Spectroscopy Study On A3 Steel In Anti-Corrosive Pigment Extract Solution, Zhi-Jun Gu, Yong-Gui Liao, Zhi-Gang Zhang, Qi-Long Guo, Fang-Teng Su, Wen-Yun Hu, Yan-Zhen Chen Aug 2001

Electrochemical Impedance Spectroscopy Study On A3 Steel In Anti-Corrosive Pigment Extract Solution, Zhi-Jun Gu, Yong-Gui Liao, Zhi-Gang Zhang, Qi-Long Guo, Fang-Teng Su, Wen-Yun Hu, Yan-Zhen Chen

Journal of Electrochemistry

The corrosion behaviors of A3 steel in different pH, 3.5%NaCl, modified zinc phosphate and aluminum triphosphate extract solutions have been studied by EIS. Results show:(a) The resistance increases with the increase of pH value under the same circumstances, but the capacity is the reverse. (b) Zinc phosphate, because of its low solubility, shows no inhibitive performance for A3 steel in 3.5% NaCl extract solutions. (c) Aluminum triphosphate has good inhibitive performance for A3 steel in 3.5% NaCl extract solutions at a pH of 6, probably because the triphosphate ion can complex with the corrosion-product, such as ferric …

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Bs News Aug 2001

Bs News

Building Services Engineering

No abstract provided.

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43rd Rocky Mountain Conference On Analytical Chemistry Jul 2001

43rd Rocky Mountain Conference On Analytical Chemistry

Rocky Mountain Conference on Magnetic Resonance

Final program, abstracts, and information about the 43rd annual meeting of the Rocky Mountain Conference on Analytical Chemistry, co-sponsored by the Colorado Section of the American Chemical Society and the Rocky Mountain Section of the Society for Applied Spectroscopy. Held in Denver, Colorado, July 29 - August 2, 2001.

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Production Of Biogas From Water Hyacinth: Effect Of Substrate Loading In Semi-Batch & Batch Operations, J Katima Jun 2001

Production Of Biogas From Water Hyacinth: Effect Of Substrate Loading In Semi-Batch & Batch Operations, J Katima

Tanzania Journal of Engineering and Technology (TJET)

A study was carried out to establish the effect of substrate loading rate on the production of biogas from water hyacinth. The experiments revealed that the maximum methane yield in a batch process was 0.166 normal litre (NLVg Of volatile solids (VS) added at substrate concentration of 25 g dry mass'litre after five days of incubation. The maximum methane yield in a semi-batch process was 0.153 NWg VS added at 1.30 g VS'litre day and retention time Of 15 days.

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Efeci's In Reinforced Concrete Due To Environmental Conditions, And Concrete Treatment: A Case Study At The University Of Dar Es Salaam, I Rubaratuka Jun 2001

Efeci's In Reinforced Concrete Due To Environmental Conditions, And Concrete Treatment: A Case Study At The University Of Dar Es Salaam, I Rubaratuka

Tanzania Journal of Engineering and Technology (TJET)

Concrete is produced by mixing together cement, water and aggregates (i. e. sand and coarse aggregates) in specified proportions, It can do well with compressive forces but it is very weak under tensile forces. TO Overcome this problem, steel reinforcement are normally added to produce reinforced concrete which can also withstand tensile forces Experience shows that environmental conditions may have a negative impact On the durability of reinforced concrete structures resulting in development of defects if not properly assessed and appropriate measures adopted to arrest the same at the design and construction stages. The severity of damages for the investigated …

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Some Aspects Of Erosive Waves At Kunduchi Beach, Dar Es Salaam, Tanzania, Alfonse Dubi Jun 2001

Some Aspects Of Erosive Waves At Kunduchi Beach, Dar Es Salaam, Tanzania, Alfonse Dubi

Tanzania Journal of Engineering and Technology (TJET)

The area north of the Dar es Salaam City is endowed with beautiful sandy beaches and high concentration or tourist beach hotels that are threatened by coastal erosion. In order to protect the buildings and land, coastal erosion must be controlled by mitigation options that are based on scientific data, wave and current climate along the East African region are generally controlled by the seasonal monsoon winds. During the north-east monsoon period when Winds blow from the Northeast, the wind-generated waves approach the coast from the northerly direction and produce long-shore Currents With a southerly component. During the southerly monsoon …

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Stress Conditions In The Kilombero Rift, Central Tanzania, A Mruma Jun 2001

Stress Conditions In The Kilombero Rift, Central Tanzania, A Mruma

Tanzania Journal of Engineering and Technology (TJET)

The ancient and current Stress conditions at the northwestern flank of the Kilombero Rift are assessed in this paper. Neoproterozoic Stresses in the area were associated With 3200/200 trending principal axis of straining in the rocks. Ihis deformation imparted Precambrian ductile gneissic and concordant mineral foliation with attitude Of 0200/3$WNW, 3200/200 trending b•minerai lineation and isoclinal folds With axes trending parallel to the mineral lineation.phanerozoie deformations are mainly of pennvrriasic and Cenozoic periods. Both Of the two episodes Of deformation had constant orientation of princi axes of stresses with trending 0600/020, 02 trending 1600/800 and trending 33 1100. Stress conditions …

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Electrokinetic Cha Raci'erisation Of Colloidal A-Alumina, J Ntalikwa Jun 2001

Electrokinetic Cha Raci'erisation Of Colloidal A-Alumina, J Ntalikwa

Tanzania Journal of Engineering and Technology (TJET)

Electrophoretic mobility (uD is an important rneasurable parameter in studying the electrokinetic properties of a colloid dispersion. This parameter is Often convened into zeta potential (C) Which piays a great role in thc description Of the stability towards aggregation Of dispersed particles. In this paper, measurements of Of colloidal a-alumina dispersed in various concentrations of electrolyte arc reported. It was observed that, the isoelectric points (the pH at which us = O) occurred at 7.52 ± 0.32, 8.05 ± 0.11 and 7,95 ± 0.18 in Naci, KCI and NaNOs respectively. The isoelectric point was observed to be a function Of …

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Comparative Analysis Of Rng K-E And 'Standard' K-C Models For Fluid Flow Around A Cylinder, A Temu Jun 2001

Comparative Analysis Of Rng K-E And 'Standard' K-C Models For Fluid Flow Around A Cylinder, A Temu

Tanzania Journal of Engineering and Technology (TJET)

A two-dimensional computational scheme for simulating fluid flow around a cylinder was investigated. RNG (Re-NOrmalisation Group) and 'standard' turbulent closure models were used. simulation was implemented with assistance OfFLOW-3D computational fluid dynamics (CFD) code. The governing equation Of fluid motion, in Eulerian form, included body forces as well as surface forces. The computational model predictions for fluid velocity showed good agreement between the two models. Comparison Of the viscosities showed a large deviation from the two models, with RNG k-E model giving a better approximation. Comparison Of the velocity around the cylinder, as obtained from RNG k-c model, with approximation …

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Recyclability Of Modified Ps-Aq Pulps At Around Kappa 30, Rwaichi Minja Jun 2001

Recyclability Of Modified Ps-Aq Pulps At Around Kappa 30, Rwaichi Minja

Tanzania Journal of Engineering and Technology (TJET)

Bleachable grade pulps prepared from Nonvegian softwood spruce chips while simulating possible alternatives of improving pulp yield by application Of polysulphide (PS) and anthraquinone (AQ) have been used in this study. The tests for recyclability were performed on hydrogen form pulps. The pulps considered were Iso- Thermal cooking (ITC) kraft pulp which was used as a reference pulp, conventional PS-AQ pulp, soda PS-AQ pulp and kraft PS-AQ pulp. The loss Of swelling ability (homification) Of the pulps, was determined by measurement of water retention value (W R V). The results showed that, PS-AQ pulps had similar or slightly better swelling …

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Baseflow Separation Based On Storage-Outflow Modelling Of Streamflow Recessions, With Application To Semi- Arid Catchments In Tanzania, S Mwakalila Jun 2001

Baseflow Separation Based On Storage-Outflow Modelling Of Streamflow Recessions, With Application To Semi- Arid Catchments In Tanzania, S Mwakalila

Tanzania Journal of Engineering and Technology (TJET)

Discharge in many rivers is Often fed by baseflow provided by drainage of the saturated zone in the shallow permeable soils. It is becoming clear that the outflow from this saturated zone is not linear proportional to storage as is commonly assumed in many algorithms. The objectives Of this study theretore, are first to explore the extent to which the assumption of linearity in storage-outflow relationships is valid and secondly to introduce an alternative approach to baseflow separation algorithms for estimating direct mnoff time series. Numerical analysis Of streamflow recessions from the semi-arid catchments of the Great Ruaha basin in …

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A Study Into Lack Of Product Innovation And Business Techniques At The Tricycle Workshop And Rrs Lessons To Small Companies, E Elias Jun 2001

A Study Into Lack Of Product Innovation And Business Techniques At The Tricycle Workshop And Rrs Lessons To Small Companies, E Elias

Tanzania Journal of Engineering and Technology (TJET)

A study was carried out at the Tricycle Workshop (TW) which was facing the problem of !ack of orders and therefore stagnation Of business. The objective of the study was to find out reasons for this situation and to propose possible remedial solutions. The study was conducted using the principles of the Product Innovation process where internal and external issues related to the business Of the company were investigated for information. Analysis Of information obtained indicated that the bad situation of the TW had mainly been caused by the nature of the tricycles-supply system whereby users (disabled persons) are unable …

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Roll Motion Of A Roro-Ship In Irregular Following Waves, Jianbo Hua, Wei-Hui Wang Jun 2001

Roll Motion Of A Roro-Ship In Irregular Following Waves, Jianbo Hua, Wei-Hui Wang

Journal of Marine Science and Technology–Taiwan

A RoRo-ship usually has a fine hull form with large flare at bow and stern. In order to achieve large cargo space, large ratio of the beam to draught are quite common for this kind ship. Such a hull configuration can be subjected to considerable variation of the metacentre height as she sailing in waves. As a consequence the parametric excitation becomes considerably great so that a large roll motion appears. This is a strongly nonlinear problem. A simplified model is formulated in this paper to take account for the parametrically excited roll motion of a RoRo-ship in irregular following …

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Dual Boundary Integral Equations For Helmholtz Equation At A Corner Using Contour Approach Around Singularity, I-Lin Chen, Ming-Te Liang, Shyh-Rong Kuo, Jeng-Tzong Chen Jun 2001

Dual Boundary Integral Equations For Helmholtz Equation At A Corner Using Contour Approach Around Singularity, I-Lin Chen, Ming-Te Liang, Shyh-Rong Kuo, Jeng-Tzong Chen

Journal of Marine Science and Technology–Taiwan

A dual integral formulation for the Helmholtz equation problem at a corner is derived by means of the contour approach around the singularity. It is discovered that employing the contour approach the jump term comes half and half from the free terms in the L and M kernel integrations, respectively, which differs from the limiting process from an interior point to a boundary point where the jump term is descended from the L kernel only. Thus, the definition of the Hadamard principal value for hypersingular integration at the collocation point of a corner is extended to a generalized sense for …

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The G-Based Jordan Algebra And Lie Algebra With Application To The Model Of Visco-Elastoplasticity, Chein-Shan Liu Jun 2001

The G-Based Jordan Algebra And Lie Algebra With Application To The Model Of Visco-Elastoplasticity, Chein-Shan Liu

Journal of Marine Science and Technology–Taiwan

By a matrix representation the g-based Jordan algebra [1] is proved to form a g-based Lie algebra under the commutator product. Then we derive a new dynamical system based on the composition of the g-based Jordan and Lie algebras, which possesses internal symmetry group DSOo(n,1), and its projection PDSOo(n,1). Utilizing this concept we obtain a linear representation of a constitutive model of visco-elastoplasticity with large deformation. The irreducible representation in the vector space admits of the projective dilation proper orthochronous Lorentz group PDSOo(5,1) in the visco-elastoplastic phase and the dilation special Euclidean group DSE(5) in the viscoelastic phase. The input …

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Resonance Of Continuous Bridges Due To High Speed Trains, Jong-Dar Yau Jun 2001

Resonance Of Continuous Bridges Due To High Speed Trains, Jong-Dar Yau

Journal of Marine Science and Technology–Taiwan

In this paper, the vibration of continuous bridges subjected to the passage of high-speed trains is studied. Only the bridges with uniform spans are considered and the train moving over a bridge is modeled as a series of moving loads. According to the resonant formula of simple beams to moving loads, the effect of multiple resonant peaks for continuous bridges subjected to high-speed trains can be determined by analogy method. Based on the finite element method, the effect of the number of spans on the impact response of the continuous beams is presented. The results show that the more the …

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Design And Preliminary Test On The Integration Of Weather Data In Ecdis For Marine Navigation, Shwu-Jing Chang Jun 2001

Design And Preliminary Test On The Integration Of Weather Data In Ecdis For Marine Navigation, Shwu-Jing Chang

Journal of Marine Science and Technology–Taiwan

The incorporation of marine weather information into Electronic Chart Display and Information System (ECDIS) has become a major issue common to international organizations such as IMO, IHO, and WMO. It is believed that this will further enhance the effectiveness of ECDIS as a tool of decision support to mariners for safe and efficient navigation. This paper first identifies essential items of marine weather information to be integrated into ECDIS. The data structure, formats, and symbology for the display and updating of weather data in ECDIS are then proposed according to related international standards. Potential use of weather data in ECDIS …

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The Design Of Fuzzy Collision-Avoidance Expert System Implemented By H∞ - Autopilot, Cheng-Neng Hwang, Joe-Ming Yang, Chung-Yen Chiang Jun 2001

The Design Of Fuzzy Collision-Avoidance Expert System Implemented By H∞ - Autopilot, Cheng-Neng Hwang, Joe-Ming Yang, Chung-Yen Chiang

Journal of Marine Science and Technology–Taiwan

Collision avoidance is one of the urgent topics on ship voyage at sea. Experts’ experience is still essential when a ship is in the danger of colliding with the others nowadays although a lot of electronic voyage supported apparatuses have been equipped on ships. To include these experts’ experiences to resolve the problems of collision, we design a fuzzy collision-avoidance expert system that includes a knowledge base to store facts and rules, an inference engine to simulate experts’ decision and a fuzzy interface device. Either a quartermaster or an autopilot system can then implement the avoidance action proposed in the …

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Predicting The Integrity Of Existing Prestressed Concrete Bridge Deck Using Sonic Method, Ming-Te Liang, Jyi Wu Jun 2001

Predicting The Integrity Of Existing Prestressed Concrete Bridge Deck Using Sonic Method, Ming-Te Liang, Jyi Wu

Journal of Marine Science and Technology–Taiwan

The principal objective of this paper was provided a general idea for predicting the integrity of existing prestressed concrete bridge decks by using sonic method. The governing equation is a onedimensional wave equation with initial conditions. The method of Fourier transform was adopted for seeking D'Alembert's solution which is an analytical solution of the governing equation. Furthermore, the wave formulae such as displacement, velocity, force and stress waves were derived from the analytical solution. If the viscosity effect of material was neglected, then the elastic wave can be reduced as the sonic wave. Through these sonic wave formulae, the damage …

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Analysing Construction Risk : A Project Management Model, P K Dey Jun 2001

Analysing Construction Risk : A Project Management Model, P K Dey

IIMB Management Review

The success parameters for any project are ontime completion within the specific budget, and requisite performance or meeting the technical requirements. The main barriers to achievement are changes in the project environment. The problem multiplies with the size of the project. Large-scale construction projects are exposed to an uncertain environment because they are subject to such factors as planning and design complexity, presence of various interest groups (project owner, owner’s project group, consultants, contractors, vendors etc), availability of resources (materials, equipment, funds etc), climatic environment, the economic and political environment and statutory regulations. Other risk factors include the complexity of …

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Bs News Jun 2001

Bs News

Building Services Engineering

No abstract provided.

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Performance Of Proton Exchange Membranefuel Cell With Co/H2 Fuel, Hong-Mei Yu, Zhong-Jun Hou, Bao-Lian Yi, Ke-Wan Bi, Jing-Xin Zhang, Zhi-Yin Lin, Ming Han May 2001

Performance Of Proton Exchange Membranefuel Cell With Co/H2 Fuel, Hong-Mei Yu, Zhong-Jun Hou, Bao-Lian Yi, Ke-Wan Bi, Jing-Xin Zhang, Zhi-Yin Lin, Ming Han

Journal of Electrochemistry

Fuel of proton exchange membrane fuel cell(PEMFC) mostly comes from reformatecontains CO which will poison the fuel cell electrocatalyst. The effect of CO on the performance of PEMFC was studied in this paper. The results of the experiment show that when CO is fed inPEMFC ,the cell voltage will be decreased violently,then it will become steady with some vibration. The poison will become more serious with higher CO content and weaker at higher temperature. The adsorption of CO on the electrocatalyst is reversible. The PtRu electrocatalyst is moresuitable for the electrocatalysis of CO/H2 than Pt electrocatalyst.

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Atmospheric Corrosion Of Steels In China, Cai-Feng Liang May 2001

Atmospheric Corrosion Of Steels In China, Cai-Feng Liang

Journal of Electrochemistry

Data of eight year atmospheric exposures of 17 steels at 7 sites in China were analyzed. The result showed that the most detrimental pollution is sulfur dioxide and chloride ion for corrosion of carbon steels and low alloy weathering steels. This is in accordance with the common knowledge.The effect of sulfur dioxide is serious in the first few years and becomes weak obviously in the later years. The environment factor of humid hot is much more important in long run than the ordinarily acknowledged humidity, pollution for non weathering steels,although it is not obvious in the beginning. If pollution were …

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Properties Of Metallized Polyo-Toluididemembrane Modified Electrode, Li-Zong Dai, Yi-Ting Xu, Hui-Huang Wu May 2001

Properties Of Metallized Polyo-Toluididemembrane Modified Electrode, Li-Zong Dai, Yi-Ting Xu, Hui-Huang Wu

Journal of Electrochemistry

The platinum particles were electrodeposited on poly(o-toluidide), POT, modified electrode, and the surface configuration and crystal orientation of Pt particles were investigated by SEM and XRD. At the same time the oxidation of isopropanol on platinized POT modified electrode was studied. The results indicate that Pt particles deposite towards preferred-orientation; moreover the increase in polymer electroactivity due to proton doping affects the dimension and graininess of deposited Pt particles. At the metallized polymer electrode the oxidation of isopropanol can occur in POT electroactive potential region, however at the more positive than 0.70 V (SCE) potential where POT loses redox activity …

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Galvanic Corrosion Of Tin-W Electro-Couple During Tungsten Chemical Mechanical Polishing, Xuan Cheng, Chang-Jian Lin May 2001

Galvanic Corrosion Of Tin-W Electro-Couple During Tungsten Chemical Mechanical Polishing, Xuan Cheng, Chang-Jian Lin

Journal of Electrochemistry

Chemical mechanical polishing (CMP) is a process whereby mechanicaland chemical forces are combined to remove material from a wafer and polish it to a flatsurface. Tungsten CMP is an important prcess to gain the global planarity of siliconwafers with tungsten (W) plugs. Tungsten is actually deposited on a thin adhesive layerof titanium nitride (TiN) on silicon. When close to the final stage of polishing, TiN and W will be simultaneously exposed to the polishing chemistry, forming a galvaniccouple. The corrsion of TiN and W couple will result in different polish rate.

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Electrochemical Behavior Of Tinicu Shape Memry Alloy In Simulated Body Fluid, Cheng-Hao Liang, Hong-Yan Sui May 2001

Electrochemical Behavior Of Tinicu Shape Memry Alloy In Simulated Body Fluid, Cheng-Hao Liang, Hong-Yan Sui

Journal of Electrochemistry

The study of TiNiCu shape memory alloys (SMA) in Hank's simulated body fluidwas carried out. The results showed that narrow passive range was found in acid environment andactive anodic dissolution was discovered at 100~150 mV vs SCE on anodic polarization cure ofTiNiCu SMA. Temperature had little effect on anodic polarization. With the decrease of pH andthe increase of Cl- concentration ,pitting corrosion potential (Eb) shifted negatively. The electrochemical capability of TiNiCu SMA was inferior to that of TiNi SMA. Observations by means ofXRD and SEM indicate that TiNiCu SMA is not in single crystal structure, which caused …

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Study Of The Oxidation Dynamics Of Tizro2 Metal-Ceramics, Wen-Chao Li, Li-Dong Teng May 2001

Study Of The Oxidation Dynamics Of Tizro2 Metal-Ceramics, Wen-Chao Li, Li-Dong Teng

Journal of Electrochemistry

The oxidation dynamics of hot-pressed Ti-ZrO2 metal-ceramics with the compositionof 50 vol.% Ti and 50 vol.% ZrO2 has been studied.Thermodynamic analysis shows that Ticould react with O2 but not with N2 in the oxidizing process of TiZrO2 composites at 0.1 MPa air. The oxidation dynamic behavior of Ti-ZrO2 composites is analogous to that of pure Ti. Theactivation energy for the oxygen diffusion in Ti-ZrO2 composites is higher than that in Ti solutions, for the presence of ZrO2 restrains the oxygen diffusion in Ti-ZrO2 composites. At early stagethe oxidation of Ti-ZrO2 …

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Preparation And Properties Of Separator For Lithium-Ion Battery, Xu-Mei Ren, Feng Wu, Chuan Wu, Han-Jun Li, Xue-Jie Huang May 2001

Preparation And Properties Of Separator For Lithium-Ion Battery, Xu-Mei Ren, Feng Wu, Chuan Wu, Han-Jun Li, Xue-Jie Huang

Journal of Electrochemistry

Lithium-ion batteries are well adapted to the new multimedia applications. PP/PE based microporous film is commonly used as separator in commercial lithium ion batteries. Herewe report a microporous film which is superior to the commercial available separator. The microporous PVDF polymer separators were prepared by the phase inversion process. The pore size of the separator is Φ 7 μm , and it's porosity is 75 %. The membrane in LiPF6-EC/DEC showedhigh ionic conductivity (above 10-3 S/cm at room temperature), and good mechanical properties(103 kg/cm2). The half-cells consisted of Li/PVDF separator/MCMB showed excellent cyclingcharacteristics and …

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