bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence Research on Pit Excavation Close to Existing Shield Tunnel
Authors: Liu Lin , Ge Peng Fei , Wei Gang , Ying Zhi Jie , Luo Can Fang , Fei Xia Ting
Published: March 2013

Pit excavation has a negative impact on the existing shield tunnel close to it. The deformation mechanism of the existing tunnel during the pit excavation was analyzed. Theoretical analysis results shows: excavation unloading decreases the pressure in horizontal direction of the tunnel, which causes tunnel taking the horizontal displacement to the pit side; convergent deformation keeps in horizontal stretching, vertical compression, but the deformation is aggravated; tunnel vertical uplift or settlement is determined by the pit excavation depth; precipitation would make tunnel sinking. Five domestic pit excavation engineering instance was collected, and the reliability of the analysis in this article is proved by the statistical analysis of the measured data.
Analysis of Cracking Moment and Immediate Deflection in FRP Rebars Reinforced Concrete Beams
Authors: Liu Shun Feng , Hou Mu Yi , Liu Xiao , Wang Ru Heng
Published: March 2013

Fiber reinforced polymer rebars have advantages of light weight, high tensile strength and excellent corrosion resistance. However, researches showed that [1-2], the low elastic modulus of FRP rebar resulting in a larger deflection than steel reinforced concrete beam in equivalent condition. Therefore, it is crucial to control the deflections in serviceability limit states. Three GFRP reinforced concrete beams were tested with four-point bending, deducing the cracking moment formula of the FRP reinforced beam. Then, Bischoff model is adopted to calculate the deflection, and reaching a good agreement with the experimental results. We recommend Bischoff model to evaluate the immediate deflections.
Introduction of Regional Confined Concrete
Authors: Cao Xin Ming , Huang Xian Wu , Mo Zhi Gang , Tian Hong Yuan
Published: March 2013

Based on the research of normal confined concrete (NCC), regional confined concrete (RCC) was proposed years ago by authors. With the introduction of regional confinement concept, different mechanical properties, failure mode and energy dispatching property developed in the regional confined concrete elements. Experimental researches have been carried out during the past years on the elements under various loads, including beams under moments, short beams under shears, short columns under axial loads, middle long columns under eccentric loads, middle long columns under axial loads and columns under cycling loads. Experimental results indicated that RCC elements are more ductile, have better load carrying capacity and larger energy dispatch capacity than that of NCC elements. Stress-strain relationship of RCC, integrated confinement factor and some computation expressions for elements under various loads are proposed. Pilot projects have been conducted and regional confined concrete structures are ready for service.
The Experimental Research on the Reinforced Concrete Beam Performance of Crack Repair
Authors: Zhang Fang , Hao Jin Feng , Liu Gui De , Gao Jin Feng
Published: March 2013

The reinforced concrete simple-supported beams are made, applied load continuously until there product crack in them. Then, we select the binder to repair the crack and load them secondly. We verify the performance of the binder by experiment.
Large Span Continuous Girder Bridge Jacking Steel Hoop Stress Analysis
Authors: Chen Zhou , Yan Quan Sheng , Jia Bu Yu , Yu Xiao Lin
Published: March 2013

Bridge jacking technology is a new technology in the field of old bridge reconstruction. Based on the case of Beijiang River Bridge jacking of Fokai highway extension engineering, the paper designs steel hoop as jacking force platform. By using ANSYS software, it makes finite element analysis and calculation as well as compares with the experimental data to check the reliability of models. In addition, the paper puts forward the optimization methods of steel hoop based on the analysis of the results. At last, it achieves the objective of saving materials and simplifying installation and use as well as provides guidance for the similar engineering.
Effect of Austenitising Temperature on Microstructural Changes in High-Speed Steel of M2 Type Inoculated with Addition of WC Powder
Authors: Chaus Alexander S. , Beznák Matej , Porubský Ján , Sojka J.
Published: March 2013

The transformation of the solidification microstructure in AISI M2 grade high-speed steel inoculated with powder addition of WC have been studied focusing on the effect of austenitisation. In order to investigate the kinetics of both the microstructure and phase transformations in eutectic carbides, primarily M2C carbide decomposition, upon heat treatments with respect to diffusion processes, electron scanning microscopy, XRD analysis and EDS have been used.
Thermochemical Nitriding of Commercial Purity Titanium
Authors: Ipekci Meltem , Seahjani Fared , Çimenoğlu H.
Published: March 2013

Commercial purity titanium samples were gas nitrided for 3, 5, 7 and 12 h at 1250°C. TiN layers with nitrogen diffusion zones were formed on the surfaces, which caused an increase in the surface hardness with respect to the processing time. In addition, nitriding provided a reduction in friction coefficient and an enhancement in wear resistance against an alumina ball under dry sliding conditions.
Evaluation of the Impact of Temperature and Type of Catalyst on the Bio-Oil Quality Obtained by Biomass Catalytic Pyrolysis Process
Authors: Mendes F.L. , Pinho A.R. , Figueiredo M.A.G.
Published: March 2013

The pyrolysis of biomass is a thermal process that converts, at high yield, solid biomass into a liquid product known as bio-oil. One alternative for the production of a bio-oil of better quality and with lower oxygen content is the use of catalysts in the pyrolysis reactor, rather than an inert, a process called catalytic pyrolysis. The objective of this study was to investigate the effects on product yields and the qualities of products of two different catalysts, one acidic, a commercial fluid catalytic cracking (FCC) catalyst, and a basic one containing hydrotalcite. Inert material, a type of silica, was used as reference. The tests were conducted in a pilot plant with a circulating fluidized bed reactor, specially adapted to perform the catalytic pyrolysis tests, at temperatures of 450°C and 550°C. The results showed that the increase in the residence time of the pyrolysis vapors had a significant impact on products yields, when compared with the profile found in the literature for fast pyrolysis. The FCC catalyst presented higher deoxygenation rates by dehydration, while the hydrotalcite showed greater capacity for decarboxylation. Thus, the use of either the FCC catalyst or hydrotalcite are not suitable for intermediate pyrolysis reactors, generating a product with high water content and low content of organic compounds in bio-oil and produce more coke. None of the materials tested produced bio-oils with considerable hydrocarbons yields and presented high amounts of phenolic compounds. In general, silica had the best results in terms of yield and quality of bio-oil.
Analysis of Impact of Selected Structure Parameters of Reinforcing Preforms for Metal-Matrix Composites on their Saturation Process
Authors: Nagolska Dorota , Gawdzińska Katarzyna
Published: March 2013

The process of saturation of reinforcement preforms for metal-matrix composite castings is dependent on many different factors. One group of these factors is related to the process of manufacturing of metal-matrix composites with saturated reinforcement. Another group is related to the physical properties of materials used for manufacturing of such composites. The structure of reinforcement preforms is one of such factors. Due to its complexity, its mathematical description is difficult to perform. This structure can be examined and described using physical properties like porosity or permeability. During the conducted analysis presented in the paper, it was checked whether there is a relation between studied physical properties of reinforcement preforms and a degree of their saturation. It was also determined, which of the studied parameters is the best for description of an influence of the geometrical structure of reinforcement preforms on the process of their saturation and in consequence, on the porosity of the obtained composite castings.
2D Flow in a Wall-Bounded Porous Medium
Authors: Ferreira de Sousa P.J.S.A. , Malico Isabel , Fernandes Gérson
Published: March 2013

A compact finite differences method is used to calculate two-dimensional viscous flows through complex geometries. The immersed boundaries are set through body forces that allow for the imposition of boundary conditions that coincide with the computational grid. Two different flow configurations are simulated. First, the flow through a row of cylinders with square cross-sections is calculated and used as a validation study. The computed average drag coefficient and Strouhal number are compared to data available in the literature, showing a good agreement between the results. The second flow configuration analyzed is the flow through a porous matrix composed of equal size staggered square cylinders. Flow visualization results are shown and various flow regimes identified. Different inlet boundary conditions are compared. The drag coefficient is larger when a uniform inlet velocity is prescribed and the variability between cylinders is lower.
Effect of Mechanical Activation on the Electrochemical Behavior of MnO2
Authors: Kozhina G.A. , Ermakov A.N. , Fetisov V.B. , Fetisov A.V. , Shunyaev K. Y. , Dmitriev Andrey N. , Petrova S.A. , Zakharov Robert Grigorievich
Published: March 2013

Electrochemical behaviour of mechanoactivated β-MnO2 powders has been studied by the method of cyclic voltammetry with a carbon-paste electroactive electrode. Mechanical activation was carried out by dry grinding in an AGO-2 planetary ball mill. It was found that the grinding process results in a mechanochemical effect in the surface layer of the oxide particles: Mn (IV) cations are reduced to Mn (III). Voltammetry test detects that mechanical activation of β-MnO2 leads to a new state, which is characteristic for the γ-modification of manganese dioxide (β-MnO2 γ-MnO2).
Optical Chemical Nanosensors in Clinical Applications
Authors: Turel Matejka , Mastnak Tinkara , Lobnik Aleksandra
Published: March 2013

Because of their size and versatile chemistry, nanomaterials represent today powerful tools for (bio) sensing applications. Various types of nanomaterials have proven to be practical, not only for the determination of clinically relevant parameters, but also for diagnostics, drug delivery and treatment of diseases (e.g. cancer). In this short review, types of nanomaterials used in medical applications are briefly described along with some of their applications where the nanomaterials optical properties can be exploited. The question of the toxicity of nanomaterials and the issue of future trends are also raised.
A New Approach to Surface Tension According to the Surface Topographical Features in Laser Cutting Technology
Authors: Harničárová Marta , Valíček Jan , Müllerová Jana , Kušnerová Milena , Grznárik Radovan , Koštial Pavel
Published: March 2013

Laser - cut quality is mainly characterized by a degree of accuracy in shape, size and also by surface layer conditions after cutting associated with surface roughness. An experimental determination of surface tension (or tensor components) of clean metal surfaces is very difficult and there is no direct method for its measurement. Attention was paid to numerical derivation of surface tensions according to the surface topographical features in laser cutting technology. The surface tensions and temperature dependencies of several metallic materials have been determined and confirmed by data obtained from the literature. It was found to be in very good agreement between our results and data from different sources in the literature.
Assessment of Energy Consumption and Internal Stresses in Surface Layer in the Abrasive Electro-Discharge Grinding (AEDG) Process
Authors: Golabczak Andrzej , Swiecik Robert
Published: March 2013

In this work, results have been presented related to the influence of selected electrical parameters of the AEDG process on the energy consumption and state of the internal stresses in the outer layer at this stage of the process, in comparison with conventional grinding. The basis of this work has been possible by investigations of the deep grinding of surfaces of the titanium alloy Ti6Al4V with the use of a CBN grinding wheel and sintered carbide S20S with using diamond grinding wheel with metallic binding agent. For the comparative evaluation of the conventional grinding and AEDG, measurements of the specific grinding energy, energy of the spark discharge and internal stresses in the surface layer have been used.
Defect Detection in Optical Disk Substrate by Mach-Zehnder Interferometer
Authors: Takahashi Yoshitaka , Morishima Kazuki , Yokota Masayuki
Published: March 2013

In recent years optical disks have been very popular and in manufacturing process error detection in optical disks becomes very important, especially for the defects whose size of a few millimeters in length and several hundred nanometers in depth. The authors have developed a new system to measure the defects of disk substrates using a Mach-Zehnder interferometer with a phase shifting method. But it was found that optical disks had undulation of the optical thickness and it disturbed the detection of defects. To solve the problem moving-average method was developed and introduced in data processing to distinguish the defect from the undulation, and with modified unwrapping program the defect was visualized by binary image processing.
Multiple-Valued Pulse-Position Modulation Techniques for Efficient Data Transmission
Authors: Yuminaka Yasushi , Okui Masaaki
Published: March 2013

This paper proposes multiple-valued pulse-position modulation (MVPPM) techniques toachieve efficient data transmission in VLSI systems. The MVPPM coding employs 2-dimensional informationrepresentation in both time and amplitude domain to increase data rates. This time-domaininformation processing uses timing resolution, and therefore fits well with advanced high-speed lowvoltageCMOS processes. An 8-valued MVPPM transceiver is designed and simulated using SPICE todemonstrate the capability of compensating for deterioration of signals caused by interconnections.
Development of Particle Packed Bed Type Chromatography Using Dielectrophoresis
Authors: Umezawa Yusuke , Kobayashi Okihisa , Kanai Syoji , Hakoda Masaru
Published: March 2013

In this study, we analyzed differences in cell species using dielectrophoresis (DEP) and propose a particle packed bed type chromatography device using DEP. Mouse-hybridoma 3-2H3 cells were used as the sample cells. The 3-2H3 cell suspension was fed pulse-wise to a carrier flow and the sample was measured by an absorption spectrometer. The analytical characteristic of chromatography using DEP was evaluated by the retention time difference. We examined the effects of the diameter of packed particles on the retention time difference. The retention time difference in the case of the packed particles of 100 μm diameter was larger than that of 500 μm, which suggests that packed particles of smaller diameter are suitable for analysis using DEP chromatography.
Some Remarks on the Numerical Modelling of Localized Failure
Authors: Bruhns Otto T.
Published: March 2013

An efficient numerical framework suitable for three-dimensional analyses of brittle material failure is presented. The proposed model is based on an (embedded) Strong Discontinuity Approach (SDA). Hence, the deformation mapping is elementwise additively decomposed into a conforming, continuous part and an enhanced part associated with the kinematics induced by material failure. To overcome locking effects and to provide a continuous crack path approximation, the approach is extended and combined with advantages known from classical interface elements. More precisely, several discontinuities each of them being parallel to a facet of the respective finite element are considered. By doing so, crack path continuity is automatically fulfilled and no tracking algorithm is necessary. However, though this idea is similar to that of interface elements, the novel SDA is strictly local (finite element level) and thus, it does not require any modification of the global data structure, e.g., no duplication of nodes. An additional positive feature of the advocated finite element formulation is that it leads to a symmetric tangent matrix. It is shown that several simultaneously active discontinuities in each finite element are required to capture highly localized material failure. The performance and predictive ability of the model are demonstrated by means of two benchmark examples.
A Study on Accelerated Life Test of Spring Unit for Semi-Auto Sliding Mechanism of IT Devices
Authors: Jeon Yong Phil , Seo Hyung Yoon , Kim Jong Deok , Kang Chung Gil
Published: March 2013

Recently, the demand for energy is growing at a very high rate all over the world. The fossil fuels eventually lead to the foreseeable depletion of limited fossil energy resources. Hydrogen is considered a promising candidate to remedy the depletion of fossil fuels. The bipolar plate is the second most important component of a proton exchange membrance (PEM) fuel cell stack after the membrance electrode assembly (MEA). Its primary roles are to supply reactant gases to the fuel cell electrodes and provide electrical connection between adjacent cells in the stack while removing product water from the cell and transferring away the heat of reaction. Historically, machined graphite had been chosen as a good compromise between all of these requirements, but alternatives are emerging. New materials are light metals. In this study, rubber pad forming process was employed as the manufacturing method for metallic bipolar plates. The rubber pad and the sheet metal plate were pressed together by the punch, and the repulsive force of the deformed rubber is loaded at the plate, and can contribute to improving formability. And then, its surface was coated with TiN. After coating process, the performance characteristics of single stack in the condition of PEMFC using the metal bipolar plate have been investigated.
Metallic Bipolar Plate Fabrication Process of Fuel Cell by Rubber Pad Forming and its Performance Evaluation
Authors: Jung Min Geun , Jeon Yong Phil , Kang Chung Gil
Published: March 2013

Recently, the demand for energy is growing at a very high rate all over the world. The fossil fuels eventually lead to the foreseeable depletion of limited fossil energy resources. Hydrogen is considered a promising candidate to remedy the depletion of fossil fuels. The bipolar plate is the second most important component of a proton exchange membrance (PEM) fuel cell stack after the membrance electrode assembly (MEA). Its primary roles are to supply reactant gases to the fuel cell electrodes and provide electrical connection between adjacent cells in the stack while removing product water from the cell and transferring away the heat of reaction. Historically, machined graphite had been chosen as a good compromise between all of these requirements, but alternatives are emerging. New materials are light metals. In this study, rubber pad forming process was employed as the manufacturing method for metallic bipolar plates. The rubber pad and the sheet metal plate were pressed together by the punch, and the repulsive force of the deformed rubber is loaded at the plate, and can contribute to improving formability. And then, its surface was coated with TiN. After coating process, the performance characteristics of single stack in the condition of PEMFC using the metal bipolar plate have been investigated.
Effects of Cell-Wall Angle on the Mechanical Properties of Hexagonal Honeycombs
Authors: Hu Ling Ling , Yu Tong Xi
Published: March 2013

The y-directional mechanical properties of hexagonal honeycombs with various cell-wall angles are explored. The results of both the quasi-static experiments and the dynamic simulations show that the cell-wall angle has a significant influence on the honeycombs’ mechanical properties, although the latter is dominated by the honeycombs’ relative density. This influence is weakened by the increase of the impact velocity. With retaining the honeycombs’ relative density as constant, the honeycomb with the cell-wall angle of about 45o exhibits the optimal crushing strength and energy absorption capacity.
Mechanical Response of Composite Sandwich Panels: Deformation and Energy Absorption
Authors: Vcelka Martin , Durandet Yvonne , Berndt Christopher C. , Ruan Dong
Published: March 2013

The collapse modes and energy absorption in three-point bending of composite sandwich beams were explored experimentally. Sandwich beams manufactured from woven carbon fibre face sheets encapsulating aluminium foam cores were investigated at 0.001 s-1 and 100 s-1 strain rates. Three modes of failure were observed during deformation: Modes H1, H2 and H3. The direction of core shear played an important role in the energy absorption of the structure. Mode H2 gave rise to the highest specific energy absorption of the composite sandwich beams studied.
Plastic-Bending of Adhesively Bonded Dissimilar Sheet Metals
Authors: Takiguchi Michihiro , Tokuda Taro , Yoshida Tetsuya , Funaki Mitsuo , Hamasaki Hiroshi , Yoshida Fusahito
Published: March 2013

In this paper, the effect of material characteristics on plastic forming of adhesively bonded dissimilar sheet metals was investigated by experiments and finite element method (FEM). The acrylic adhesive employed in the experiments has visco-plasticity characteristics with high ductility and strong strain-rate and temperature sensitivity in strength. Major results obtained are summarized as follows: (1) In the adhesively bonded dissimilar sheet metals, the gull-wing bend and the shear deformation of the adhesive layer are suppressed by the combination of the sheet metals when a bending inside sheet has high-tensile strength. (2) The gull-wing bend is suppressed by high-speed forming at a lower temperature as well as the same kind of sheet metals. (3) The calculated results using MSC Marc2010 are relatively good agreement with the experimental results.
Dynamic Response of Aluminum Foam Sandwich Panel to Transverse Impact
Authors: Wang Zhi Hua , Li Xin , Li Zhi Qiang , Zhao Long Mao
Published: March 2013

The dynamic response of aluminum foam sandwich panels are studied experimentally by impacting the panels at mid-span with metal foam projectiles. Two types of core are considered: open-cell foam and closed-cell foam. By changing the launching speed of metal foam projectiles, different deformation/failure modes of sandwich panels are obtained. Strain history of face sheets in different positions is also recorded by strain gauges to observe its deformation mechanism. The experiment results indicated that when the strength of core is relatively small and the impulse exerted is large, erosion failure of front face and shear failure of core occurred.
Numerical Study of Round-Robin Tests on the Split Hopkinson Pressure Bar Technique
Authors: Kariem Muhammad A. , Ruan Dong , Beynon John H.
Published: March 2013

It is known that the split Hopkinson pressure bar (SHPB) technique has not been standardised yet. The standardised SHPB technique is necessary in order to provide guidelines for determining the intrinsic material properties. This paper examines whether consistent results can be achieved from various sets of SHPBs. Finite element analysis has been conducted using ANSYS/LS-DYNA. Numerical simulation of the round-robin tests was conducted to study the consistency of results for OFHC copper, which were obtained from three sets of apparatus, namely: 12.7 mm diameter SHPB made from the AISI 4140 steel, 13 mm diameter SHPB made from the high strength steel (HSS) and 14.5 mm diameter SHPB made from maraging steel 350 (AISI 18Ni). The current study shows that consistent flow stresses (within an acceptable error of 2.5%) were obtained from those three sets of SHPBs, which indicates the possibility of SHPB standardisation in the future.
On the Strength Enhancement of Cellular Materials under Dynamic Loadings
Authors: Xu Shan Qing , Ruan Dong , Beynon John H. , Lu Guo Xing
Published: March 2013

The strength enhancement of cellular materials under dynamic compression was experimentally studied in the present paper. A phenomenological model was employed to investigate the entrapped air contribution by introducing a parameter, namely the leaking rate of air. The strength enhancement caused by the entrapped air was then studied for both aluminum honeycombs and foams. It has been found that the pressure change in the entrapped air during dynamic compression is a direct source of strain hardening for aluminum honeycombs whereas it has smaller influence on the strain hardening of aluminum foams. Other sources that might contribute to the strain hardening of cellular materials are also discussed.
Wave Dispersion and Attenuation in Viscoelastic Split Hopkinson Pressure Bar
Authors: Butt Hafiz Sana Ullah , Xue Pu
Published: March 2013

The Split Hopkinson Pressure Bar (SHPB) is most commonly used facility to obtain material properties at high strain rates. Testing of soft materials using this method requires that bars made of low impedance material should be used, in order to improve signal-to-noise ratio of transmitted stress. However, utilization of such bars poses some difficulties in data processing as the wave dispersion and attenuation becomes noticeable due to their viscoelastic nature. Wave propagation coefficients of a viscoelastic pressure bar are evaluated using incident and reflected strain waves generated through impact of two different length striker bars. Two approaches are proposed for propagation coefficient measurement in this study, namely direct and waves-overlap. Using two approaches, it is found that the calculated attenuation coefficients are same, while the wave numbers are different. The difference in wave number in the case of two approaches is due to the difference in calculated phase change of incident and reflected waves, which is found as integer multiple of 2Π. Moreover, propagation coefficients calculated through different striker impacts are found different. The propagation coefficient found through long striker impact, when used for propagation response prediction of waves generated by short striker impact, resulted in high oscillations in predicted waves.
A Dynamic Constitutive Model of Saturated Remolded Loess
Authors: Xiao Zheng Hua , Liao Hong Jian , Tuohuti Akenjiang , Han Bo
Published: March 2013

A series of dynamic triaxial tests were performed to study a dynamic constitutive relationship of saturated remolded loess under cyclic loading. A new dynamic rational function constitutive model based on damping ratio was proposed. The model assumed the calculated damping ratio equaled to the measured damping ratio and the hysteresis curve was consisted by two curves accorded with rational function. This not only ensured that the theoretical hysteresis curve reflected the real energy dissipation of remolded loess but also retained the high calculated efficiency of this model. The hysteresis curve equation under constant amplitude symmetric loading was deduced and results of this model were verified by the tests.
A Nonlinear Constitutive Model for Soil under Complex Stress State
Authors: Li Hang Zhou , Liao Hong Jian , Han Bo , Song Li
Published: March 2013

It is fundamental to predict the stress-strain behavior of soils to control the stability of the geotechnical engineering. A Duncan-Chang constitutive model is analyzed and found that it ignores the effect of the intermediate principal stress. A unified strength theory is investigated and revised. The lode parameter is introduced into the unified strength theory. The unified friction angle and cohesion which may reflect the influence of the intermediate principal stress and verified by the polyaxial tests are obtained. The compressive strength revised from the unified strength theory is used to replace the Mohr-Coulomb criterion and introduced into the Duncan-Chang model. A modified constitutive model is proposed, which is verified by the plane strain tests. The result shows that the modified constitutive can reflect the effect of the intermediate principal stress, and the Duncan-Chang model is a special case of the modified model when b=0.
Crushing and Flowing Characteristics of Lightweight Foamed Concrete under Different Loading Rates and Temperatures
Authors: Guo Wei Guo , Wang Jian Jun , Li Guang Liang , Shi Ya Jie
Published: March 2013

Lightweight foamed concrete is one kind of new and important runway arresting materials for airplanes and other vehicles. To study its crushing and flowing behavior under different loading rates, an electric-driving screw testing machine, and an Instron VHS 8800 higher strain-rate testing machine are used. Crushing mechanical characteristics, and deformation and failure mode with the density of 0.20g/ccm are systematically analysed, while crushing strain-rate range from 0.001/s to about 102/s. Results show this foamed concrete suffers three stages of deformation during loading, namely elastic region, crushing plateau region and densification region; and it presents very low shear strength. Based on testing results, a phenomenological model is established, and comparing model predictions with experimental results, a good agreement is obtained.
Characterization and Electrochemical Performances of Vanadium Oxide Films Doped with Metal Ions
Authors: Wang Ji Chao , Wu Guang Ming , Gao Guo Hua , Zhou Xiao Wei
Published: March 2013

Vanadium oxide films were prepared via the sol–gel process and dip coating method, using V2O5as raw materials and H2O2(volume fraction 30) as the solvent. Mn and Ni ions were added to vanadium oxide sol to prepare doping vanadium oxide films. The films were characterized by atomic force microscopy, FT-IR, X-ray diffraction and electrochemical techniques. The add-on of Metal ions will not affect the morphology of the vanadium oxide films, but change the valence of vanadium ion and vanadium oxide crystal phase. Furthermore, cyclic voltammetry curves show that metal ions doping vanadium oxide films exhibit reversible electrochemical reaction. But electrochemical impedance spectroscopy indicates pure vanadium oxide film has a better diffusion rate.
Structural Study of WO3 and MoO3 Compound Films in H2 Gasochromism
Authors: Zhang Zeng Hai , Wu Guang Ming , Gao Guo Hua , Feng Wei , Jin Xiao Bo , Shen Jun
Published: March 2013

Sol-gel tequnique was used to prepare disordered tungsten oxide and molybdenum oxide sols. A series ratio of W:Mo compound sols were obtained via mettalic powder co-peroxided by H2O2 as precursors in ethonal. Compound films were achieved by dip-coating method. Fourier Transform Infrared Spectroscopy, Raman Spectroscopy were taken to characterize the structure of these compound films. Uv-visible Spectroscopy was used to test the gasochromic property. The results showed that the gasochromics property was much different from that of pure tungsten oxide and molybdenum oxide sol-gel thin films. The effect was origined from the structrue alteration, which was not due to the spectrum superposition but the co-reaction of W and Mo.
The Study of Microcrystalline Silicon Thin Films Prepared by PECVD
Authors: Li Chun Ya , Zhang Hao , Li Jun , Li Xi Feng , Zhang Jian Hua
Published: March 2013

Under different growth conditions, microcrystalline silicon thin films are deposited successfully on glass substrates by the double-frequency plasma enhanced chemical vapor deposition (PECVD). We report the systematic investigation of the effect of process parameters (hydrogen dilution, substrate temperature, forward power, reaction pressure, et al.) on the growth characteristics of microcrystalline silicon thin films. Raman scattering spectra are used to analyze the crystalline condition of the films and the experimental results. Optimizing the process parameters, the highest crystalline volume fraction of microcrystalline silicon films was achieved. It is found that the crystalline volume fraction of microcrystalline silicon films reaches 72.2% at the reaction pressure of 450 Pa, H2/SiH4 flow ratio of 800sccm/10sccm, power of 400 W and substrate temperature of 350 °C.
Annealing Effect on Reversible Photochromic Properties of Ag@TiO2 Nanocomposite Film
Authors: Zuo Juan
Published: March 2013

Large-scale uniform Ag@TiO2 films was prepared by RF magnetron sputtering in pure Ar plasma using polycrystalline TiO2 semiconductor sintered target. The effect of annealing on the photochromic properties was studied to obtain a better understanding of the interaction of the structure. Ultraviolet-visible absorption and scanning electron microscopy were performed to investigate the possibility of tailoring the structure with consequent modification of the optical properties. Ag nanoparticles were formed between TiO2 films after annealing the samples with Ag film structure. The annealed Ag@TiO2 films present a photochromic property in comparison with the as-prepared samples. Such nanocomposite films can be used as smart windows, high density multiwavelength optical memory and rewritable electronic paper.
High Performance of YBCO Films Prepared by Fluorine-Free MOD Method and a Direct Annealing Process
Authors: Xu Xiang Xue , Xu Wan Chen , Bai Yue Ling , Cai Chuan Bin , Fang Jian Hui
Published: March 2013

Chemical solution-deposited (CSD) is a cost-effective non-vacuum method for YBCO coated conductor fabrication. We developed a new fluorine-free metal-organic deposition (MOD) method with metal acetates, propionic acid and xylene as the starting materials. Using this non-fluorine MOD method, we were able to get high performance YBCO superconducting films within a shortened heat treatment time, which was reduced by at Least 5 h in comparison with that for pyrolysis-annealing non-fluorine MOD process. Superconducting property, with a critial current density (Jc) over 0.55MA/cm2at 77K, self-field has been obtained for 380 nm epitaxial YBCO thin films on (00l) LaAlO3(LAO) single crystal substrate. Owing to the low price of starting materials and shorter heat treatment time, fluorine-free MOD method is a very effective and cost-cutting process.
Study on Special Morphology Hydroxyapatite Bioactive Coating by Electrochemical Deposition
Authors: Gu Cai Ge , Fu Qian Gang , Li He Jun , Lu Jin Hua , Zhang Lei Lei
Published: March 2013

Bioactive calcium phosphate coatings were deposited on carbon/carbon（C/C） composites using electrochemical deposition technique. The effects of electrolyte concentration and constant current density on morphology, structure and composition of the coating were systematically investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transformed infrared (FTIR) spectroscopy. The results show that, the coating weight elevated gradually with the increase of electrolyte concentration, and the morphology of coatings changed from spherical particles to nanolamellar crystals with interlocking structure initially. Then the coating transformed into seaweed-like and nano/micro-sized crystals along the depth direction of the coating. The coatings showed seaweed-like morphology as the deposition current density was less than 20mA. With the less current density, the coating became more homogenous. However, the coating was fiakiness crysal, with needlike crystal stacked upside as the current density reached to 20mA/cm2. The coating weight was improved gradually when the current density increased from 2.5mA/cm2 to 10mA/cm2, then reduced with the increasing current density in the range of 10 to 20mA/cm2.
Corrosion Inhibition and Adsorption Behavior of 4-((2-Thiophenecarboxylic Acid Hydrazide)methylene)benzoic Acid) on Copper Surface in CO2-Saturated Oilfield Water
Authors: Chen Shi Liang , Liu Zheng , Liu Jie
Published: March 2013

The inhibition effect and inhibition mechanism of a 4-((2-thiophenecarboxylic acid hydrazide)methylene)benzoic acid) (HD) against copper corrosion in CO2-saturated oilfield water was evaluated using electrochemical techniques and scanning electron microscopy. The experimental results shown that HD is a good corrosion inhibitor and the inhibition efficiency increased with the increase of HD concentration, and research indicate that adsorption behavior of the HD followed the langmuir’s adsorption isotherm and the adsorption mechanism is typical chemisorption.
TiC-TiB2 Coating on Ti-6Al-4V Alloy Substrate in Graded Composition Achieved by Fusion Bonding and Atomic Interdiffusion under Combustion Synthesis in High-Gravity Field
Authors: Huang Xue Gang , Zhao Zhong Min , Zhang Long , Shi Li Qing
Published: March 2013

Based on fusion bonding of liquid TiC-TiB2 ceramic film and molten Ti-6Al-4V substrate to induce the surface alloying of Ti-6Al-4V substrate, the TiC-TiB2 ceramic coating on Ti-6Al-4V substrate was achieved in graded composition by combustion synthesis in high-gravity field. XRD, FESEM and EDS results showed that TiC-TiB2 ceramic coating was composed of fine TiB2 platelets, TiC irregular grains, Cr metallic phase and a few Al2O3 inclusions. The mechanical properties showed that the relative density, microhardness and fracture toughness of TiC-TiB2 ceramic coating reached 98.5%, 25.8 ± 3.5 GPa and 16.5 ± 2.5 MPa • m0.5, respectively. The fusion-bonding area and heat-affected zone of Ti alloy were obviously observed between the ceramic coating and Ti alloy substrate, and within the fusion bonding area a number of ultralfine TiB platelets and fine Ti-enriched carbides were embedded in the matrix of α’-Ti martensite, whereas at the heat-affected zone of Ti-6A1-4V substrate some C, B atoms were also detected. As a coupled result of fusion bonding and inter-diffusion between liquid ceramic film and molten Ti alloy substrate, followed by TiB2-Ti peritectic reaction and subsequent eutectic reaction in TiC-TiB-Ti ternary system, the ceramic coating of TiC-TiB2 on Ti-6Al4V substrate was achieved in continuously-graded composition, presenting the transitional change in microhardness from the ceramic coating to Ti alloy substrate with high shear strength of 450 ± 35 MPa between the coating and the substrate.
Luminescent Properties of Eu2+, Eu3+ and Dy3+ Co-Activated SrAl2O4 Nanocrystals
Authors: Huang Yuan Ming , Ma Qing Lan , Zhai Bao Gai
Published: March 2013

By the control of the reducing atmospheres in the one-pot combustion reactions, Eu2+, Eu3+ and Dy3+ co-activated strontium aluminate oxide were synthesized. X-ray diffraction confirmed the formation of monoclinic SrAl2O4 nanocrystals. The photoluminescence spectra of the phosphors were measured. It is found that three sharp emissions at 483, 570 and 615 nm were superimposed onto the broad green emission band at about 520 nm. The origins of the broad green luminescent band, the sharp blue at 483 nm, and sharp yellow emissions at 570 nm and the sharp red emissions at 615 nm can be attributed to the 4f65d1→4f7 transitions of Eu2+ ions, the 4F9/2→6H15/2 transition of Dy3+ ions, the 4F9/2→6H13/2 transition of Dy3+ ions, and the 5D0–7F2 transition of Eu3+ ions in the SrAl2O4 nanocrystals, respectively. The results indicate that the white light emitting phosphors are possible by tuning the relative molar percentages of Eu2+, Eu3+ and Dy3+ in the phosphors.
The Synthesis of CaCu3Ti4O12 High Dielectric Ceramics by a Spark Plasma Sintering Method
Authors: Ruan Xue Feng , Yang Zhi , Zhang Yue , Shi Jing , Xiong Rui
Published: March 2013

CaCu3Ti4O12 (CCTO) ceramics were synthesized by a spark plasma sintering technique, and then were annealed in air at different temperatures. The characterization methods including X-ray diffraction, X-ray photoelectron spectroscopy indicated that the composition distribution, the valance of the Ti ions of the CCTO ceramics have great dependence on the annealing temperature, which result in that the dielectric properties of the CCTO ceramics have great dependence on the annealing temperature. The annealing at 500 and 700 °C can enhance the dielectric constants greatly, and the dielectric loss at high frequence (1 MHz) reduces with the increase of the annealing temperature. These annealing-dependent dielectric properties are ascribed to the oxygen vacancies and the holes formed in the sintering and annealing treatment.
Glass-Forming Ability and Thermal Stability of Gd55-xNdxCo20Al25 Metallic Glass
Authors: Zhang Li Li , Huang Qi Jun , Liao Zhi Qin , Xu Feng , Chen Guang , Li Shan Dong
Published: March 2013

The effects of Nd substitution in Gd55-xNdxCo20Al25 (x=0, 5, 10, 15 and 20) amorphous ribbon samples on glass-forming ability and thermal stability are studied. The change of microstructure cannot be identified by X-ray diffraction. The forecast of glass-forming ability following Fang’s method shows the increase with x, which is further confirmed experimentally by the increasing reduced glass-transition temperatures. The thermal stability has a minimum at x=10, and it is suggested to be due to the different effects of the reducing of Gd and the increase of Nd.
Monitoring Technological Conditions for Preparing DLC Films in Supersonic Flow of Hydrocarbon Plasma
Authors: Svitasheva S.N. , Pozdnyakov George A.
Published: March 2013

Properties of diamond-like carbon films deposited by a new method in a supersonic flow of hydrocarbon plasma generated by a disk-type magneto-hydro-dynamic accelerator were studied. Two methods are used for optical and structural characterization of diamond-like carbon films: nondestructive spectroscopic ellipsometry and Raman spectroscopy.
Preparation and Performance of ZnO Based Gas Sensors Working at Room Temperature
Authors: Huang Yuan Ming , Ma Qing Lan , Zhai Bao Gai
Published: March 2013

In this presentation, we present the preparation and performance of ZnO gas sensors on glass substrates. The phase and microstructures of the prepared ZnO nanocrystals were characterized with the X-ray diffractometer and transmission electron microscope. The transient response characteristics of the ZnO based sensors were recorded at room temperatures in saturated ethanol gas. It has been observed that the ZnO sensors can be operated at room temperature.
ZnS-Montmorillonite: An Application as Electrochemical Sensor
Authors: Udkhao Siriphorn , Wongchaisuwat Atchana , Meesuk Ladda
Published: March 2013

Sensors based on clay-modified electrode have been studied extensively. They have been made from different intercalation compounds to determine both organic and inorganic species. Various analytical techniques have been applied for clay-modified electrodes. In this work, we used ZnS-montmorillonite as a sensor to construct an electrochemical electrode or potentiometric electrode by mixing ZnS-montmorillonite with graphite, polytetrafluoroethylene (PTFE) and carboxymethylcellulose (CMC) in an appropriate ratio. It was found that, the electrode gave best response to sulfide ion compared with other ions. The graph plotted between potential in mV against log[S2-] gave slope near 29.5 due to Nernst equation. The pH studied showed that the potential was almost constant at pH 4-11 and pH 4-9 in 0.01 M and 0.001 M of S2- solutions, respectively. This implied that the sensor could be used at a wide range of pH. The electrode also gave good precision.
Modulation of Optical Transmission in Photonic Crystal
Authors: Dong Guo Yan , Zhou Ji
Published: March 2013

The transmission properties of electromagnetic wave (EMW) can be modulated by the periodic structure of photonic crystal (PhC) to bring many novel optical effects. The special distributions of equal frequency contours (EFCs) can be used to control the wavefront state and transmission direction of propagating wave in PhC with some special effects, such as non-handed refraction. Based on the intricate undulation of one single band or the overlap of different bands, the phenomena of dual-negative refraction, symmetrical positive-negative refraction and triple refraction have been achieved in the higher band regions. These unique features will provide us with more understanding of electromagnetic wave propagation in PhCs and give important guideline for the design of new type optical devices.
Synthesis of SnS2/SnO2 Nanocomposite for Visible Light-Driven Photocatalytic Reduction of Aqueous Cr(VI)
Authors: Yang Min , Zhang Yong Cai , Dai Wei Min , Hang Ke , Pan Yue Quan
Published: March 2013

SnS2/SnO2 nanocomposite was synthesized by a simple in situ hydrothermal oxidation route, and characterized by X-ray diffraction, energy dispersive X-ray spectroscopy, transmission electron microscopy and UV-vis diffuse reflectance spectrum. The as-synthesized SnS2/SnO2 nanocomposite displayed much superior photocatalytic activity to SnS2 and SnO2 nanoparticles in the reduction of aqueous Cr(VI) under visible light (λ > 420 nm) irradiation.
Effect of Activated Water Treatment Sludge on Carbonation of Mortar
Authors: Chen Yun
Published: March 2013

Activated water treatment sludge (AWTS) is a newly developed environmentally friendly blending material that contains 12CaO•7Al2O3 and C2S as cementitious minerals. In order to evaluation service performance of AWTS blended cement, carbonation characteristic and microstructure of mortar incorporating 20 wt. % AWTS was studied in present paper. Increasing with carbonated time prolonging under standard test condition, carbonation performance of mortar specimens achieved quality index of class T-Ⅳ of Chinese construction code JGJ/T 193-2009. Compressive strength of carbonated mortar had a little rise compared to controlled mortar cured at standard condition for 28 days. Portlandite reacts with carbon dioxide to form calcite and, calcite reacts with aluminate minerals to form monocarboaluminate. This was confirmed by SEM observation. AWTS has no disadvantageous effect on carbonation of Portland cement. More aluminate in the blended cement resulted in monocarboaluminate type AFm formation. ATWS can be employed as blending material for modern cement industry.
The Influence of Curing Temperature on the Coordination of the Expansion and Strength of High Strength Expansive Concrete
Authors: Feng Jing Jing , Zhou Cui Ling , Sun Yong , Wang Xiao Qing
Published: March 2013

The influence of curing temperature on the relationship between the expansion and the strength was studied. The results showed that under the standard curing condition (20。C), the expansion and strength of the high strength expansive concrete develop unisonously with the prolongation of age. However, under the high curing temperature, there is a conflict between the expansion and strength of the concrete. Elevated curing temperature (40。C) promotes the hydration of expensive agent and cement. However the quickly developing strength of the concrete limits its expansion, and leads to the lowest restricted expansion rate of the concrete at 40。C. But suitable expansion made the microstructure of the concrete denser, which resulted in the highest strength of the concrete at 40。C. High curing temperature (60。C) leads to excessive expansion at early hydration age. Appropriate volume expansion is benefit to the improvement of pore structure of hardened paste by reducing large pores and to increase the strength of the concrete. However, excessive volume expansion is harmful to the microstructure and leads to the lowest strength of the concrete at 60。C.