bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Tetraethoxysilane Infiltration on Properties of 2.5D Quartz Fibers Reinforced Silica
Authors: Wang Hong Sheng , Li Ling , Wang Chong Hai , Li Yong , Wei Qi Hong
Published: April 2010

In this study, 2.5 dimensional quartz fibers reinforced fused silica (2.5D SiO2f/SiO2) composites were prepared by in-situ solidification vacuum-assisted liquid-phase infiltration method using Si-sol and tetraethoxysilane. Composites’ tensile strength and compressive strength were tested by universal testing machine, and the microstructures of the specimen were observed by scanning electron microscopy (FEI Sirion 200). The ultimate sintering temperature was chosen by the differential thermal analysis of tetraethoxysilane gel and the effect of sintering temperature on the composites’ tensile strength. Densification behavior, mechanical properties and microstructures of the composites were investigated. The results show that tetraethoxysilane infiltration process is an efficient route for the preparation of SiO2f/SiO2 composites, after two cycles when the weight was no longer increased using Si-Sol infiltration, the density of SiO2f/SiO2 composites increases from 1.63 to 1.74g/cm3, while the tensile strength and compressive strength, respectively, increase from 31.2 to 52.7MPa and 59.0 to 129.7 MPa. And the interface de-bonding and distinct fibers pull-out of the fracture faces show that it is non-brittle fracture. The enhanced mechanism of tetraethoxysilane infiltration was also analyzed in this paper.
Effect of Sintering Temperature on the Behavior of Oxygen Permeation for La0.6Sr0.4Co0.2Fe0.8O3-δ Tubular Membranes
Authors: Fan Chuan Gang , Wu Ri Ming , Pei Li Zhai , Zhang Qian Feng
Published: April 2010

La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) tubular membranes with relative density more than 95% were prepared using plastic extrusion method, and their oxygen permeation properties were characterized in steady state. It was found that the permeation properties were influenced apparently by the sintering temperature for the resulting LSCF membranes. The as prepared LSCF membrane sintered at 1300oC had a permeation rate by 5~6 times higher than that sintered at 1250oC. The XRD results showed that the as prepared LSCF membrane sintered at 1250oC had the content of impurity more than that sintered at 1300oC. Namely the reasonable elevation of sintering temperature can reduce the impurity in LSCF membranes, which was produced during green process, and the effect of impurity reduction can improve the transport capability of LSCF membranes made by plastic extrusion.
Proton Transport in Nafion117 Membranes by Molecular Dynamics
Authors: Wu Tie Jun , Wu Yu Hou , Sun Hong , Tang Yu Lan
Published: April 2010

A molecular dynamics model was performed to study the proton transport of Nafion series membrane which is often used in low temperature fuel cells. The simulations intents to investigate the microstructure and the phenomenon of the proton transport processing. The model includes all-atom of main and side chains. The force field includes intermolecular Coulomb and Lennard-Jones terms and intra-molecular terms for harmonic bond stretch potentials, harmonic angle bend potentials and cosine terms for the torsions. The simulations were carried out in two cube systems at different temperature where water content differed from 5 and 10 water molecules per acid group in the polymer, respectively. The results showed that proton transport affected with water content by analyses of snap- shots of the MD simulation, the radial distribution functions between the sulfur atoms of SO3− groups, between the oxygen atoms of H3O+ ions, between oxygen atoms of water molecules and Nafion atoms at various stages.
Synthesis and Characterization of the Cathode Materials La0.7Sr0.15Ca0.15Co1-yFeyO3-δ for ITSOFC
Authors: Gao W.Y. , Hu Z.Q. , Sui X.G. , Li C.M. , Tang N.L. , Cao H.L.
Published: April 2010

La0.7Sr0.15Ca0.15Co1-yFeyO3-δ(LSCCF)powders with 0.2y0.5 for the applications as the cathode materials in intermediate temperature solid oxide fuel cell(ITSOFC) were synthesized by glycine-nitrates-process(GNP) using metal-nitrates and glycine as the raw materials. The process, crystal structure and particles morphology of the powders calcined at 600°C,800°C,1000°C for 3h were characterized by IR,XRD and SEM. The experimental results show that co-doped Ca2+ and Sr2+ replacing some La3+ in A site and Fe3+ replacing some Co3+ in B site didn’t influence the formation of perovskite structure and the powders calcined at 800°C for 3h were high pure single perovskite state. The electrical conductivity of LSCCF samples sintered at 1200°C for 3h,was measured as a function of temperature from 100°C to 800°C by the four-probe DC method in air.As a result, the conducting mechanism of LSCCF is p-type small polaron hopping process, and the electrical conductivity are all higher than 100 S/cm. But the electrical conductivity of LSCCF samples increase with Fe3+ content decrease.
Preparation and Characterization of ZrO2 Nanopowders for Solid Oxide Fuel Cells
Authors: Chen Yun Xia , Gu Xing Yong , Cao Chun’e , Huang Yang
Published: April 2010

ZrOCl2•6H2O and Y(NO3)3 were used as raw materials to fabricated Y2O3 stabilized ZrO2(YSZ) nanopowders by hydrothermal method. The addition of Y2O3, different precipitants, different hydrothermal temperatures and times were studied. XRD and TEM were employed to characterize phase compositions, grain sizes and lattice parameters of the as-prepared YSZ nanopowders. The results show that less than 10nm and well crystallized cubic YSZ were obtained under a certain experimental conditions. Different precipitants affect the formation of precursors and final products. The addition of NaOH is benefit to the growth of YSZ crystals with the max grain size and the minimum lattice distortion among the three kinds of precipitants. Amorphous YSZ powders are obtained at lower hydrothermal temperature of 150°Cfor longer treating time of 6h. However, when the hydrothermal temperature is elevated at 180°C, well crystallized YSZ powders are prepared only treated for 2h.
Synthesis and Electrochemical Properties of 0.5Li2MnO3•0.5LiMn0.5Ni0.5O2
Authors: Zhong Sheng Wen , Hu Wei , Zhang Qian
Published: April 2010

The precursor of Mn0.75Ni0.25CO3 is prepared by carbonate co-precipitation method. And the cathode material 0.5Li2MnO3•0.5LiMn0.5Ni0.5O2 is synthesized with two stages calcining temperatures T1 and T2. T1 represents 400°C, 500°C, 600°C and T2 is selected at 750°C, 850°C, 950°C respectively. XRD Patterns shows that the cathode material has the integrated structures of Li2MnO3 and LiMO2, and it has better crystallization during the rise of calcined temperature at 950°C. The electrochemical performances tests indicates that the initial discharge specific capacity are greater than 220mAh/g at the current density 0.2 mA/cm2 in 2.5-4.6V at room temperature. When cathode material is calcined at 750°C, its discharge specific capacity even reach to 248mAh/g, but the cathode material has more perfect general electrochemical properties during calcined temperature at 950°C.
Synthesis of the Layered-Spinel Intergrowth Structure Cathode Materials by Co-Precipitation Method
Authors: Feng Yu Chuan , Zhao Shi Xi , Nan Ce Wen , Lin Yuan Hua
Published: April 2010

Cathode materials Li-[MnxNi1/2-x/2Co1/2-x/2]-O (x=0.333, 0.4, 0.6, 0.8, 0.9) were fabricated by lithium salts (LiNO3) and manganese-nickel-cobalt hydroxide precursors using the required amounts of Mn, Ni, Co for a given value of x. When Mn content is between 0.5 and 0.8, layered and spinel structure co-existed. Meanwhile the rate Li/M is also a key factor for synthesis of layered-spinel intergrowth structure cathode materials without other impurities. Li-[Ni0.2Co0.2Mn0.6]-O and Li-[Ni0.1Co0.1Mn0.8]-O were synthesized by a Two-step Co-precipitation method.
Fabrication of Graded WC-Co Cemented Carbides by a Lamination Method
Authors: Cheng Ji Gui , Zhu Jin Chuan , Wan Lei , He Hai Gen
Published: April 2010

WC-Co tapes with different Co contents were prepared by rolling the mixtures of WC-Co powders and polymer binders, and layered WC-Co green compacts with discontinuous distribution of Co contents were obtained by laminating the green WC-Co tapes together. After burning off the binders and other organic composition in H2 atmosphere, the green compacts were sintered in vacuum. Microstructure of both the green and the sintered tapes were observed by scanning electron microscope. An electron probe microanalyser was used to measure the linear distribution of Co element in the layered WC-Co cemented carbides. Sintering densification and mechanical property of the multilayered WC-Co alloys were also investigated and compared with those of conventional WC-Co alloys with nominal Co contents of 8% and 12%, respectively. It was shown that by controlling sintering temperature and time, a continuous graded distribution of Co composition can be realized in the laminated WC-Co alloys, with more Co-rich phase in the original high Co content side (12%). Furthermore, the graded WC-Co cemented carbides can realize a combination of high hardness and high strength.
Fabrication and Characterization of Large Size Anode Substrate of Solid Oxide Full Cell
Authors: Zuo Ning , Zhang Mi Lin , Huang Jian Bing , Zhang Li , Mao Zong Qiang
Published: April 2010

The porous NiO/ samaria doped ceria (SDC) cermets, which have been used as the anode-supported for solid oxide fuel cell (SOFC), are fabricated via the tape casting process. In this article using different kinds of slurry system, prepared the large size (60×60mm) anode substrates for SOFC successfully. Effects of solvent, dispersant, plasticizer, binder and the sintering temperature program were investigated. Experimental results show that thicknesses and pore rates of anode substrates are 0.6 ~ 1.5mm and 20% ~ 40% respectively. And all of the complete and flat anode substrates have highly support intensity, for their homogeneous microstructure and pore distribution. Sintering the green pieces of anode substrates at the temperature of 1300°C for 2h, different green pieces have different shrinkages that could be from 20% to 30% measuring with thermal dilatometer. Using this kind of anode substrate, could find out a perfect one to matching the electrolyte film easily.
Preparation and Characterization of SiC/MoSi2 Composites from Powder Resulting from a Mechanical-Assistant Combustion Synthesis Method
Authors: Xu Jian Guang , Li Hui Qiang , Zhang Hou An
Published: April 2010

SiC reinforced MoSi2 composites have been successfully prepared by pressureless sintering from mechanical-assistant combustion synthesized powders. The sintering temperatures and holding time were 1500°C~1650°C at a heating rate of 10K/min and 1 hour, respectively. The microstructure and mechanical properties of the as-sintered composites were investigated. SEM micrographs of SiC/MoSi2 composites showed that SiC particles were homogeneously distributed in MoSi2 matrix. The Vickers hardness, flexural strength and fracture toughness of the SiC/MoSi2 composites were up to 15.50GPa, 468.7MPa and 9.35MPa•m1/2, respectively. The morphologies of fractured surface of the composites revealed the mechanism to improve mechanical properties of MoSi2 matrix. At last, the cyclic oxidation behavior of the composites was discussed. The results of this work showed that in situ SiC/MoSi2 composite powder prepared by MASHS technique could be successfully sintered via pressureless sintering process and significant improvement of room temperature mechanical and anti-oxidation properties could be achieved.
A Novel Biomass Gasifier for Producing Tar-Free and Hydrogen-Rich Syngas
Authors: Tang Zhi Guo , Ma P.Y. , Cheng J.P. , Li Y.L. , Lin Q.Z.
Published: April 2010

Hydrogen from biomass gasification is reviewed as one of the promising clean energies approaches in the future for fuel cell. However, the syngas from biomass gasification usually contains a certain amount of tar, which could not only decrease the efficiency of gasification process and hydrogen production, but also condense as a dense mixture and impose a series of serious problems. So “Excess Enthalpy Gasification (EEG)” is put forward and applied into biomass gasification and a novel biomass gasifier is presented for the purpose of tar-free and hydrogen-rich syngas in this work. The structure characteristic of the gasifier and tar conversion characteristic are analyzed detailedly to prove the feasibility and excellence performance for producing tar-free and hydrogen-rich syngas from biomass gasification.
Grain-Size Characteristics of Mullite Nanocomposites Prepared by Open-System Hydrothermal Crystallization Method
Authors: Chen Nan Chun , Ao Han Mei , Li Quan Hong , Tang Quan
Published: April 2010

In this research, raw kaolin is processed by oxidation-reduction fining method and then baked to produce mullite precursor, which can prepared multi-phase mullite nanocrystals at low temperature hydrothermal conditions under normal pressure. According to the analysis of the controlling factors of NaOH mole ratio in the hydrothermal system, reaction temperature, holding time and the precursor concentration, etc., we studied the effect of above-mentioned factors on the grain size of product. The results show that when NaOH concentration 3mol/L, hydrothermal reaction temperature 80°C, holding time 3 h, precursor concentration 0.15g/ml, the morphology of the prepared nanocomposite with grains size of 60 ~ 90nm appears spherical-like, also the uniform dispersion can be acquired.
A New Method of Producing High Purity 4A-Molecular Sieve from High Modulus Sodium Silicate Liquor Purified by Carbonization
Authors: Bai Guang Hui , Xu Peng , Teng Wei , Wang Xiang Gang
Published: April 2010

A new technology for producing high purity 4A-molecular sieve was developed with high modulus sodium silicate liquor and sodium aluminate liquor extracted from coal fly ash as starting materials. The sodium silicate liquor extract was purified by precipitating ferrous, titanium, and other impurities by carbon dioxide injection. Concentration of carbon dioxide in the extract was maintained at 48%, and the pH value of the extract controlled in the range of 11 and 11.2. After that, the purified sodium silicate liquor was mixed with sodium aluminate liquor in the ratios of SiO2/Al2O3=2.0, Na2O/SiO2=1.6 and H2O/Na2O=60. The mixture was then heated to 90°C and kept for 2 h. A high purity 4A-molecular sieve product was obtained after washing and drying the crystals obtained from the reaction mixture. The molecular sieve product has a purity of 99% and aperture of 0.4nm. Its calcium absorption capacity is about 290mg/g. The product was also characterized by SEM, BET, XRD and IR analysis.
Application of DSC Technique in Study of Glass Ceramic
Authors: Qu Li Jie , Li Bin , Wang Jing , Gu Yue Mei
Published: April 2010

Glass-ceramics with desired microstructures and properties are controlled by nucleation and crystallization. The nucleation and crystallization of glass, which include the nucleation, crystal growth rates and the activation energy, are important in understanding the stability of glass in practical applications. The activation energy of crystallization (E) plays an important role in determining the utility of glass ceramic. The amorphous to crystalline transformation in glass can be investigated by isothermal and non-isothermal method which is differential scanning calorimetric (DSC). In the isothermal method, the sample is measured as a function of time, while in the non-isothermal method the sample is recorded as a function of temperature. An advantage of the non-isothermal method is the possibility of reaching a test temperature instantaneously and during the time, which system needs to stabilize. However, the isothermal method does not have this advantage. In the present work, this technique was used to calculate the activation energy of CaO-Al2O3-SiO2-CeO2 glass-ceramics. DSC technique can be used as to determine the optimum heat treatment temperature. The advantage of the DSC technique in study of glass-ceramics is that it requires much less time.
Effects of Starting Carbon Sources on the Carbothermal Synthesis of SiC Powders
Authors: Cheng Jun Hua , Wen Di Jiang
Published: April 2010

Silicon carbide (SiC) powders have been prepared at 1200–1500°C by carbothermal reduction of two kind precursors of carbonl/silica mixtures: coked rice husk with high-carbon content, and gasified rice husk with low-carbon content mixed with carbon powders as an external carbon sources. The differences in nature of carbon matter in the external source and coked rice husk, and their effect on SiC synthesis have been studied by TG-DSC, TEM, XRD and laser diffraction technique. Experimental results show that the difference in nature of carbon source may affect the formation of SiC powders. The characteristics of the synthesized SiC particles strongly depend on the characteristics of the carbon sources.
Preparation of Nanometer Mullite via Supercritical CO2
Authors: Li Jin Hong , Ma Hong Wen , Cao Ying
Published: April 2010

The xerogel of mullite precursor with high specific surface area (422m2•g-1) was successfully prepared from the sol of aluminium isopropanol (AIP) and tetraethyl orthosilicate (TEOS) tuned by supercritical CO2 and subsequent supercritical fluid extraction. Nanometer mullite was prepared by calcining the xerogel of the precursor, and the obtained mullite together with the xerogel precursor was characterized by SEM, XRD, N2-adsorption and IR. The results showed that the xerogel precursor exhibit a shape of amorphous structure, with size of no more than 100 nm, and no huge blocks was found, indicating that the supercritical CO2 plays an important role in controlling the process of hydrolyzation, sol-gel transition, in which supercritical CO2 may promote the mixture of Si and Al on atomic scale. SEM indicated that the obtained mullite were mainly 2-3 μm in length and lath in shape with aspect ratios of 6-10, and the laths were interlaced with each other to construct a relative dense mullite aggregation. The mineralogical phases tracing experiment showed that the mullitization process underwent from 1200 °C to 1400 °C as followed by the phase transition from -Al2O3 to -Al2O3, and to -Al2O3, and the temperature of complete phase transformation into mullite was 1400 °C.
Effect of Nucleating Agents on Crystallization Glass Ceramics Produced from Nickel Slag
Authors: Wang Yali , Wang Lin Jun , Ma Ming Sheng , Ni Wen , Feng Yun Sheng
Published: April 2010

A laboratory preparation process of glass ceramics from nickel slag was introduced. The controlled heat treatment processes were carried out on the basis of differential scanning calorimetric (DSC) measurements. Mineral phase and microstructure of crystallized glass were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The modified Kissinger equation was employed to investigate the crystallization kinetic parameters, activation energy E and the k(Tp). The Avrami exponent, n, was calculated by Augis-Bennett equation. Analysis indicated that the glass with 10%TiO2 added was peril to crystallize, of a large value of k(Tp), its k(Tp) is 0.244, E is 522.76kJ/mol and n is 3.42. The crystal phase is diopside.
Preparation of Rutile Crystalline Glaze
Authors: Xia Yin Feng , Huang Zhao Hui , Yuan Jia Zheng , Wang Lin Jun , Xie Jie Hua
Published: April 2010

Crystalline glaze is a kind of art glaze with excellent decorative performance, the existing crystalline glaze mainly willemite crystalline glaze, systems on a single track. In this paper, the use of crystalline glaze raw materials for glass, ZnO and coke gemstones, CuO as coloring agents, using ortho- gonal to determine the formula, this paper researched that added TiO2 to the willemite crystalline glaze crystal phase composition as well as the amount of TiO2 and processing conditions on the preparation of crystalline glaze crystal flower morphology impact. The results show that under the conditions of 1250°C melting 1130°C crystallization process crystal spontaneous growth in crystalline glaze can be able to cover the entire glazed, shape of crystals was feathered, cross growth, the number of crystal increased with crystallization temperature, glaze was smooth and shiny sense. XRD and optical microscopy analysis showed that the precipitation of crystals was the long column of rutile, crystal distributed equality, under a polarizing microscope in purple, green and black, with strong aesthetic values.
Preparation of High-Purity Alumina by Hydrolyzing High-Purity Metal Aluminum
Authors: Liang Liu Jian , Hu Jin , Jun Wang Kai , Qin Zhu Xiao
Published: April 2010

This paper puts forward a new method for the preparation of 99.999% high-purity alumina used for the LED underlay sapphire, which has above 99.999% high-purity aluminum atomized the active aluminum powder by the supersonic multistage cooling way, then makes the powder form the hydrate of the alumina through the hydrolyzing reaction, and finally gets 99.999% high-purity alumina by means of the calcinations and the follow-up granularity treatment. By the processing way, the reactant is only aluminum and water, and there is no other additive, which profitably keeps the product pure and completely satisfies the requirements of synthetic crystals while tested.
Effect of Sodium Dodecylbenzenesulfonate on Dispersion of SiO2 Nano-Powder in Aqueous System
Authors: Liu Ji Yan , Ma Shi Ning , Qiu Ji , Suo Xiang Bo
Published: April 2010

Good dispersing stability is required for nano-SiO2 which, however, tends easily to conglomerate, to be widely applied as an important functional material of high toughness, high resistance to corrosion and good high-temperature performance. Through ultrasonic treatment, the suspension of SiO2 nano-powder in water was prepared utilizing sodium dodecylbenzenesulfonate (SDBS) as the dispersant. The effect of SDBS content and ultrasonic treatment time on the suspension stability was investigated by way of testing the particle size of SiO2 nano-powder, the Zeta potential and transmittance of the suspension. The results show that with increasing SDBS content, the particle size of SiO2 nano- powder decreases and then increases, which is similar to the case of increasing the ultrasonic treatment time. With optimum SDBS content, the suspension of SiO2 nano-powder possesses a good dispersing stability due to the existence of electrostatic and steric effects resulting from the particular structure of SDBS. The optimum dispersing condition is SDBS of 1.6 wt% with the ultrasonic time of 18 min.
Preparation of Ternary Rare Earth Sulfide LnxGd2-xS3 (Ln: La, Tb)
Authors: Yuan Hai Bin , Yi Wei Xin
Published: April 2010

We investigated the formation behavior of ternary rare earth sulfide LnxGd2-xS3 (Ln: La, Tb). Ternary rare earth sulfide LnxGd2-xS3 (Ln: La, Tb) was synthesized via the sulfurization of their commercial oxide powders using CS2 gas for short sulfurization time. It was found that ternary rare earth sulfide LnxGd2-xS3 (Ln: La, Tb) could be synthesized for a short sulfurization time of 3 h at 1100°C. For LaxGd2-xS3, it crystallizes in α phase (Orthorhombic phase), the crystal structure is different from rare earth sulfide La10S14-xOx which crystallizes in β phase (Tetragonal phase) but is same with rare earth sulfide α-Gd2S3. TbxGd2-xS3 also crystallizes in α phase, the crystal structure is same with rare earth sulfide α-Tb2S3.
Preparation and Photocatalytic Properties of Fe-Doped TiO2 Nanocrystalline Composite Particles
Authors: Liao Hai Da , Ma Jin Lie , Dai Jian
Published: April 2010

Metatitanic acid was adopted as the raw material to prepare Fe-doped TiO2 nanocrystalline composite particles using suspension polymerization and sol-gel method, which were then characterized with XRD, TEM, TG-DTA and IR, etc.. The results showed the samples were nanocrystal accumulated porous particles, with average particle size of 29nm. Through doping of Fe3+ ion, the photo catalytic activities of particles under Xe lamp were investigated by photodegrading the methyl orange. It was found that, the TiO2 nanocrystal doped with 0.5% Fe3+ ion (accounted as mass fraction) had the highest catalytic activity. The Fe-doped TiO2 nanocrystalline composite particles prepared in this study has high activity, is easy for separation, recovery and reuse.
Nanometer SrTiO3-Supported Ni-Based Catalyst in the Reaction of CO2 Reforming CH4 to Syngas
Authors: Wang Chun Feng , Gu Hua Zhi , Chen Hao
Published: April 2010

Superfine nanometer SrTiO3 with size of near 50-60nm was prepared by citrate process and sol-gel method. XRD and TEM characterizations indicate that sol-gel method is appropriate to prepare high-purity powders at far lower temperature than other methods. The Ni-based catalysts were prepared by using SrTiO3 powder as support through impregnation and sol-gel method. These catalysts were applied to the reaction of CO2 reforming CH4 to synas and showed high activity. The catalytic activity of Ni-based catalyst is investigated by reaction temperature, the method of support preparation, and the method of catalyst preparation; It shows that the catalyst possesses higher catalytic activity with the increasing of temperature; and the catalytic rate is near 90% at 973 K; and the catalyst show higher catalytic activity when support is prepared by sol-gel method than by citrate process; and the catalyst shows better catalytic activity when catalyst is prepared by sol-gel method than by impregnation method.
Luminescence Properties of (MxMg1-x)2SiO4:Dy3+, Eu3+ (M=Ca, Sr, Ba)
Authors: He Da Wei , Zhou Xin Rong , Wang Yong Sheng
Published: April 2010

A series of phosphor of (MxMg1-x)2SiO4: Dy3+, Eu3+ (M=Ca, Sr, Ba) were synthesized by high temperature solid-state reaction method and studied. The structure and emission spectrum excited by near violet light were investigated. The excitation spectra of single-doped (MxMg1-x)2SiO4: Dy3+ show strong absorption near 322nm, 347nm, 362nm and 391nm due to 6H15/2→4I9/2, 6H15/2→6P5/2, 6H15/2→4F7/2, 6H15/2→4G11/2 transition of Dy3+. The emission light is at about 469nm, 474nm, 483nm and 494nm under 391nm UV excitation. In order to obtain white light emission, (MxMg1-x)2SiO4: Dy3+, Eu3+ (M=Ca, Sr, Ba) were prepared to enhance the red light emission.
α-Al2O3 Flake Pink Powder Synthesized by Molten Salt Method
Authors: Zhang Qian , Zhong Sheng Wen , Wang Yu Xiang
Published: April 2010

In the paper, the flaky alumina was synthesized using Na2SO4-K2SO4 as flux by the molten salt method. The mole ratio of molten salt to alumina, temperature of synthesis and the amount of Cr3+ were investigated. The size of flake alumina was analyzed by laser sizer, the phases of the reaction products and the microstructures at different Cr3+ doping content was ascertained by XRD and the surface of flake alumina was observed by SEM. The alumina with two-dimensional planar structure, a large aspect ratio and adapting to preparation of pearlescent pigment was synthesized under the mole ratio of molten salt to alumina between 4 to 5 , the synthesis temperature about 1200°C, the heat preservation time in 4h and the mole amount of Cr2O3 about 2%.
Shear Thinning and Thickening of Alumina Suspensions
Authors: Lu Xiang Yang , Zhang Li Ming , Huang Yong
Published: April 2010

The rheological behavior of alumina suspension stabilized with Tri-ammonia citrate (TAC) was studied. It was thought that there would form some particle clusters due to the collisions between particles caused by their relative motion in the suspension, and such particle clusters are classified as thermodynamic clusters and hydrodynamic clusters by their origin. Shear thinning is the result of decomposition of the thermodynamic clusters, while shear thickening is the result of formation of the hydrodynamic clusters. From the view of cluster-forming potential barrier, it was deemed that the viscosities of alumina suspensions at low and high shear rates are respectively determined by zeta potential and Stern potential on the particle surface, and shear thickening behavior can be suppressed with some excessive TAC.
Synthesis and Photocatalytic Performance of Novel Visible-Light-Driven Bi2WO6 Photocatalyst via a Reverse Microemulsion Process
Authors: Ge Lei , Zhang Xian Hua , Liu Jing
Published: April 2010

The novel visible-light-driven Bi2WO6 photocatalyst with orthorhombic structures was synthesized via a reverse microemulsion method. The as-prepared Bi2WO6 samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM). The photocatalytic activity of the Bi2WO6 powders was determined by degradation of methyl orange molecules in water under visible light irradiation (λ>400nm). The results revealed that the particle and crystallite sizes of the Bi2WO6 powders significantly depended on the synthesis temperature of the reverse microemulsion solutions. The photocatalytic tests indicated that the synthesis temperature also can significantly affect the visible light driven photocatalytic activities.
Hydrothermal Synthesis of Xonotlite Fibers and Investigation on their Thermal Property
Authors: Liu Fei , Zeng Ling Ke , Cao Jian Xin , Zhu Bo , Yuan An
Published: April 2010

A hydrothermal route for preparing large size xonotlite fibers without special instruments and synthesis conditions was development. Effect of pH values in system on the crystal phase and morphology of synthesized xonotlite fibers was studied by using XRD and SEM. The results indicated that the different pH systems have little effect on the crystallinity of synthesized xonotlite, but have great impact on the morphology of xonotlite fibers. The higher pH value is, the lager scale xonotlite fibers appear when the pH values are among 12.0, 12.5, 13.0 and 13.5. The formation of xonotlite fibers was promoted and xonotlite fibers with 10-30 μm in length and 100-200 nm in diameter were prepared at 220 °C for 15 h in the system of pH 13.5. The evaluation of thermal property revealed that synthesized fibers were excellent in thermal stability at high temperature, and could be potential candidate as reinforcement reagents in composite areas.
Elongated Grain Growth Mechanism of Alumina Ceramics with Additives
Authors: Zhu Yong Chang , Rong Shou Fan , Guo Ji Wei , Li Jun Gang
Published: April 2010

The elongated grain evolution of alumina ceramics doping with Al2O3-CaO-SiO2(CAS), Nb2O5, and 3Y-TZP was studied under pressureless sintering. From in-situ growth elongated grain cooperating with second phase to toughen the alumina ceramics, microstructure and sintering properties were firstly studied systematically. The effect of additives on the alumina ceramics with columnar grain were analyzed by means of TEM, SEM, XRD, etc. Basing on the analyzed sintering process by the principle of dynamics, the elongated grain growth mechanism was further studied.
Super Thermal Insulating SiO2 Cryogels Prepared by Vacuum Freeze Drying
Authors: Su Li Fen , Miao Lei , Xu Gang , Tanemura Sakae
Published: April 2010

Traditionally, silica aerogels with low thermal conductivity are prepared by supercritical drying, however, the process is expensive and hazardous due to it run in autoclaves. In order to overcome these disadvantages, a cheaper and safer process, drying at ambient pressure has been developed for decades, but tedious repetitive gel washing and solvent exchange steps are involved. Therefore, in the present study, a novel vacuum freeze-drying was utilized to prepare the super thermal insulating SiO2 cryogels. The wet gels were synthesized via acid-base catalysis using tetraethoxysilane (TEOS) as a silica precursor and ethanol as a solvent. After vacuum freeze drying, nanoporous SiO2 cryogels with low density in the range of 0.08-0.15 g/cm3 were obtained.
Influence of Holding Time on the Properties of Alumina-Aluminium Titanate Fiber
Authors: Zhou Jian Er , Hu Xue Bing , Wang Shuang Hua , Wang Yong Qing , Zhang Xiao Zhen
Published: April 2010

Using aluminum chloride, aluminite powders and butyl titanate as raw materials, alumina- aluminum titanate fiber was prepared by sol-gel method at 1200°C. The influences of the holding time on the aspect ratio, the bulk density, the thermal conductivity coefficient and the heating linear shrinkage of the fiber were studied systemically. The results show that the holding time has an important effect on the properties of the fiber. With the increase of the holding time from 0 h to 3 h, the aspect ratio of the fiber decreases from 870 to 210 and the bulk density of the fiber adds from 352 Kg•m-3 to 432 Kg•m-3. Furthermore, the thermal conductivity coefficient of the fiber keeps rising from 0.162 W•m-1•K-1 to 0.199 W•m-1•K-1 and the heating linear shrinkage of the fiber decreases from 2% to 1.82%.
Computer Simulation and Depth Profiling of Light Nuclei by Nuclear Techniques
Authors: Pacheco de Carvalho J.A.R. , Pacheco C.F.F.P.R. , Reis A.D.
Published: April 2010

This article involves computer simulation and surface analysis by nuclear techniques, which are non-destructive. The “energy method of analysis” for nuclear reactions and elastic scattering is used. Energy spectra are computer simulated and compared with experimental data, giving target composition and concentration profile information. The method is successfully applied to depth profiling of 18O and 12C nuclei in thick targets through the 18O(p,α0)15N and 12C(d,p0)13C reactions, respectively. Similarly, elastic scattering of (4He)+ ions is applied to determination of concentration profiles of O and Al for a thick target containing a thin film of aluminium oxide.
Environmental, Energetic and Economic Analysis about the Energy Source for a Vehicle with Typical Portuguese Urban Use
Authors: Dias André M. , Barros João C.S.S. , Serrano Luís M.V.
Published: April 2010

The main motivation for the present work was the idea to project and build a car, with a hybrid source of power, based on an electric engine, a group of batteries and a source of energy that can be a combustion engine with an electric generator, a fuel-cell or other. The main use of this vehicle was on an urban circuit, but allowing it to make broader circuits. The purpose of this task was to select, with a sustained study, what are the solutions for the source of energy for that kind of vehicle, considering the environmental, energetic and economical perspectives.
The main project idea was to make a hybrid vehicle, with a higher autonomy than a simple electric vehicle, with a lower consumption as possible, and as cleaner and quiet as an electric vehicle can be. With this idea in mind, the future user can have an economic vehicle, with lower pollution emissions which can be used also in other voyages, because it has higher autonomy and can be refuelled more easily.
In order to achieve the objectives of this work, it was made a research about the life cycle impacts considering several possible energetic choices. Based in three different international studies it was tried to make the proper connection to the Portuguese reality. This involved the extrapolation of the results obtained for other possibilities not mentioned as, for instance, the impact of the electricity production, based in the Portuguese data.
For the energetic analysis, several scenarios were made, based on the higher heating value of the different fuels possibilities and on the thermal efficiency of different technologic arrangements. It was made a consumption determination, and a comparative analysis could be done for the several hypotheses that were at stake.
Assuming a typical urban vehicle, with places for four persons, and taking into account the actual vehicles reality, the determination of the fuel consumption of that kind of vehicle were made, with similar weight and dimensions characteristics. This evaluation gives the total energy necessary for a vehicle of this kind and the percentage of electric energy that can be saved and also the percentage that has to be used. This can give the quantity of energy that has to be produced to assure that the car can move in urban and extra-urban typical journeys.
Considering the energy consumption and how much it costs and the market price for engines, it is possible to make an economical analysis for the several possibilities.
Taken into account the several results obtained, for the different choices that were object of the present study, it could be concluded about the choice for better source of energy to generate electric energy for propulsion to the hybrid vehicle.
Radiation Safety of Old Uranium Mining Waste Dumps in Portugal
Authors: Carvalho Fernando P. , Oliveira João M. , Malta Margarida
Published: April 2010

The risks associated to uranium mining and milling wastes require the radiological surveillance of the areas with these residues and the assessment of the radiation risk to the populations living in the region. This radiological surveillance is based on an environmental monitoring programme implemented by ITN. Annually, soils, water, and plants including horticulture products from the uranium mine areas are sampled and analyzed for radioactivity. As part of this programme, analyses of soils, irrigation waters, agriculture products (lettuce), green pasture, and cheese were performed in samples collected in the area of the old Urgeiriça uranium mine and milling facilities near Viseu, Centre-North of Portugal, in order to assess the transfer of uranium series radionuclides to man. In the Urgeiriça area, some soils and vegetables display radionuclide concentrations higher than in reference areas 226Ra was the radionuclide more concentrated by vegetables. Through ingestion of these products 226Ra may be the main contributor to the increment of radiation dose received by local population. The solutions implemented for environmental remediation of tailings piles and mining waste dumps in Urgeiriça and in other old uranium mine sites, with time are expected to render safe these areas and to allow the release of old mining concession areas for other uses by the public without radiation risks.
Recovery of Degraded Areas in Vale do Paraíba, São Paulo, Brazil: Performance Indicators
Authors: de Aquino-Silva Maria Regina , Simão Marcos Roberto , da Silva Santos Denise , de Brito Bastos Eduardo Jorge
Published: April 2010

The aim of restoration is recompose a new vegetation structure in order to obtain benefits such as the containment of bank erosion, reestablishment of a hydric and nutrient regime, and increase the diversity of species. The present paper evaluated the development of the vegetation introduced as ciliar forest around a mining lagoon through establishing indicators based on the vegetation structure, physic-chemical characteristics of the soil and the water. Results show that the indicators of vegetation, like dying of species and the covering of top were classified as negative factors. Regarding vegetation development, it was considered positive when individuals out of inundation points were analyzed. According to soil indicators, chemical factor pH acid suggests intoxication by aluminum, iron and manganese impeding development of the vegetation in the local. Topographic factor also caused erosion and dying/extinction of species localized in declining points and carried nutrients to the inundation point and finally to the sand mining pool.
Surface Wave Energy Capture System (A New Proposition)
Authors: Padrón Armas Isidro , Arvelo Valencia Francisco , Franquis Vera Iballa , Morales García Marcos , García García Feliciano , Avila Prats Deivis
Published: April 2010

Perhaps you have wondered, while lying on the beach or in a boat and feeling the strong pull of the waves or tides, whether it would be possible to harness all that power to produce electricity, just as we do with other elements of nature. This idea is hardly original: the first patent for wave energy was presented in France in 1799, although it was not until the early 70's of the previous century that the idea gave rise to projects funded by companies and governments like Japan and the UK.

However, the slow development of technology and the enormous costs were crippling some projects that have resurfaced in the last five years. More and more governments and companies are beginning to invest in this type of energy, aware that renewable energies may be the key in helping to avoid problems such as pollution and the scarcity of energy resources, and supported by technological advances. The European Union, where the Atlantic Ocean, the North Sea and the waters surrounding the Scandinavian countries have ideal conditions, is also taking the lead in these types of projects. In fact, the Scottish island of Islay boasts the first European turbine that works with wave motion to generate power for 400 homes.

Currently, there are a dozen ways to obtain electricity from wave motion at different stages of development, and with no certainty as to which may become the final one. Basically, they can be divided into two types. On the one hand, those that take advantage of the horizontal movement of the waves and that follow the same principle used in hydroelectricity: channelling the waves through structures of pipes that carry water to a tank located on land, which feeds a system of turbines that generates electric power. In the other group we can find methods based on the vertical oscillations of the waves. The energy of the tides is converted into electricity in tidal power stations, which operate like a traditional river reservoir. The tank becomes filled with the tide and the water is retained until low tide to be released later through a network of narrow channels increasing the pressure until it reaches the turbines that generate electricity. The problem is that high maintenance costs slow their proliferation.

Despite these promising projects, the energy from the sea is still far from being a useful reality. WaveNet network created by the European Commission in 2000 and composed of academics, industries and research institutes from European countries, published a study explaining that the lack of public knowledge is one of the obstacles that hinder its development. The report detailed also some negative consequences that might arise in energy production, such as noise, risk of collision with ships, visual impact and possible changes in the structure of the water sediments. Consequently, the study highlighted the need for further research in order to make these technologies more competitive.
Environmental Education and Energetic Efficiency: Reports on Brazilian Projects in the Sake of Socio-Environmental Sustainability
Authors: Pereira Pinto Magda , Lessa Catalão Vera M.
Published: April 2010

The goal of this work is to describe the importance of environmental education in the energy conservation and energy efficiency process. Besides the various technical proposals aimed at minimizing energy waste, environmental education has been a primordial tool in the search of a more responsible character with respect to the environment. This article attempts at showing some reflections concerning the role environmental education plays in that process, as well as putting in evidence the educational actions of the National Program for Energy Conservation, with its emphases in diminishing the energy waste and pull towards its efficient use.
Interface Potential Modeling in a Finite Crystal
Authors: Cortés Ernesto E. , Torres Fernando M.
Published: April 2010

In this paper a model was proposed to calculate the interface potential of a non ideal finite crystal. Most of the research in this issue usually assume ideal conditions to work with infinite perfect crystals. The model includes a perturbative potential to consider an effect associated to finite size crystal and superficial atomic rearrangement. This effect is considered to be in a first order. The model was applied to graphite , as an example, mainly because of its theoretical interest for wastewater electrochemical treatment.
Hydrothermal Stability of Ordered Mesoporous Titanosilicate Materials Prepared at Room Temperature
Authors: Galacho Cristina , Ribeiro Carrott Manuela M.L. , Carrott Peter J.M. , Cansado Isabel P.P.
Published: April 2010

A study of hydrothermal stability, performed in boiling water under static conditions, of MCM-41 materials containing different titanium content, prepared by direct synthesis at ambient temperature and pressure, using tetraethoxysilane, titanium ethoxide and octadecyltrimethyl- ammonium bromide is presented. The behaviour is compared with pure silica grades prepared by a similar procedure. The samples were characterised by X-ray diffraction, adsorption of nitrogen at 77K and diffuse reflectance UV–Vis spectroscopy. It was found that the stability improves as the amount of titanium increases and that Ti-MCM-41 samples prepared with Si/Ti≤50 are significantly stable. After 12h in boiling water the pore size uniformity was practically maintained and only a small decrease in pore volume (5-9%), total surface area (2-7%) and mesopore width (3%) and a slight increase in pore wall thickness (3-6%) occurred. In contrast, some degradation of the MCM-41 structure for the pure silica and the lower Ti content (Si/Ti=100) samples was observed with the effect being less pronounced for the latter. The higher hydrothermal stability of titanium substituted samples is probably correlated with a higher degree of polymerisation of the pore walls and with the presence of extra framework titanium.
Ecological Design, an Objective in the Projects Engineering Area
Authors: Portela José M. , Pastor Andrés , Huerta Milagros M. , Otero Manuel , González Rafael E.
Published: April 2010

A part of this work takes place in a collaborative environment among students which have different knowledge and skills, and the rest is carried out in traditional classrooms to steer students towards the most appropriate solution. To obtain the best results it is necessary to apply the principles of respect for the environment where being more effective. This takes place in the design criteria and bases, especially to minimize the problem at source, recovery of materials, use of new materials, life cycles of products, etc.. (sustainability and respect for the environment). European universities are currently undergoing a convergence process to build and promote the European Higher Education Area and the guidelines for this process are being followed in our area. This teaching method focuses on the need to educate people so that they are capable of learning to learn and can continue to learn throughout their lifetimes.
Use of Centrifugal Pumps Operating as Turbines for Energy Recovery in Water Distribution Networks. Two Case Study
Authors: Pérez García José , Cortés Marco Antonio , Nevado Santos Simón
Published: April 2010

The main pipes in water distribution systems have, in many cases, an excess of static pressure. This excess of pressure is usually dissipated by means of intermediate reservoirs, pressure-reducing valves or any other device that produces the required energy loss with the aim to adjust the pressure level to the demand pattern of the system. This hydraulic energy can be used to directly drive a mechanical system or to generate electric power. In this type of recovery energy systems, the available hydraulic power is lower than 100 kW (micro-hydro). In this range, the utilization of conventional hydraulic turbines is not economically viable in short-medium time. In micro-hydropower applications the use of standard centrifugal pumps operated in reverse mode as hydraulic turbines (PAT) can be competitive. In this work, several prediction methods and algorithms suggested by different authors were analyzed and compared. Two case study, in the water system distribution of Murcia and Elche are also presented.