bluuebunny/crossref_metadata_2025 huggingface dataset:
Relationship between Infrared Radiant Properties in Different Waveband and Structure of Fe–Co–Ni–Cr Spinels
Authors: Guan Hao , Cheng Jun Hua , Jiao Bao Xiang , Zhang Xia
Published: June 2012

Fe-Co-Ni-Cr spinels have been prepared by conventional solid state sintering. The valence states and distribution of transition ions are be studied by the XPS analysis,thermodynamics analysis and crystalline field theory.The crystal structure and infrared radiant properties are studied by X-ray diffraction(XRD), Fourier transform infrared spectroscopy(FT-IR), IR radiation tester and band theory.With the change of Fe/Cr, the states of occupying are also change,leading to the information of different products of different lattice parameters and the variation of the spin state of Fe3+in octahedral sites，which causing the change of infrared radiation properities, and the action of different spin states of Fe3+and carriers has an important influence on infrared radiant properties in the 3～5μm band with increasing of the content of Fe.The optimized sample s3 exhibits the average emissitivity is 0.915 in the whole band,0.833 in the 3～5μm band and 0.948 in the 8～14μm band,respectively.
Fabrication and Properties of Ba(Zr0.63Ce0.27)Y0.1O3-δ/ZnO Electrolyte Materials
Authors: Guo Rui Song , Wu Li Jun , Gao Yan Ying , Deng Ya Ping , Jiang Hong
Published: June 2012

The perovskite-type Ba(Zr0.63Ce0.27)Y0.1O3-δ (BZCY) was synthesized by solid-state reaction. Sintering behavior and electrical conductivity of the electrolyte materials were improved through optimizing the content of ZnO as sintering aid. The obvious enhancement of density of sintered body was observed due to ZnO reacting with BZCY powder. Relative densities of the samples increased with ZnO content added. A conductivity of 9.27×10-3 S/cm tested in humid hydrogen at 800°C was obtained when the ZnO content was 2 mol%. A peak power density of 12.4 mW/cm2 was delivered based on a single fuel cell with electrolyte-supported configuration.
Preparation of Ultra–Fine La3NbO7 Powder by Solid State Reaction
Authors: Dai Ling , Xu Qiang , Zhu Shi Zhen , Liu Ling
Published: June 2012

As a new candidate material for the ceramic layer in thermal barrier coatings (TBCs) system, La3NbO7 was synthesized with La2O3 powder and Nb2O5 powder by solid state reaction. The stating powders with a mole ratio of La to Nb of 3:1 were mixed and then the mixture was calcined under the different temperatures(800°C, 1000°C, 1200°C) and dwell times(2h, 6h, 10h). The phase structure of the powder was observed by X–ray diffraction(XRD), and the microstructure of the sample was observed by scanning electron microscope(SEM). The effect of calcination temperature and dwell Time on the phase formation were examined. The results indicate that the La3NbO7 powder with single phase can be synthesized successfully at 1200°C for 10h in air, and the La3NbOsub>7 powders synthesized have an ultra-fine particle size of 0.5˜1µm with a granular particle shape. With the temperature increasing, LaNbO4/sub> was synthesized firstly and then La3NbO7 was synthesized with a mole ratio of La2O3 to LaNbO4 of 1:1.
Hydrothermal Synthesis of Li2MnSiO4 Powders as a Cathode Material for Lithium Ion Cells
Authors: Luo Shao Hua , Wang Ming , Zhu Xu , Geng Gui Hong
Published: June 2012

Li2MnSiO4 cathode materials were prepared by hydrothermal reaction at 150°C using LiOH, Si(OC2H5)4 and Mn(Ac)2.4H2O as raw materials followed by a low temperature heat annealing at 650°C. The samples were characterized by X-ray diffraction, scanning electron microscopy, FTIR. The powders electrochemical performance was investigated in terms of cycling behavior. Nanometer-sized flake crystalline particles of Li2MnSiO4 are obtained with some degree of agglomeration and little impure phases are detected after annealing. The charge capacity of the Li2MnSiO4 samples is 306 mAh/g (about 1.84 Li+ per unit formula extracted), and the discharge capacity is 114 mAh/g (about 0.68 Li+ per unit formula inserted) in the first cycle in the voltage range of 1.5–4.8 V under a rate of C⁄20. With increasing cycle number, the cell exhibits a well cycle performance with more than 95% coulombic efficiency and the maintenance of 61% of its discharge capacity after 50 cycles.
Photovoltaic Performance Optimization of Natural Trollius Sensitized Solar Cells
Authors: Yang Gui Jun , Wang Sen Rui , Lin Hong , Wang Gang , Zhang Yong Chang , Hao Feng , Chen Hui Yuan
Published: June 2012

Dye-sensitized solar cell is gradually becoming a strong competitor to Si-based solar cells, attracting much attention both from research and industry. Organic dyes used in dye-sensitized solar cells usually resemble dyes found in plants, fruits, and other natural products. In the present study, trollius pigment was extracted from a natural flower named trollius petals to serve as the sensitizer of the cells. UV-Vis absorption measurement revealed that the extracted pigment had a stronger absorbance under acid condition than that under basic condition. Devices were assembled with this trollius pigment, by systematically correlating the photovoltaic performance with the pH value of dye solution, film thickness and the sensitization time of the photoanode. The power conversion efficiency was increased by 37.9% when the pH of the dye solution was changed from alkaline (pH=9) to acidic (pH=4.3). The optimized efficiency of 0.254% was obtained when the film thickness was 13μm and the sensitization time was 3h under acidic condition.
Facile Fabrication of Open-Ended High Aspect-Ratio Anodic TiO2 Nanotube Films and their Applications
Authors: Liao Jian Jun , Lin Shi Wei , Pan Neng Qian , Cao Xian Kun , Li Jian Bao
Published: June 2012

In the present work, we demonstrated a facile process to prepare an open-ended high aspect-ratio TiO2 nanotube films through separating the anodic TNT array from the Ti substrate by a small reverse bias and opening the tube bottom by a chemical etching. The possible mechanisms of film detachment and pore opening processes have been briefly discussed. Such a process allows controlling the open-ended morphology by the straightforward chemical etching, which shows great potential in many applications, such as flow-through photocatalytic reactions, biofiltration, and diffusion controlling, and so on. An example using the open-ended TNT films is finally given as a flow-through photocatalytic reactor. The photocatalytic film has been shown to have multiple functions such as physical separation of contaminants, filtration, and decomposition of organic pollutants during diffusion.
The Effect of Acid Etching Process on Surface Morphology and Electrocatalytic Capability of RuO2-IrO2-TiO2/Ti Anode
Authors: Qu Dong , Hu Jin , Shen Li , Zhang Wei Jun , Wang Wei
Published: June 2012

Titanium substrate was etched by oxalic acid and hydrochloric acid respectively. Then the anodes of RuO2-IrO2-TiO2/Ti were prepared by Pechini method. The surface morphology of anodes was studied with SEM, EDX and XRD. The electrocatalytic capability of anodes was studied by polarization curve and cyclic voltammetry curve. The effect of Acid etching process on anode life was studied by accelerated life test. The results show that there was an obvious effect of acid etching on surface morphology of the anodes. The result indicates that the anode with hydrochloric acid etching have the better electrocatalytic capability and accelerated life.
Fabrication of Li2TiO3 Ceramic Pebbles by Gelcasting Method
Authors: Hong Ming , Zhang Ying Chun , Liu Yang Hong , Fu Bao Jian
Published: June 2012

Lithium titanate (Li2TiO3) ceramic pebbles are considered to be a candidate material of the tritium breeders for fusion reactor from the viewpoints of good tritium recovery, chemical stability and other excellent properties. In this study, fine grain and pure Li2TiO3 powders were prepared by solid-state method at 700°C using TiO2 and Li2CO3 as raw materials. Li2TiO3 pebbles were prepared by gel-casting method using acrylamide (AM) as organic monomer, N,N’-methylenebisacrylamide (MBAM) as cross-linker, ammonium citrate as dispersant, and isooctyl alcohol as defoamer. The effect of solid content, dispersant, pH and the ball milling time on the fluidity and dispersion of ceramics slurry were investigated, and the effects of sintering temperature and holding time were also discussed in present study. The sintered ceramic pebbles with diameter of 1.0 mm show a smooth surface, uniform grain size and perfect sphericity. The Li2TiO3 ceramic pebbles sintered at 1250°C for 8 hours had the highest density (> 90% of theoretical density) and crush strength.
Influence of Surface Composition of Silicon-Based Material on their Bioactivity
Authors: Niu Ya Ran , Zheng Xue Bin , Xie You Tao
Published: June 2012

Silicon coatings were prepared by vacuum plasma spraying (VPS) and air plasma spraying (APS) technologies. The samples were hydrothermally treated and then incubated in simulated body fluid (SBF) to evaluate their bioactivity and silicon wafer was used as control sample at the same time. The SBF test showed that a Ca-P layer was formed on the surface of silicon wafer and VPS-Si coating after immersion in SBF for certain time, indicating their improved bioactivity. Whereas no Ca-P layer was found on the surface of APS-Si coating. The results of X-ray photoelectron spectroscopy showed that the Si/O atomic ratio and chemical depth profiles of the silicon oxide films on the surface of silicon wafer, VPS-Si and APS-Si coatings were different. The results indicated that the bioactivity difference of silicon-based material resulted from the different composition of their surface. Hydrothermal treatment maybe a favorable method to improve the bioactivity of silicon-based material having silicon oxide of non-stoichiometric Si/O atomic ratio.
Preparing and Characterization of Hollow Ceramic Microspheres
Authors: Liu Liang , Xu Bao Cai
Published: June 2012

The hollow microsphere is a kind of new materials. It has a bright future for its excellent comprehensive performance. This article introduces a high-temperature synthetic technology on the basis of SHS to prepare new hollow ceramic microspheres. Reaction mechanism of hollow ceramic microspheres was studied. Results show that sphere, similar sphere and irregular powders constitute the spraying products. Sphere and similar sphere powders are hollow structure. Besides it also recommend the self-made equipments of collection that adopts three kinds of collections methods of static electricity, water and filter net. The total rate of collection raised above 80%.The effect is good. The hollow microsphere were analyzed through SEM and XRD, the hollow microsphere is regular spheroid or type spheroid.the size of the hollow microsphere is abort Similar. Its diameter is 20 μm or so. The equipments that experiment needs is simple, vivid craft and strong adaptability and respond that raw material and manufacturing circulate cost cheap.
Fabrication of Bi-2212 Films on Ag Substrate by Dip-Coating Method
Authors: Xu Jie , Li Ming Ya , Wang Xiao Yan
Published: June 2012

In this study, Bi2Sr2CaCu2Ox (Bi-2212) thick films on Ag substrate were fabricated using the dip-coating method. Firstly, the Bi-2212 powders were prepared by Sol-Gel process. Metal nitrates were used as starting materials and ethylenediaminetetracetic acid (EDTA) was used as chelating agent. Secondly, the resulting powders were used as solute, and polyvinyl butyral (PVB) was used as solvent to prepare suspension via stirring and ultrasonic vibration. Then the suspension was dip-coated on Ag substrate. After heat treatments, the phase compositions of the samples were characterized using the XRD. The microstructure was observed using SEM. Experimental results show that the sintering temperature strongly influence the phase formation of Bi–2212.
Synthesis and Surface Characterization of a Silica White Prepared from High Si:Al Fine Powder
Authors: Chen Nan Chun , Zhao Cheng Ju , Wang Wei , Li Meng Ying
Published: June 2012

This paper describes the synthesis and surface characterization of a new silica white prepared from a high Si:Al fine powder by using the sulfuric acid precipitation method. In the beginning, water and alkali are added to the sieved high Si:Al fine powder. The mixed liquid is then heated until it is boiling and left alone at the same temperature for 2.5 hours before it is filtrated. Applying liquid NaCl (20%) to the filtrated solution before it is heated to 80°C. Applying certain amount of surfactant and H2SO4 (20%) while maintaining the temperature at 80°C for 3 hours before it is washed, precipitated, filtrated, and dried to produce the final product of silica white. Examinations with XRD and IR show that the silica white is amorphous silicon. It has a PH value of 7-7.5 determined by aqueous suspension method, a white index of 96% and above, a volume average particle diameter of 4.6 - 7.1 µm, a specific surface area of 95.5-103.1 m2/g, an oil absorption rate of 4.34-4.87 ml/g, and a LOI (loss on ignition) of 5.12% at 1000°C. The synthesized silica white has a satisfying uniformity of particle sizes, meeting standard of HG/T 3061-1999.
Effect of Additive Silicon Powder on Physical Property of Cold Ramming Paste for Aluminum Electrolysis
Authors: Yu Xiao Hua , Fang Ning , Li Yong Gang , Xie Gang , Tian Lin
Published: June 2012

The cold ramming paste for aluminum electrolysis has been studied using electrically calcined anthracite as aggregate, medium temperature pitch and anthracene oil as binder, metallic silicon powder as additive in the paper. The effects of addition of silicon on volume density, compressive strength, electrical resistivity, shrinkage value have been studied. The results show that: volume density, compressive strength of cold ramming paste are increased firstly and then decreased with the addition of silicon increasing, and electrical resistivity, shrinkage value are decreased firstly and then increased with the addition of silicon increasing. So when the addition of silicon is 3%, the physical properties are preferable.
The Screening of Modifying Alumina Used in Automotive Catalyst
Authors: Zhang Wei Jun , Hu Jin , He Xiao Kun , Zhao Na , Duan Yun Biao , Shen Li
Published: June 2012

As automotive catalyst support, alumina thermal stability is a importent problem of catalyst. This paper focus on the need for influence on calcination temperature to the pore structure and phase of modified alumina. Screen better modified alumina raw materials by characterization and analysis of the S.A, T.P.V and A.P.D.
Effect of Calcination Temperature on Phase Transformation and Microstructure of Al2O3/GdAlO3 Compound Powder Prepared by Co-Precipitation Method
Authors: Sun Shuai , Xu Qiang
Published: June 2012

A Coprecipitation Method Was Applied to Synthesize Al2O3/GdAlO3 Compound Powder, Using Ammonia as the Precipitator. Gadolinium Oxide and Aluminium Nitrate Were Used as the Raw Materials with the Eutectic Ratio( 77 mol% Al 3+ – 23 mol% Gd 3+ ). the Precursor Was Calcined at Different Temperatures from 1200 to 1600 °C. the Phase Identifications at Different Temperatures Were Characterized by X-ray Diffractometry (XRD). the Growth Morphology of Particles Were Investigated Using Field Emission Electro Microscopy (FE-SEM). the Results Reveal that GdAlO3 Crystallized Earlier than α-Al2O3. the Diffraction Peaks of α-Al2O3 Phase Were Observed after Calcination at 1300°C for 1 H. Metastable Phase Gd3Al5O12 Underwent Complete Decomposition at 1600°C for 1 H. Gadolinium Aluminate and α-Al2O3 Showed Different Growth Mechanism during the Calcination Process. the Average Grain Size of the Calcined Powder Increased from ~40 to ~900 Nm as the Calcination Temperature Increased from 1200 to 1600 °C.
Dielectric Properties of Silica Fiber Reinforced Silica Composites
Authors: Wang Chong Hai , Wei Qi Hong , Wang Hong Sheng , Li Ling , Luan Qiang , Liao Rong
Published: June 2012

Silica fibers are widely used in superhigh velocity missile’s antenna housing and windows.The effects of heat treatment temperatures, heat treatment atmosphere，dampproof process and impurities contents on the dielectric properties of silica fiber reinforced silica composites were sdutied.Electric network apparatus was used to test the dieletric constants and dielectric loss of silica fiber reinforced silica composites treated at different conditions.The results indicate that silica fiber reinforced silica composites must have dampproof process.The dielectric properties of silica fiber reinforced silica composites was better with little carbon.The dielectric constant was about 3,and the dielectric loss was less than 5×10-3.The minimum transmission coefficient was 68.2%, the average transmission coefficient was 78.5% ~ 86.2%, which showed the radome had good wave penetrating performance.
Fabrication and Properties of Mullite Fiber-Reinforced Porous Mullite Ceramics
Authors: Lang Ying , Wang Chang An , Zhou Jun
Published: June 2012

Porous mullite ceramics reinforced by mullite fiber have been prepared by vacuum filtering with MgO as sintering aid and starch as pore-forming agent. The influence of different sintering temperature and mullite fiber content on porosity and strength of porous mullite ceramics was investigated. The results showed that the compressive strength of the mullite ceramics increased with increasing sintering temperature. With the increase of mullite fiber content, the compressive strength of porous mullite ceramics appeared to increase at first and then decrease. And the peaking strength could reach 211MPa with 36.8% porosity when 7 vol% mullite fiber was added and sintering temperature of 1500 oC was adopted.
Preparation of Rare-Earth Doped Zirconia Nanoparticles via Supercritical Hydrothermal Method for Luminescence Properties
Authors: Hakuta Yukiya , Sue Kiwamu , Takebayashi Yoshihiro , Yoda Satoshi , Furuya Takeshi , Takashima Hiroshi
Published: June 2012

We report preparation of Tb3+ or Eu3+ doped zirconia nanoparticles by sub- and supercritical hydrothermal reaction and luminescence properties. Experiments were performed by a flow-type hydrothermal reaction system. We investigated the effect of the reaction temperature on crystal structure, particle size and photo-, electro-luminescence properties. Reaction temperature was varied in the ranges of 150 to 400 C and reaction pressure was fixed to 30MPa. Characteristics of the products were performed by XRD, TEM, SEM-EDS and PL, EL measurements. The product transformed from amorphous zirconium hydroxide to tetragonal ZrO2 with an increase in the reaction temperature, regardless of the doped ion species. The ZrO2:Eu particles obtained at 400C were spherical with around 5 nm in diameter. ZrO2:Eu nanoparticles obtained under supercritical water condision showed typical photoluminescence spectra of f-f transition of Eu3+; however ZrO2:Tb nanoparticle obtained under the same condition showed no photoluminescence. Furthermore, the ZrO2:Eu nanoparticles obtained at 400 C showed high electroluminescence properties at electric field of 350V and 1kHz.
Fabrication and Properties of Porous Anorthite⁄Mullite Ceramics
Authors: Lin Ya Mei , Li Cui Wei , Yang Feng Kun , Wang Chang An
Published: June 2012

Porous anorthite/mullite composite ceramics with different mullite content were fabricated by foam-gelcasting, using CaCO3, SiO2, α-Al2O3as raw material for anorthite phase and mullite powder for mullite phase. Effects of mullite powder content on bulk density, porosity, compressive strength and thermal conductivity of the porous composite ceramics were researched. It has been shown that mullite powder content has great effect on microstructure and properties of the porous anorthite⁄mullite composite ceramics. The open porosity of the prepared porous anorthite⁄mullite composite ceramics is in the range of 58.7 %~77.5 %, the compressive strength is between 4.2 and 30.9 MPa, and the thermal conductivity is in the range of 0.18 ~1.47 W⁄(m·K).
Colorimetry Study on Red Tourmaline Color Genesis
Authors: Li Yan , Guo Ying
Published: June 2012

In this paper, the colorimetry characteristics of ten red tourmaline samples were studied through the visible light spectrometer Color I5 of X-rite company of the United States. In order to give a quantitative description of the color of red tourmalines, the chromaticity index of the samples was measured, and the red tourmaline color parameters with possible principle and technology for evaluation were obtained, including chroma coordinates, main wavelength, chroma, brightness, curves of reflection rate and chroma figures. Combining with the electron probe microanalysis and the chemical analysis, the relationship between the content change of color-caused ions and the color parameters was discussed by analyzing the existing states and content of color-caused ions Mn2+(ion), Cr3+(ion) and Fe2+(ion).
Synthesize Ti3SiC2 and Ti3SiC2-Diamond Composites at High Pressure and High Temperature
Authors: Zhou Ai Guo , Li Liang , Su Tai Chao , Li Shang Sheng
Published: June 2012

Ti3SiC2, a ternary carbide, was proposed at this paper to use as the binder of polycrystalline diamonds to overcome the weaknesses of traditional metal binders and ceramic binders. Ti3SiC2was first reported to be in-situ synthesized under high pressure (4GPa) and at high temperature (1400°C) (HPHT) from the mixtures of Ti, Si and graphite powders or the mixture of Ti, SiC and graphite powders. Ti3SiC2-damond composites were also made at HPHT from the previous mixtures and diamond particles. TiCx, Ti5Si3Cxand TiSi2were main impurities and/or intermediate products of Ti3SiC2samples synthesized at HPHT. Ti3SiC2content increased as synthesized time increased from 10 min to 60 min. For as-synthesized composites, diamond particles were evenly distributed in matrix. The diamond particles are bonded well with the matrix by three types of interface.
Effect of High-Energy Ball Milling of ZrB2 Powder on the Microstructure and Mechanical Properties of ZrB2-SiC Ceramics
Authors: Guo Qi Long , Li Jun Guo , Shen Qiang , Zhang Lian Meng
Published: June 2012

The sinterability of ZrB2-20vol.% SiC ceramics by high-energy ball milling as well as introduction of Zr and Al as sintering additives. Densification process and microstructure of ZrB2-SiC ceramics were investigated. After high-energy ball milling, the average particle size decreased to about 500 nm-2 μm, and ZrB2-SiC powder can be sintered to 98.92% theoretical density at 1800 °C, but a trace of amount of oxidation (ZrO2) were detected in sintered sample. Introduction of Zr, Al and C combined with high-energy ball milling enhanced the densiﬁcation of ZrB2-SiC ceramics and reduced the particle sizes, and the relative density of obtained ceramic reached up to 99.49% at 1800 °C. The additions of Zr, Al and C can remove the oxide impurities of the surface of ZrB2 particles and form a reaction between oxide impurities. The fracture toughness increased of the 40% when ZrB2 powders were milled by high-energy ball milling, and increased to 4.77±0.18 MPa•m1/2. However, the attrition-milled composites had lower hardness and Young’s modulus, which was attributed to the presence of a second phase in the grain boundaries.
Study on ZrB2-SiC Prepared by Field Assisted Sintering
Authors: Wang Wei Jun , Zhu Shi Zhen , Yan Zhen Yu , Xu Qiang
Published: June 2012

Zirconium diboride and silicon carbide are thought to have a low intrinsic sinterability due to their strong covalent bonds, low bulk and grain boundary diffusivities. ZrB2-SiC ceramic composites were prepared by a field assisted pressureless sintering process in the present work. The densification behavior and the effect of sintering temperature on microstructure and properties of sintered samples were studied. Pellets were in-situ formed by dry uniaxial pressing in the graphite die at a pressure of 50MPa for 3min and then sintered at a sintering temperature ranged from 1650 °C to 1950 °C with fixed heating rate and holding time. The current, voltage, temperature and displacement data were all collected by the real-time acquisition system. The bulk densities were determined by Archimedes method and the microstructure of samples was characterized by SEM. The onset of some measurable shrinkage of the green body was recorded at around 1400 °C regardless of the sintering temperature and significant shrinkage took place at higher temperature of around 1600 °C. For the sample sintered at 1950 °C, no shrinkage occurred after ~2min holding time. The relative density increased significantly with increasing temperatures and samples could be densified to a relative density of more than 99% at 1950 °C by the field assisted sintering process without obvious grain growth.
Preparation of Cf/SiC Composites by Chemical Liquid-Vapor Deposition Process
Authors: Mei Min , He Xin Bo , Qu Xuan Hui , Hu Hai Feng , Zhang Yu Di , Chen Si An
Published: June 2012

The conversion of the liquid polycabosilane (LPCS) into silicon carbide was investigated by IR, XRD, which indicated the feasibility of the transition from LPCS to SiC ceramics above 900°C. The FTIR spectra and XRD Pattern of the Cf/SiC composites show that the matrix deposited at 1200°C has silicon carbide structure with the crystallite size of β-SiC phase of about 41 nm, while the SiC phase is amorphous at 900°C. The carbon fiber reinforced silicon carbide composites (Cf/SiC) were hereby prepared at 900°C and 1200°C, through chemical liquid-vapor deposition (CLVD) process using LPCS as precursor. Flexural strength of 224 MPa for Cf/SiC specimen with density of 1.81g·cm-3was obtained after being prepared at 1200°C for 30 minutes. The load-deflection curve has shown that the fracture behavior of the Cf/SiC composites is a typical non-brittleness. The results indicate that the CLVD process has a great advantage and prospect to prepare Cf/SiC composites in future.
First Principles Investigation of Electronic Structure, Chemical Bonding, Elastic and Optical Properties of Novel Rhenium Nitrides
Authors: Xia Qing Lin , Pan Liu Xian , Peng Yuan Dong , Li Li Ya , Wang Hong Zhong , Bao Rui , Yi Jian Hong
Published: June 2012

we investigate the electronic structure, chemical bonding, optical and elastic properties of the novel rhenium nitrides, hexagonal phase re3n and re2n by using density-functional theory (dft) within generalized gradient approximation (gga). the calculated equilibrium lattice constants of both re3n and re2n are in reasonable agreement with the experimental results. the band structure along the higher symmetry axes in the Brillouin zone, the density of states (dos) and the partial density of states (pdos) are presented. the calculated energy band structures and dos show that re3n and re2n are metal compounds. The dos and pdos show that the dos at the fermi level (ef) is located at the bottom of a valley and originate mainly from the 5d electrons of re. population analyses suggest that the chemical bonding in re3n and re2n has predominantly covalent character with mixed covalent and ionic characteristics. the dielectric function, reflectivity, absorption coefficient, refractive index, electron energy-loss function and optical conductivity are presented in an energy range for discussing the optical properties of re3n and re2n. basic mechanical properties, such as elastic constants cij, bulk modulus b and shear modulus g are calculated. The young’s modulus e, poisson's ratio ν and bh/gh are also predicted. results conclude that the hexagonal phase re3n and re2n are mechanical stable and behaves in a ductile manner. polycrystalline elastic anisotropy is also derived from polycrystalline bulk modulus b and shear modulus g.
Carbon Fiber Reinforced Phosphate Porous Ceramic Composites
Authors: Zhai Ping , Duan Xiao Feng , Chen Da Qian , Wang Chong Hai , Gao Fang , Dong Bo
Published: June 2012

Fiber porous ceramics are the excellent candidates for a variety of applications, and thus, their research is a hotspot in recent years. In this study, carbon fiber reinforced phosphate porous ceramics composites were prepared by acupuncture and in-situ solidification vacuum-assisted liquid-phase infiltration method. The tensile strength of composite was tested by universal testing machine, the microstructures of the specimen were observed by scanning electron microscopy while the thermal analysis was detected by Thermo Gravimetric Analyzer. The results show that the carbon fiber reinforced phosphate porous ceramics composites which is prepared by the technology showed above have a pore rate of 63.7%.The tensile strength reached 50.2MPa with an average pore size of at most 50μm.It also has good thermal shock resistance.
Study on Thermal Insulating Behavior of Silica Glass Fiber/Aluminum Phosphate Composite
Authors: Wang Chun Peng , Liu Hai Lin , Huo Yan Li , Tang Jie , Chen Yu Feng
Published: June 2012

Thermal insulating behavior of silica glass fiber / aluminum phosphate composite was studied. The composite samples were prepared through hot-pressing of stacked pieces of plain woven fabric made from silica glass fiber with aluminum phosphate paste placed between the pieces of the fabric. When the mixture ratio of Al2O3:AlPO4:H2O was 10:2.88:2.88 in aluminum phosphate paste, the paste was suitable for preparing the composite. The thermal insulation of the composite was excellent, when volume content of fiber in the composite was from 27.6% to 33.57% and the densities of the composite were from 1.82 g/cm3 to 1.90 g/cm3. Heating test with oxyacetylene flame showed that when one face of the composite was heated up and hold at temperature of 1800°C for 10 mins, the temperature of the opposite face remained at 765°C to 775°C. The composite was not damaged during the above testing. As it was observed with microscope, there were little changes in microstructure of the composite after heat test.
Experimental Study and Numerical Simulation on Fatigue Crack Growth Behavior of GH4133B Superalloy
Authors: Zhao Rong Guo , Li Xiu Juan , Jiang Yong Zhou , Luo Xi Yan , Li Jun Fei , Li Hong Chao , Tan Dun Hou
Published: June 2012

The fatigue crack growth tests for nickel-based GH4133B superalloy used in turbine disk of a type of aero-engine are carried out at room temperature. The stress intensity factor ranges and the fatigue crack growth rates at various stress ratios are measured, and the corresponding threshold stress intensity factor ranges are determined. Using the Paris formula, the experiment data of fatigue crack growth are analyzed. It is shown that the fatigue crack growth rate increasing with increasing stress intensity factor range and stress ratio, and a modified Paris formula considering threshold stress intensity factor range can describe the fatigue crack growth behavior precisely. The fracture surface morphologies are investigated using a scanning electron microscope. It is shown that in the crack initiation region, steady growth region and rapid growth region, the fracture surface exhibits a cleavage fracture mode, fatigue striations and an intergranular fracture mode, respectively. Finally, the von Mises stresses and stress intensity factors at the crack tip of specimen of GH4133B superalloy at various external loads and crack lengths are simulated using the finite element method, and the threshold stress intensity factors under different maximal external loads at a certain crack length are calculated. The comparison between test and simulation indicates that the stress intensity factors at the crack tip calculated by the finite element method agree well with experimental data.
The Electromagnetic Properties of Different Urchinlike Ni Nanostructures
Authors: Qi Hai Ping , Wan Jun Xi , Cao Hai Lin , Huang Yu Dong
Published: June 2012

Urchinlike Ni particles with different spines were synthesized. The microstructures and morphologies of the resulting materials were investigated by X-ray diffraction and scanning electron microscopy. And the electromagnetic parameters of these urchinlike Ni were measured with vector network analyzer at 2-18 GHz frequency. The results indicate that the electromagnetic parameters are affected by morphologies of materials. The long urchin spines will lead to larger permittivity.
Effects of Ambient Pressure on the Structural and Magnetic Properties of Bismuth Ferrite Nanoparticles Prepared by Pulsed Laser Deposition (PLD)
Authors: Yao Ying Bang , Zhang Bei , Chen Long , Yang Yang
Published: June 2012

Nanoparticles of bismuth ferrite (BiFeO3) were fabricated by high-pressure pulsed laser deposition method (PLD) on Pt-coated Si substrates. Effects of the ambient oxygen pressure during deposition (from 1 Torr to 15 Torr) were studied with respect to the microstructures and magnetic properties of the samples. It was found that as the pressure is higher than 5 Torr isolated nanoparticles are formed and the size of these nanoparticles decreases with the deposition pressure. All the nanoparticles exhibit ferromagnetic behavior and the magnetic coercive filed decreases with the particle size.
CFD Analysis on the Flow Field of Minimum Quantity Lubrication during External Thread Turning
Authors: Chen Ming , Jiang Li , Shi Bo Wen , Liu Zhi Qiang , An Qing Long
Published: June 2012

Minimum quantity lubrication (MQL) is a new cooling technology used in machining process, which is friendly to environment and lower cost. This paper applied computational fluid dynamics (CFD) to analyze flow field of MQL in thread turning. Comprehensively applying droplet breakup method and capillary method, flow field of MQL in cutting zone were analyzed in detail. The results showed that oil mist could enter into cutting zone from sides of chip. And two vortexes existed around cutting zone which could reduce cutting temperature by accelerating heat exchange. Furthermore, flow rate of compressed air had great influence on velocity and diameter of droplets, velocity and pressure distribution of flow field. The effects of different flow rates indicated the larger flow rate was benefit for entering into cutting zone of oil mist.
Turbine Blade Distortion Analysis during Spiral NC Milling Based on FEM
Authors: Wan Yi , Wu Zhi Xin , Wang Yu , Liu Zhan Qiang
Published: June 2012

Turbine blade plays an important role in aero engine and power generation equipment. As thin-walled and free-form surface component, deflection in spiral milling of turbine blade is common, which result in bad dimensional precision. In this paper, a five-axis milling experiment was firstly conducted to get the cutting force components. Then, deflections were studied at different positions. The results show that compensation can be made based on the FEM analysis.
Experimental Study on Turning of Titanium Matrix Composites with PCD Tools
Authors: Huan Hai Xiang , Xu Jiu Hua , Fu Yu Can , Su Hong Hua , Bian Wei Liang , Zhang Yu
Published: June 2012

Titanium Matrix Composites (TMCs) parts usually requires high mechanical performance. The good workpiece surface quality and long tool life is the two target of finishing machining. In this paper, finishing turning tests are performed to investigate the workpiece surface roughness and tool life of machining TMCs with Polycrystalline Diamond (PCD) tools at the cutting speed range 60m/min to 120m/min. The results show that the workpiece surface roughness is obtained range Ra 0.44 to Ra 0.53m. tool life reaches about 10.6min, 7.9min, 7min and 5.5min at the cutting speed of 60m/min, 80m/min, 100m/min and 120m/min, respectively.
Modal Experiment and Analysis of HSK Tool-Holder and Thin-Disk Cutter
Authors: Song Wei , Yang Lei , Wang Gui Cheng , Shen Chun Gen
Published: June 2012

On the basis of modal analysis theory, a free modal test and a work modal test of the HSK tool holder and thin-disk cutters with the vibration measuring method were carried out. The modal parameters such as inherent frequency, damping ratio and modal shapes were gained. These modal parameters were compared with modal parameters, which were gained with the finite element method. The results verified whether the construction of the finite element modal was reasonable or not, and provided technical help for exploring the dynamic characteristics and structural optimization of HSK tool system, making the full use of HSK tool holder in high- speed machining.
The Heat Performance Analysis of HSK Shrink Toolholder
Authors: Chen Jian , Wang Gui Cheng , Song Wei , Liu Gang
Published: June 2012

The principle of the HSK shrink toolholder is expanding with heat and contracting with cold. The heat performance of HSK is analyzed. Firstly, the induction heating performance is studied by using electromagnetism-thermal-structure FEA in ANSYS software and experiment, the optimal temperature of HSK shrink toolholder is got. Secondly, thermal fatigue and calculation of the fatigue life is analyzed by using thermal-stress in ANSYS software and Coffin-Manson formula. The loads applied on the FEA model are temperature during the cycle of heating and cooling.
Sustainable High Speed Dry Cutting of Magnesium Alloys
Authors: Guo Yue Bin , Liu Zhan Qiang
Published: June 2012

Magnesium (Mg) components can significantly reduce energy use due to their low densities compared to the majority alloys. Mg alloys are often machined to fit individual cases. However, process mechanics by high-speed dry cutting of Mg alloys are poorly understood. This study focuses on machining ability of biomedical magnesium-calcium (Mg-Ca) alloys. First, it presents a modeling approach of mechanical behavior of Mg-Ca0.8 (wt %) alloy under cutting regimes using the internal state variable (ISV) plasticity model. Then, the ISV plasticity model is implemented to simulate high speed dry cutting of Mg-Ca0.8 alloy by finite element method. Last, machining performance in the context of sustainability is discussed. Excellent surface finish can be achieved in the range of high cutting speeds. Continuous chip formation predicted by the finite element simulation is verified by high speed dry cutting of Mg-Ca0.8 using polycrystalline diamond (PCD) inserts. Chip ignition as the most hazardous aspect in machining Mg alloys does not occur for in high-speed dry cutting with sharp PCD tools. The predicted temperature distribution well explains the reason for the absence of chip ignition in high speed dry cutting of Mg-Ca0.8 alloy. A mechanism of built-up layer (BUL) formation is proposed.
Experimental Study on Exit Edge Defects in Two Dimension Cutting of SiCp/Al Composites
Authors: Zou De Jin , Huang Shu Tao , Zhou Li , Xu Li Fu , Hou Ning , Wang Jing Lei
Published: June 2012

In this paper, the influence of the tool rake angle, cutting depth and cutting speed on exit edge defect sizes are discussed by the two dimension cutting experiment of SiCp/Al composites. The sizes are measured by using the Keyence VHX-1000C type super preview 3D microscopy. The results indicate that exit edge defect sizes are influenced greatly by tool rake angle and cutting depth, and are influenced slightly by the cutting speed. The edge defect sizes have an overall downward trend when the tool rake angle is smaller than 5°, and have an apparent upward trend when the tool rake angle (γ0) is 10°.The length (L), height (H) of exit edge defects and the negative shear angle increase with increasing of the cutting depth.
Investigation of Trochoidal Milling Nickel-Based Superalloy
Authors: Wu Bao Hai , Zheng Cheng Yu , Luo Ming , He Xiao Dong
Published: June 2012

Nickel-based superalloy is a relatively new class of materials that exhibit high mechanical strength, ductility, creep resistance at high operating temperatures and stress levels. It is widely used in aero engine parts such as blade and blisk. Due to its high hardness and high strength at high temperature, it’s difficult to machine nickel-based alloy. In order to reduce tool wear, trochoidal milling strategy is studied in this paper. With trochoidal tool path strategy, tool load can be reduced and the tool has enough time to be cooled under high cutting temperature. Tool immersion angle in trochoidal milling is smaller than slot milling, thus the tool load can be reduced. Experiment results show that tool flank wear with normal slot milling is about four times larger than that with trochoidal milling. Trochoidal tool path strategy can be further developed for rough milling of compressor blades or rough milling hub of blisks.
ZTA Ceramics Tensile Fracture Test Analysis under Ultrasonic Vibration Based on Nonlocal Theory
Authors: Zhao Bo , Chen Fan , Tong Jing Lin
Published: June 2012

The nonlocal theory was introduced to establish the nonlocal constitutive model and analyze the effect of ultrasonic on the tensile strength and fracture surface microstructure. ZTA ceramics tensile fracture experimental results show that the tensile stress obviously reduces and the fracture changes under ultrasonic vibration. The experimental results are coincided with theoretical analyses.
Cutting Performance and Tool Failure in Intermittent Turning Processes of an Al2O3-Based Micro-Nano-Composite Ceramic Tool
Authors: Zhou Yong Hui , Zhao Jun , Cui Xiao Bin
Published: June 2012

An Al2O3-based micro-nano-composite ceramic cutting tool material reinforced with (W, Ti)C micro-particles and Al2O3 micro-nano-particles was fabricated by using hot-pressing technique, the composite was denoted as AWT. The cutting performance, failure modes and mechanisms of the AWT micro-nano-composite ceramic tool were investigated via intermittent turning of hardened AISI 1045 steel (44~48 HRC) in comparison with those of an Al2O3/(W, Ti)C micro-composite ceramic tool SG-4 and a cemented carbide tool YS8. Worn and fractured surfaces of the cutting tools were characterized by scanning electron microscopy (SEM). The results of intermittent turning revealed that shock resistance of the AWT ceramic tool was higher than that of the SG-4 and YS8 tools at all the tested cutting speeds. The excellent shock resistance of the AWT composite ceramic tool was attributed to its synergistic strengthening/toughening mechanisms induced by the (W, Ti)C micro-particles and Al2O3 nano-particles.
Hidden Memories: Frontline Memory T Cells and Early Pathogen Interception
Authors: Masopust David , Picker Louis J.
Published: June 2012

Immunologic memory reflects the ability of a host to more effectively respond to a re-encounter with a particular pathogen than the first encounter, and when a vaccine mimics the first encounter, comprises the basis of vaccine efficacy. For T cells, memory is often equated with the anamnestic response, the ability of secondary lymphoid tissue-based (central) memory T cells to respond to pathogen exposure with a more rapid and higher magnitude production and infection-site delivery of pathogen-specific effector cells than observed in naive hosts. However, increasing evidence supports a fundamentally different kind of T cell memory in which differentiated, long-lived effector memory T cells, prepositioned in sites of potential pathogen invasion or rapidly mobilized to such sites from blood and marginated pools, intercept and potentially control/eliminate pathogen within hours of infection. In this article, we review the evidence for this “hidden” T cell memory and its implication for vaccine development.
Treatment of vitiligo vulgaris with the combination therapy of topical steroid and vitamin D3 compound
Authors: Konishi Yoko , Yamanaka Keiichi , Mizutani Hitoshi
Published: June 2012

We reported here two cases of vitiligo vulgaris successfully treated with the combination therapy of topical steroid and vitamin D3 compound and currently maintained by vitamin D3 analog without any adverse effects: skin atrophy, striae or telangiectasia on the exposed areas. The best-known mechanism of topical vitamin D3 analog is the enhancement of keratinocytes differentiation and anti-proliferative effects. Vitamin D3 analog is also reported to suppress T-cell mediated immunity, T-cell skin recruitment, and skin infiltration via down-regulating cutaneous lymphocyte antigen expression. Furthermore, vitamin D3 compounds are known to influence melanocyte maturation and differentiation and also to up-regulate melanogenesis. Autoreactive lymphocytes against melanocytes are one of the causes. Topical vitamin D3 analog may control vitiligo itself, however stronger immunosuppressive effects of topical corticosteroid may contribute to rapid re-pigmentation suppressing auto-reactive lymphocytes. The topical combination therapy is a simple, effective and safe option for vitiligo vulgaris in sun-exposed areas.
Clinical evaluation of general anaesthesia in pigeons using a combination of ketamine and diazepam
Authors: Azizpour Aidin , Hassani Yashar
Published: June 2012

This study was undertaken to investigate the clinical effects of ketamine, diazepam and a ketamine and diazepam combination in the general anaesthesia of pigeons. Thirty-two pigeons of both sexes with body weights ranging from 280 g to 300 g were allocated randomly to four groups comprising eight birds each. Group D received a 0.5 mL mixture of diazepam (0.2 mg/kg) and normal saline, group K a 0.5 mL mixture of ketamine 5% (30 mg/kg) and normal saline, group D, group KD a 0.5 mL mixture of ketamine 5% (10 mg/kg), diazepam (0.2 mg/kg) and normal saline, whilst group C (control) received 0.5 mL of normal saline only. Each mixture was administered intramuscularly.Under standard operating room conditions, general anaesthesia was not observed in group C (normal saline alone). In group D, sedation and muscle relaxation without complete loss of consciousness was observed. Induction time of anaesthesia in group KD was significantly quicker than group K (p 0.05). Duration of anaesthesia in group KD was significantly longer than group K (p 0.05). Recovery took longer in group KD in comparison with group K, but the difference was not statistically significant (p 0.05). The birds in group KD were calm and sedated, with good muscle relaxation, whilst in group K the birds were excited and showed a drop in body temperature.According to the results of this study, the combination of low dose ketamine hydrochloride (HCL) and diazepam overcame the adverse effects of ketamine alone. This combination produced a more rapid induction of anaesthesia, as well as an increase in anaesthesia duration, with good muscle relaxation and a smooth and slow recovery. Use of a combination of ketamine HCL given at 10 mg/kg and diazepam given at 0.2 mg/kg for anaesthesia in pigeons is therefore recommended.
FNAC in the diagnosis of lymph node malignancies: A simple and sensitive tool
Authors: Wilkinson Anne R , Mahore Sadhana D , Maimoon Sabiha A
Published: June 2012

Context: Fine needle aspiration cytology (FNAC) of the lymph node is a simple diagnostic tool to diagnose suspected and unsuspected secondary and primary lymph node malignancy. Aim: To study the utility of FNAC in the diagnosis of clinically suspected and unsuspected lymph node malignancy. Design: A cross-sectional hospital based study on 50 patients diagnosed to have primary or secondary lymph node malignancy by cytology, and confirmed by histopathology. Materials and Methods: Lymph node aspirate smears reported as malignant were studied and the findings were correlated with histopathology. Clinical and radiological data were also noted. Statistical Analysis: The data were tabulated as per the involvement of the various lymph node groups and the types of secondary and primary lymph node malignancies involved. Results: 45 cases of metastatic malignancy and five cases of lymphomas were diagnosed by FNAC of lymph nodes. Histopathological correlation was available in all cases. Malignancy was clinically unsuspected in nine cases (18%). Conclusion: FNAC of lymph nodes is a very useful, simple and sometimes the only tool in the diagnosis of lymph node malignancies.