bluuebunny/crossref_metadata_2025 huggingface dataset:
XRD and Morphologic Analysis of α-Cristobalite Produced from Silica Mine Waste under Lower Calcination Temperature
Authors: Chen Nan Chun , Wu Wen Hui , Li Zhao , Deng Ai Ping
Published: June 2011

This paper describes a new method developed to produce α-cristobalite from silica mine waste under lower-than-usual temperature, and presents XRD (X-ray diffraction) and morphologic analysis of the produced α-cristobalite. In the method, silica mine waste with average grain volume of 87.3 µm is firstly refined and processed to have a whiteness of 83.5 and a chemical composition of SiO2 of 99.87%, Al2O3 of 0.15%, and Fe2O3 of 0.015% (by weight), before calcinating the processed samples. The experiment results demonstrate that, under oxidizing condition, addition of mineralizer and occurrence of iron oxides as impurity in the mine waste, facilitate lowering both crystallization temperature of amorphous silica and calcination temperature of cristobalite from 1470°C to 1100-1250°C, shortening formation time of cristobalite to 3 hours, raising transformation rate up to 93.7%-99.7%, and increasing whiteness up to 92.3%-96.7%.
Effect of Annealing on Structural and Optical Properties of Zr Doped ZnO Film Grown by RF Magnetic Sputtering
Authors: Wang Jun , Zhang C.Y. , Wu Zhi Guo , Yan Peng Xun
Published: June 2011

Zinc oxide (ZnO) and Zirconium (Zr) doped ZnO nano films have been successfully fabricated by radio frequency (RF) magnetic sputtering. The crystal structure and morphology were investigated by X-ray Diffraction (XRD), Field Emission-Scanning Electron Microscope (FE-SEM) and Transmission Electron Microscope (TEM). As the doped Zr content increases, ZnO nano films show various morphologies. The optical band gap of pure ZnO films increases from 3.27 eV to 3.53 eV with Zr concentration increasing to 9.66 at.%. After annealing, the polycrystalline structure of ZnO changes a little and the energy gap decreases. In addition, the clean and lower doped ZnO films show much lower transmittance.
Mechanical Properties and Strengthening Mechanisms of In Situ (TiB+TiC)/Ti-1100 Composite at Elevated Temperature
Authors: Ma Feng Cang , Liu Ping , Li Wei , Liu Xin Kuan , Chen Xiao Hong , Zhang Di
Published: June 2011

In this paper, Ti-1100 composites reinforced with TiB+TiC ceramic particles were fabricated using in situ technologies. Mechanical properties of the composites with different volume fractions of TiB and TiC reinforcements were evaluated by tensile tests at 873K. The breakage of TiB was observed during the failure process of the composite. Strengthening efficiencies of the reinforcements for different composites were calculated. The strengthening mechanisms in this composite during tensile tests were discussed. It was suggested that the effect of the solution of C, which was produced in the preparation process, also can not be ignored for such a composite.
Microstructure and Magnetic Properties of Hot-Pressed and Hot-Deformed Composite Magnets Produced by Spark Plasma Sintering Method
Authors: Ma Yi Long , Chen Deng Ming , Shen Qian , Cao Peng Jun
Published: June 2011

Bulk isotropic and anisotropic Nd13.5Fe80.4Ga0.5B5.6 and Nd13.5Fe80.4Ga0.5B5.6/Fe magnets were synthesized by applying spark plasma sintering (SPS) technique. The effect of hot-pressing temperature on the magnetic properties of hot-pressed (HP) and hot-deformed (HD) magnets without additive and with 5% Fe addition was investigated. With increasing sintering temperature for HP magnets, the grain grew gradually. For HD magnets, the optimal magnetic properties could be obtained at hot-pressing temperature 680°C due to the development of desired c-axis texture and uniform microstructure, which resulted from the appropriate and uniform grain size in HP magnets. Fe addition could enhance remanence (Br) and magnetic energy products ((BH)m) of HP and HD magnets. However, the maximum magnetic energy product of HD magnets decreased when hot-pressing temperature was higher than 650°C.
The Interface Investigation and Tribological Mechanism of TiB2-TiC-Ni/TiAl/Ti Functionally Gradient Materials Prepared by FAPAS Process
Authors: Hu Li Fang , Liang L.J. , Chen Shao Ping , Xue P.F. , Wang F.M. , Meng Qing Sen
Published: June 2011

TiB2-TiC-Ni/TiAl/Ti functionally gradient materials were prepared by Field-activated pressure-assisted synthesis (FAPAS). Microstructure, elements distribution and phase composition of the interface were mainly investigated by SEM, EDS and OM. The results showed that the particles of TiB2-TiC composite ceramics were fine and homogeneously dispersed. The friction coefficient and wear rate of the synthesized ceramic were lower at elevated temperature and high load. The oxide films of Fe2O3, TiO2 and B2O3 formed during the friction process play an important role in the lubrication. Oxidized products greatly reduce the friction coefficient of TiB2-TiC-Ni ceramics at 400°Cor above.
Encapsulating and Manufacture Technology Study of Impact-Resisting, Enclosed Soft Aramid Vesicle
Authors: Liu Yong , Wang Xin , Ding Yu Mei , Yang Wei Min
Published: June 2011

In order to get a soft and enclosed vesicle which can endure an instantaneous high temperature and super high pressure the soaking technology of aramid fiber with Room Temperature Vulcanization silicon rubber and liquid polyurethane was studied. Then the performance of the composites was tested. Two kinds of rubber vesicle were made, one with metal valve and another without the valve. Using three-dimension braid method, aramid fiber vesicle was made outside the rubber vesicle. Compression test results of the composite vesicle showed that no-valve rubber vesicle had a good match with the aramid one and endured a very large pressure. It can transfer the liquid pressure from inner vesicle to the outer one, which the aramid fiber has excellent mechanical performance and can endure a very large compression.
A New Sand Casting Process with Accelerated Solidification Rate
Authors: Zeng Jian Min , Zhou Yao He
Published: June 2011

In order to solve the problems involved in coarse grains, macro and micro porosities initiated by low solidification rate in sand casting, an innovative counter-gravity sand casting process, Casing under Adjustable Pressure with Accelerated Solidification (CAPAS) was put forward in this paper. The hydrodynamics of mold filling for CAPAS is based on Bernoulli's principle. The mold and crucible were placed separately in the upper and lower chambers, with the feed tube connected between them. High-speed jet flow of air made negative pressure in the upper chamber. In this way, pressure differential was created between the two chambers. Thereby the molten metal in the crucible was forced to flow upward smoothly to fill the mold cavity. After mold filling, cold air was introduced into sand mold through aisles that are set within the mold, which results in strong convective heat exchange at the casting/mold interface. So solidification rate of casting increased dramatically. The microstructures of the aluminum castings were compared between CAP (Low pressure sand casting) and CAPAS by optical microscope. The results showed that the microstructure of CAPAS aluminum casting was much finer than that of CAP casting and tensile strength markedly increased.
Effect of the Rolling Process on Microstructures and Mechanical Properties of the Extruded LA91 Alloy Sheet
Authors: Jiang Bin , Yang Qing Shan , Gao Liang , Pan Fu Sheng
Published: June 2011

The microstructure evolution of the extruded Mg-9Li-1Al (LA91) during rolling was investigated taking account of effects of different routes including hot rolling, and cross rolling. The rolling parameters were suggested by thermal compression testing. As a result, the suggested rolling parameters were 250°C and 1.0s-1. Transverse hot rolling would bring a finer microstructure to the as-rolled LA91 sheet. With the enhancement of the rolling reduction during unidirectional hot rolling the α-Mg phase became granular or short rod-like from long strip-like. Transverse + longitudinal hot rolling would improve the microstructure and was a better cross rolling route by which the strength and the elongation of the cross rolled LA91 sheet reached 243MPa and 20% respectively. The over-aging existed in the cross rolled LA91 sheets.
A HRTEM Study of Resistive Switching Behaviour in SiO2 Thin Films by Sol-Gel Process
Authors: Li Ying , Zhao Gao Yang , Zhou Xiao Fei , Pan Li Ning , Ren Yang
Published: June 2011

Amorphous SiO2 thin films were fabricated at different temperatures using sol-gel technique. The unipolar resistive switching behavior was observed in Cu/ SiO2/ ATO (SnO2: Sb) sandwiched structure when the SiO2 thin film annealed at 500°C. The average ratio of Roff /Ron is 102. We investigated the successful device using HRTEM and XPS. It shows that the Cu defuses into the SiO2 thin film and it forms CuSiO3 in the interface between SiO2 and ATO films according to the high resolution images.
Microstructure and Dielectric Properties of BaTiO3-Based Ferroelectric Materials
Authors: Fu Chun Lin , Cai Wei , Deng Xiao Ling
Published: June 2011

The microstructure and dielectric properties of BaTiO3-based ceramics and films were investigated. In BaZr0.2Ti0.8O3 ceramics domains with herribone, lamellar and “water-mark” characters are observed and 90◦-domain has not been observed in large grain size sample. It is shown that the average grain size and the remanent polarization of doped BZT ceramics decrease with the increasing of Al content. The dielectric constant and tunability of the BaZr0.2Ti0.8O3 films using inorganic zirconate are 113 and 10.2%, respectively. It is found that nanowires of BaTiO3 annealed for 2.5 min are very clear-cut, orderly and almost uninterrupted.
Structure and Electrical Properties of PbTiO3-CoFe2O4 Magnetoelectric Composites
Authors: Liu Jing Song , Xu You Chao , Li Tao
Published: June 2011

0-3 type magnetoelectric(ME) composites of PbTiO3(PT) and CoFe2O4(CFO) were prepared by a conventional solid-state reaction method with different volume fraction. The composites exhibited ferroelectric phase and ferromagnetic phase coexisting. The ferroelectric and magnetic properties of as-sintered samples were measured. The magnetic properties change regularly with the test frequency. But the dielectric permittivity shows the anomalies, which can be attributed to constraints and dilutions from the ferromagnetic phase and the element diffusion.
The Improvement of Performance of HfO2/Gd2O3/Si Stack Compared with Gd-Doped HfO2 High-K Films
Authors: Wang Xiao Na , Zhang Xin Qiang , Xiong Yu Hua , Du Jun , Yang Meng Meng , Wang Lei , Tu Hai Ling
Published: June 2011

HfO2/Gd2O3/Si stack and Gd-doped HfO2 (GDH) High-k films have been grown on p-type Si (001) substrates by RF sputtering. The amorphous structures of GDH high k film which be grown and annealed at 700°C have been determined by HRTEM. There is a interface layer between Gd2O3 film and Si in HfO2/Gd2O3/Si stack. XPS measurement reveals that the peak shift to small binding energy for Hf4f due to the formation of Hf-O-Gd, and there are formations of gadolinium and hafnium silicate. A leakage current density of 1×10-6 A/cm2 at -1 V, a hysteresis voltage of 13 mV, a dielectric constant of 23 and a CET of 1 nm are obtained from a capacitor with Pt/HfO2/Gd2O3/Si/Ag stack through C-V and I-V measurements. In addition, the HfO2/Gd2O3/Si stack film has a higher breakdown voltage (~ 30 V) than that of GDH films.
Effect of Composite Additives on ZnO Varistor Ceramics
Authors: Zhu Jian Feng , Qi Guo Quan , Yang Hai Bo , Wang Fen
Published: June 2011

ZnO-based varistor ceramics were prepared by sintering ZnO powders with minor additives that were synthesized by standard ball milling, high energy ball milling for 10 h, and pyrogenic decomposition of nitrate. The microscopic structure and composition were analyzed by SEM and XRD respectively, and the electrical properties were investigated by a DC parameter instrument for varistors. Influences of composite additives on composition, microstructure, and electrical properties of ZnO-based varistors were studied. The ZnO varistor with optimum performance is prepared by the pyrogenic decomposition method and it has an average grain size of 5 µm and possesses a varistor voltage of about 561 V/mm, non linear coefficient of 75, and leakage current of 0.45 µA.
Low-Temperature Sintering of ZnO and B2O3 Co-Doped (K0.5Na0.5)NbO3 Lead-Free Piezoelectric Ceramics
Authors: Huang Rong Xia , Zhao Yu Zhen , Zhao Yong Jie , Liu Rong Zheng , Zhou He Ping
Published: June 2011

Lead-free K0.5Na0.5NbO3-xwt% (0.4ZnO-0.6B2O3) ceramics were synthesized by conventional ceramics process. The co-doping of ZnO and B2O3can decrease the sintering temperature of K0.5Na0.5NbO3ceramics to 1000°C, and the samples show high relative density around 96%. X-ray diffraction (XRD) reveals that Co-doping of ZnO and B2O3induces lattice distortion. Liquid phase is observed by scanning electron microscopy (SEM), which is resulted from the addition of ZnO and B2O3. The ceramics show better piezoelectric and dielectric properties with planar electromechanical coupling factorkp= 40.7%, piezoelectric constantd33=117pC/N, dielectric constantεT33/ε0=318.6, and loss tangenttanδ=0.034.
Effect of Pr on the Microstructure and Electrical Properties of Ta-Doped TiO2 Capacitor-Varistor Ceramics
Authors: Wang Tian Guo , Qin Qun , Zhou Dong Jian
Published: June 2011

TiO2 varistors doped with 0.1 mol% Ta and different concentrations of Pr3+ were obtained by ceramic sintering processing at 1400 °C and their properties were characterized by XRD, SEM, I-V and impedance spectroscopy. The effect of Pr on the microstructure, nonlinear electrical behavior and dielectric properties of the Ta-doped TiO2 ceramics were investigated. It is found that Pr affects the grain size, electrical properties and the dielectric properties of the TiO2-based varistors. The samples have the nonlinear coefficients (α) values of (3.0-5.0) with low breakdown voltages (4-30 V/mm). A small quantities of Pr can improve the nonlinear properties of the samples significantly. It was found that an optimal doping composition of 0.5 mol% Pr3+ leads to a low breakdown voltage of 9.2 V/mm, a high nonlinear constant of 4.9 and an ultrahigh electrical permittivity of 8.38×104 (at 1 kHz), which is consistent with the highest grain boundary barriers of the ceramics. In view of these electrical characteristics, the TiO2-0.5 mol% Pr3+ceramic is a viable candidate for capacitor-varistor functional devices. The defects theory was introduced to explain the nonlinear electrical behavior of Pr-doped TiO2 ceramics.
Preparation and Property of BaTiO3/PVDF Composites
Authors: Ma Li , Gong Zhao Quan , Liu Yong Qin , He Qi Zhuang , Xu Dong Fang , Sun Da Zhi
Published: June 2011

Ferroelectric BaTiO3/polyvinylidene fluoride (BaTiO3/PVDF) composites were prepared by a coating technique. It was observed that BaTiO3powders prepared with different thermal treatment temperatures affected dielectric performances of the composites. The polymer with fine BaTiO3powder exhibited a lower dielectric loss than that with coarse powder. Fourier transform infrared spectrum was carried out to investigate the vibration of chemical bonds. The relationship between the dielectric property and intercoupling between F-ion and oxygen octahedron was discussed.
Relaxation Behavior of Zr Substituted CaCu3Ti4O12 Ceramics
Authors: Yu Hong Tao , Zhang Wen Bo , Liu Jing Song , Liu Han Xing
Published: June 2011

The dielectric properties of Zr substituted CaCu3Ti4O12ceramics have been investigated in detail. Grain size decreases with Zr content increasing. The hetero-electrical microstructures of prepared samples have been confirmed by the impedance spectra. The dielectric loss has been improved by Zr doping because of the enhancement of grain boundary resistivity. A Debye-like boundary relaxation behavior has been observed in the temperature range of 220-600K. As Zr content increases, the relaxation time increases due to the higher grain boundary concentration. This work has provided an additional proof for the origin of giant dielectric response in CaCu3Ti4O12ceramics.
Structural and Electrical Properties of BiFeO3 Fabricated on C-Sapphire Substrates Using a Double SrTiO3/TiO2 Buffer Layer
Authors: Liao Xiu Wei , Zhu Jun , Luo Wen Bo , Hao Lan Zhong
Published: June 2011

BiFeO3 (BFO) thin films were deposited by pulsed laser deposition (PLD) on c-plane sapphire substrates with a double SrTiO3/TiO2 oxide buffer layer grown by laser molecular beam epitaxy (laser-MBE). X-ray diffraction data showed the highly (111)-oriented perovskite phase in the BFO films with SrTiO3/TiO2 buffer layers, compared to the polycrystalline thin film grown directly on sapphire substrates. The epitaxial BiFeO3 thin films inherit its orientation from the underlying SrTiO3 buffer layer and have two in-plane orientations: (111)[1-10] BiFeO3 // (0001)[1-100] Al2O3 plus a twin variant related by a 180° in-plane rotation. The BiFeO3 thin films with the buffer layer show an out-of-plane remanent polarization of 81.5μC/cm2, which is comparable to the remanent polarization of BiFeO3 prepared on other single crystal substrates. Electrical measurements demonstrate that the BiFeO3 thin films with the buffer layer exhibit excellent fatigue endurance and a low leakage current density relative to the films without the buffer layer. These results indicate that the (111)-oriented BiFeO3 films with favorable electrical performance could be epitaxially grown on sapphire substrates using the double SrTiO3/TiO2 buffer layer.
Study of Structural and Dielectric Properties of Ba0.6Sr0.4(ZrXTi1-X)O3 Ceramic
Authors: Wang Xi Lin , Zhao Yu Zhen , Liu Shan Shan , Zhou He Ping
Published: June 2011

BaxSr1-xTiO3[(BST), 0£x£1] is a solid solution ferroelectric material exhibiting a large dielectric constant non-linear change with an applied DC electric field. And Ba(ZrxTi1-x)O3solid solution also has received much attention because of the good tunbality. In this paper, Ba0.6Sr0.4(ZrxTi1-x)O3(x=0.15,0.20,0.25,0.30,) ceramic was obtained by traditional ceramic processing. The structural, surface morphological, dielectric properties, tunable properties of this material as well as the mechanism of their nonlinear dielectric constant under DC electric field were systematically examined. The Zr ions substitution of Ti ions has a strong effect on the grain sizes and the dielectric property. The results show that Ba0.6Sr0.4(ZrxTi1-x)O3(x = 0.2, 0.25,0.3) ceramic is a promising candidate for the DC electric field tunable materials for microwave electronics application, because they exhibit high relative tunability (44%, 48%, 35%, respectively) as the strength of electric field is up to 1.5 kV/mm, and low dielectric loss (0.0026, 0.00044, 0.0015, respectively) at 100 kHz at room temperature. X-ray diffraction analyses indicated that the samples present perovskite phase. Scanning electron microscopy micrograph of sample indicated that the grain size decreased and density increased with Zr concentration increasing.
Study on the Effects of (Bi1/2Na1/2)TiO3 Content on the Curie Temperature of (Bi1/2Na1/2)TiO3-BaTiO3 PTCR Ceramics
Authors: Yang Long Xing , Zhu Xing Wen , Li Li Zhe , Jiang Wen Zhong , Zhou Xiao
Published: June 2011

Perovskite-structured (Bi1/2Na1/2)TiO3 (BNT) ferroelectric with Curie temperature about 320°C is considered to be a good candidate of high temperature lead-free materials with a positive temperature coefficient of resistance (PTCR). In this study, lead-free PTCR ceramics with compositions of (1-x)BaTiO3-x(Bi1/2Na1/2)TiO3 (BT-BNT x=0.5-55mol%) were successfully prepared without any additional donor or acceptor dopants. The effects of BNT content on the Curie temperature Tc and the PTC effect of the ceramic materials were investigated. The X-ray diffraction data indicated that BT phase and BNT phase formed a solid solution during sintering even though the x value was up to 55mol%. The Curie temperature Tc of the samples increased from ~130°C to ~216°C with the increase of the BNT amount (x value) from 0.5mol% to 40mol%. However, it decreased when excess BNT was added (x value increased from 40mol% up to 55mol%), which was resulted from the volatile effects of Bi3+ and Na+ ions during sintering. The sample of 0.6BaTiO3- 0.4(Bi1/2Na1/2)TiO3 with Tc =216°C, room-temperature resistivity 104 Ω·cm and Rmax/Rmin= 102.7 was obtained. There is a relationship between the Curie temperature and the cell volume of the perovskite structured lattice.
The Influence of Doped MgF2 on the Dielectric Properties of Barium Strontium Titanate Ceramics
Authors: Liu Shan Shan , Zhao Yu Zhen , Wang Xi Lin , Zhou He Ping
Published: June 2011

Barium-strontium titanate Ba1-xSrxTiO3[0≤x≤1] has been investigated for tunable microwave application due to their high permittivity, low losses and high tunability. The influence of MgF2additives on the dielectric performance of Ba0.6Sr0.4TiO3(BSTO) were investigated in this paper. MgF2doped BSTO ceramics were prepared using the conventional mixed oxide techniques. The phase structure, microstructure and dielectric properties of MgF2doped BSTO ceramics were studied. The XRD patterns showed that all the samples exhibit a perovskite phase. A secondary phase of MgO was observed with excessive MgF2additives. The grain size of MgF2doped BSTO ceramics was slightly increased with the increasing of MgF2additives, while the distributed porosity was concentrated to get larger. The relative permittivity, dielectric loss and tunability were decreased accordingly. The relative permittivity was reduced from 3717 (pure Ba0.6Sr0.4TiO3) to 680 (6 wt % MgF2doped BSTO), while the tunability changed from 51.7 % to 6.5 %. The dielectric losses were decreased from 0.004 to less than 0.001. The Curie temperature of MgF2doped BSTO was first decreased with the additives of MgF2(x<2 wt %) then remain the same with the rise of MgF2(2≤x≤6) content.
Vickers Hardness Studies on (001) and (110) Faces of DAST Crystal
Authors: Xu Hui , Teng Bing , Yu Zheng He , You Fei , Zhong De Gao , Zhang Shi Ming , Yu Yue Juan , Ma Jiang Tao
Published: June 2011

4-Dimethylamino-N-methyl 4-Stilbazolium Tosylate（DAST） crystals were prepared by the slope nucleation method. The Vickers hardness of DAST crystal was studied on (001) and (110) faces. It was found that the Vickers hardness increases with increasing load and theHvon (001) face is higher than that on (110) face. The values of Meyer’s index numbernand hardness were calculated fromHv. The results showed that the DAST crystals belong to the soft material category.
Gold Thin Film as Transition Layer in Electrode Design of Na2O−PbO−Nb2O5−SiO2 Glass-Ceramic Capacitors
Authors: Zhu Jun , Luo Jun , Zhang Qing Meng , Tang Qun , Du Jun
Published: June 2011

The electrical properties and microstructure of Na2O−PbO−Nb2O5−SiO2 glass-ceramic capacitors with pre-sputtered gold film as the transition layer in electrode design were investigated. SEM observation and EDS analysis showed that the presence of gold transition layer would eliminate enormously the Ag diffusion into the dielectric layer, resulting in a smooth and dense interface contact with less porous defects near the electrode/dielectric layer region. The electrical property results indicated that the leakage current and dielectric loss had decreased by about an order of magnitude and 20%, respectively. These results were explained by the weakened diffusion of silver into dielectric layer due to the presence of gold transition layer in between the silver paste/dielectric interface.
Effect of Temperature on Critical Stress for Slip of Ti-Ni Shape Memory Alloy
Authors: Yamamoto Takaei , Cho Hiroki , Sakuma Toshio
Published: June 2011

This study describes the effect of temperature on critical stress for slip of Ti-Ni shape memory alloy. Tensile loading-unloading tests has been carried out using Ti-50.3at%Ni in the temperature range from 193K to 423K in order to investigate the temperature dependence of critical stress for slip of Ti-Ni shape memory alloy. The critical stress for slip is different in the three regions which are the martensitic single phase state in the range of 193K-273K, the mixture state of the martensitic and parent phases in the range of 273K-373K and the parent single phase state in the range of 373K-423K. The critical stress for slip of the martensitic single phase is about 200MPa. In the case of the mixture state of the martensitic and parent phases, the critical stress for slip increases with increasing temperature, and reaches the maximum stress of 652MPa at 373K. The critical stress for slip of the parent phase decreases with increasing temperature.
<Hysteresis Property of Stress-Strain Relation for Tb0.3Dy0.7Fe2 <110> Oriented Polycrystal
Authors: Wang Bo Wen , Wang Zhi Hua , Hao Yan Ming , Yi Yu Fa , Weng Ling , Huang Wen Mei
Published: June 2011

The Tb0.3Dy0.7Fe2 <110> oriented alloy was grown by zone melting directional solidification technique. The strain-stress loops of the alloy in different magnetic fields have been measured, and the effect of stress and magnetic field on strain difference Dε has been confirmed. It is found that the strain difference Dε quickly increases with increasing the stress when the stress is less than 10 MPa and decreases in the range of 10-40 MPa when the magnetic field is in the range of 30-40 kA/m. The result indicates that the magnetic field and stress have a marked effect on the strain hysteresis of the Tb0.3Dy0.7Fe2 <110> oriented alloy and the hysteresis property of stress-strain relation should be considered during the design of magnetostrictive sensors.
Synthesis and Performance of Super Absorbent Resin with Acrylic Acid-Acrylamide
Authors: Li Ting Xi , Kong Na , Wu Sha Sha , Gao Su Su , Sui Peng , Li Shan Ting
Published: June 2011

Super absorbent resin acrylic acid-acrylamide (P (AA-AM)) was synthesized by water solution copolymerization method using acrylic acid (AA) and acrylamide (AM) as monomer, potassium persulfate as initiator, aluminum hydroxide as crosslinking agent. The effects of mole ratio of acrylamide (AM) to acrylic acid (AA), degree of neutralization of AA, the amount of crosslinking agent and initiator, and reaction temperature on absorbing water performance influence was inspected.
Superhydrophobic Coatings Prepared by Micro/nano Particles Mixed with Fluorocarbon Resin
Authors: Qi Yu Hong , Zhang Zhan Ping , Wang Jing Zhao , Chen Ya Meng
Published: June 2011

In this paper, single and multilayer superhydrophobic composite coatings, based on fluorocarbon resin and micro-tourmaline and nano-TiO2powers, were prepared by conventional air spray method. The tourmaline and TiO2particles were modified by fluoroalkylsilane. The wettability and marine corrosion of the coatings surfaces were investigated respectively by contact angle measurement and Electrochemical Impedance Spectroscopy (EIS) method, and their morphology was examined by Scanning Electron Microscopy (SEM). The results showed that the water contact angle of coatings was mainly controlled by the mass ratio of the fluorocarbon resin and particles. The contact angle increased with the increase of particle concentration, which reached about 156° when the mass ratio of the particles and fluorocarbon resin was 2:1 for single and multilayer composite coatings, but the impedance valve of the multilayer is higher than that of the single layer.
Microstructure and Wear-Resistant SiC Film by RF Magnetron Sputtering
Authors: Tian K. , Xu Xiao Jing , Fan Zhen , Hao Xin Ni , Chen Dan , Xin Xi Ling , Sheng Xin Lan
Published: June 2011

A wear-resistant SiC (silicon carbon) film on titanium substrate was prepared by magnetron sputtering technology. The film exhibits low nano-hardness of 12.1 GPa and low Young's modulus of 166.2 GPa together with superior friction/wear properties. As sliding against Si3N4 (silicon nitride) ball (2 mm in radius) at room temperature under Kokubo simulation body fluid condition, the film exhibited the friction coefficient of about 0.215 and the special wear rate in the order of magnitude of 10−5 mm3/ Nm even at the load of 500g without film cracking and interface delaminating. The high film-cracking and interface-delaminating resistance is due to the low hardness of the film and the good film/substrate modulus match caused by the low elastic modulus of the film.
Conversion of Surface Energy and Experimental Investigation on the Self-Motion Behaviors of Liquid Droplets on Gradient Surfaces
Authors: Liu Chang Song , Zhou Ji Gen , Zheng Dong Mei , Wan Yong , Li Zhi Wen
Published: June 2011

A surface with surface energy gradient was fabricated by using a controlled photodegradation technique of a fluoroalkylsilane self-assembled monolayer (SAM) using irradiation of vacuum ultraviolet light (wavelength=172 nm). Visualization experiments were carried out to investigate the motion behaviors of water droplets on horizontal gradient surfaces. System free energy conversion was analyzed to understand the mechanics of the droplet self-motion. The results show that the liquid droplets were self-propelled to move from hydrophobic region to hydrophilic region on horizontal gradient surfaces. The motion process of the water droplet experienced an accelerating stage and a decelerating stage. The velocity of 2 mL water droplet reached to a maximum of 23.28 mm/s. In the droplet motion on the horizontal gradient surface, the deformation and spread of the droplet continuously release out the interfacial and gravitational potential energy, which offers the kinetic energy for the droplet motion. However, the released interfacial energy is three orders of magnitude larger than the released gravitational potential energy. Thus, the released interfacial energy is the main source of driven energy for the droplet motion. The theoretical analysis is consistent with the experimental results.
Effect of Blending with Additives on Mechanical Properties of PVC Architectural Membrane Material
Authors: Meng Yu Gang , Huo Rui Ting , Qi Chun Zhi , Chang Ling Yu
Published: June 2011

Polyvinyl chloride (PVC) architectural membrane material is a species of composite textile material. In comparison with other architectural membrane materials such as PTFE or ETFE, PVC membrane material is much cheaper, softer and easier construction feasibility. In this paper, g-methacryloxypropyl trimethoxy silane (KH-570), chlorinated polyethylene (CPE) and pellet binder (PB) were added into PVC paste, respectively. The mechanical properties (tensile strength, peel strength and tearing strength) of the coated fabric were investigated. It was found that the mechanical characteristics of PVC coated fabric were evidently affected by the addition of KH-570 in the coating paste. Both tensile strength and peel strength of PVC coated fabric were improved by the addition of KH-570. The addition of CPE into the coating paste had little effect on the mechanical properties of the coated fabric. The mechanical properties of the coated fabric were greatly improved by blending with PB, the peel strength enhanced 157% and the tensile strength increased 150N/50mm, but the tearing strength was largely reduced.
Effect of Different Dielectric Constant Solvents Addition on PEDOT-PSS Conductive Polymer and its Application
Authors: Lee Chin Jung , Tsai I Shou
Published: June 2011

This paper investigates the physical properties of conductive paste which is used for print engineering. The conductivity of poly (3,4-ethylenedioxythiophene) (PEDOT) doped with poly(4-styrenesulfonate) (PSS) containing various organic solvents was measured. The different dielectric constant solvents are isopropanol, N-methyl-2-pyrrolidone, N,N-dimethyl acetamide, dimethyl sulfoxide with different concentration. After drying, they were prepared many kinds of films. It was found that an addition of organic solvent lowered the resistance by two or three orders of magnitude when the concentration is 25wt% , among them the larger dielectric constant solvent has the best surface conductivity, the magnitude is about 7.03×10－1S/cm, and then we blend every two solvents by 25wt% concentration, prepared six blend films. Among them has the best effect, the magnitude is about 1.94×10-1S/cm. All kind of PEDOT/PSS films have been studied using four point probe conductive meter, X-ray diffractometry (XRD), fourier transform infrared (FTIR), thermogravimetric analysis(TGA) in order to discuss the surface conductivity, the crystallinity, the chemical structure and the thermal properties of the PEDOT/PSS film. Conducting PEDOT/PSS-IPA/DMSO solution mix with polymethyl-methacrylate (PMMA) resin to coat hydrophobic fabrics, which can be used for the dissipation of electrostatic charge.
Influence of Additive on Diamond Films Synthesized Using Liquid Phase Electrochemical Method
Authors: Zhang G.F. , He Y.Y. , Hou X.D.
Published: June 2011

An attempt was made to deposit nano-crystalline (or amorphous) diamond films on silicon and 316L stainless steel substrates by electrochemical deposition using a high-voltage pulsed generator. Alcoholic organic compounds with various concentrations of deionized water were used as electrolysis solutions. The surface morphology and crystal structure of the films were examined by scanning electron microscopy and Raman spectroscopy. Adding de-ionized water into the reaction solution can enhance the deposition rate of amorphous diamond films. The crystalline structure analysis has confirmed unambiguously the formation of diamond nano- or submicron-crystals in the deposits. It is believed that the ion H of electrochemical production plays quite similar roles to those that take place in chemical vapor deposition methods of diamond growth.
K-Type Thin Film Thermocouples Deposited on Ni-Based Superalloy Substrates
Authors: Chen Y. Z. , Wang C. R. , Jiang Hong Chuan , Zhang Wan Li , Liu X.Z. , Li Yan Rong
Published: June 2011

NiCr-NiSi K-type thin film thermocouples with multi-layer structure were fabricated on Ni-based superalloy substrates (95 mm×35 mm×2 mm). The multi-layer structure contains NiCrAlY buffer layer (2 μm)/ thermally grown Al2O3 bond coating (200 nm)/ Al2O3 insulating layer (8 μm)/ NiCr-NiSi thin film thermocouples (1 μm)/ Al2O3 protecting layer (500 nm). The samples were statically calibrated in a tube furnace in the temperature range from 170 °C to 610 °C. The results show that the resistance of Al2O3 insulating layer is about 14.6 kΩ at 800 °C and exceeds 100 MΩ at room temperature. The Seebeck coefficient a of the samples is about 34 μV/°C, and the sensitivity coefficient K is greater than 0.8 in the temperature range from 170 °C to 610 °C. The maximal sensitivity coefficient is about 0.97 at 265 °C.
Ab Initio Study on Hexagonal Ge2Sb2Te5-A Phase-Change Material for Nonvolatile Memories
Authors: Sun Zhi Mei , Pan Yuan Chun , Sa Bai Sheng , Zhou Jian
Published: June 2011

On the basis of ab initio total energy calculations, we have performed an extensive study on the stacking sequence and random occupation of Ge and Sb to make the same layer in stable hexagonal Ge2Sb2Te5 (h-GST), an excellent candidate for phase change random memory applications. The results demonstrate that the atomic arrangements have great effects on lattice parameter c and electronic properties of h-GST. h-GST changes from semiconductor to metallic behavior as varying the atomic sequence.
Optically Transparent of N-ZnO/p-NiO Heterojunction for Ultraviolet Photodetector Application
Authors: Tsai Shu Yi , Hon Min Hsiung , Lu Yang Ming
Published: June 2011

Transparent p–n heterojunction diodes consisting of n-type ZnO and p-type NiO thin films were prepared on glass substrates by r.f. magnetron sputtering. The structural and optical properties of the n-ZnO/p-NiO heterojunction were characterized by X-ray diffraction (XRD), UV–visible spectroscopy, Hall measurement, and I-V photocurrent measurements. The XRD shows that ZnO films are highly crystalline in nature with preferred orientation along the (0 0 2) orientation. The optical transmittances of ZnO and NiO films are 87% and 80%, respectively. The current–voltage curve of the heterojunction demonstrates obvious rectifying diode behavior in a dark environment. The lowest of leakage current is 7.73x10−8 A/cm2 for n-ZnO/p-NiO heterojunction diode. Upon UV irradiation, it was found that the detector current was increased by more than one order of magnitude. It was also found that the corresponding time constant for turn-on transient was τon = 27.9 ms while that for turn-off transient was τoff= 62.8 ms.
Synthesis of Porous TiO2 Thin Films via Sol-Gel Method and their Phototocatalyst Performances
Authors: Yao Jian Xi , Tian Zhi Hua , Guli Mi Na , Takahashi Masahide , Yoko Toshinobu
Published: June 2011

Macroporous TiO2films have been prepared by sol-gel method without any surfactant and colloidal templates. The gel TiO2films deposited from the precursor solutions containing photo monomer were irradiated by the UV light for some time. The UV irradiation could induce the monomer to polymerize, which resulted in two phases in the films, one was the emerging polymer rich phase, and another was the residual monomer-TiO2oligomer rich phase. After heat-treatment, a well-defined interconnected macroporous TiO2films could be obtained. SEM and AFM results showed that the macroporous structures of the films could be tuned by changing the reaction parameters. The as-prepared macroporous TiO2films exhibited much higher photocatalytic activity for the photodecomposition of methylene blue dye than that of the dense film.
VO2 Films by Polymer-Assisted Deposition: Investigation of Thermal Decomposition of Precursor Gel and Control of Phase Transition Temperatures
Authors: Kang Li Tao , Gao Yan Feng , Luo Hong Jie
Published: June 2011

Polymer-assisted deposition (PAD) can be employed to prepare metal oxide films by coordination between metal ions and polymers instead of hydrolysis and condensation reactions, providing a cheap and scalable alternative for sol-gel process. This work involves a TG/DTA-MS study on the thermal decomposition of the precursor gel to form VO2 films. The results show that polymers influence effectively the achievement of thermochromic VO2, supporting the film-forming mechanism we proposed in a previous work. W-doping shifted the MIT temperature from 58 to 33 °C while remained 73% of the modulating ability in infrared transmittance at 2000 nm.
Controlled Growth and Supercapacitive Behaviors of CVD Carbon Nanotube Arrays
Authors: Zhao Dan Dan , Yang Zhi , Wei Hao , Zhang Ya Fei
Published: June 2011

Low-pressure chemical vapor deposition (LP-CVD) technique has been utilized for controlled growth of carbon nanotube (CNT) arrays on silicon wafers. The tube-diameters of CNTs and the number of graphene layers are controlled by varying the thickness of catalyst films. The catalyst particle density and the growth conditions such as the ambient gas and the local environment are all crucial for the formation of vertically aligned CNT arrays. The length of CNT arrays can be controlled by altering the growth time. In addition, the supercapacitive properties of CNT arrays with various morphologies growing on different current collectors have been investigated using a less corrosive 0.5 M Na2SO4aqueous solution as the electrolyte. Vertically aligned CNT arrays on Ti-Si substrate produce a higher capacitance compared to randomly oriented CNTs on the same current collector. Furthermore, Ni foam enables better utilization of active materials than Ti-Si substrate. CNT arrays electrodes fabricated by this simple, low cost approach demonstrate stable and consistent capacitor behaviors for a wide range of scan rates. Moreover, CNT arrays electrodes provide better platform for further integration with transitional metal oxide, via simple sputtering or electrodeposition technique, to enhance the supercapacitive performance.
Flame Synthesis of Carbon Nanotubes and Nanocapsules
Authors: Ding Zhao Yong , Sun Bao Min , Jia Bin , Ding Xiao Lian
Published: June 2011

Flame synthesis of carbon nanotubes and nanocapsules is demonstrated via a pyramid-shaped pyrolysis flame. The mixture of CO, H2, and nebulized catalyst raw material reacts in a high temperature environment formed inside the frustum of pyramid-shaped reactor heated by premixed flame of C2H2and air outside. A sampling substrate inserted into the incomplete combusting flame of central reacting mixtures can gain the samples of carbon nanotubes and nanocapsules. The effect of sampling time and catalyst concentration is revealed via Field emission scanning electron microscope (FE-SEM) and High-resolution transmission electron microscopy (HR-TEM). 5-mins sampling time and 0.5/50 (Fe(CO)5/C2H5OH, volume ratio) of catalyst concentration is the most appropriate for carbon nanotubes synthesis. In addition, it is to say that catalyst concentration is the most important one among all the factors that can be used to determine whether the main products are carbon nanotubes or nanocapsules, and the structures of nanocapsules are also analyzed in detail.
Germanium Dioxide Nanocubes with Different Size Distributions and Its Gibbs Free Energy Theory
Authors: Wang H. , Tao Y. , Zhang G.Q. , Xia Y.P. , Gong F.H. , Wu H.P. , Tao G.L.
Published: June 2011

A simple synthesis method for single crystal GeO2 nanocubes in a reverse micelle system was reported here. Hydrolysis of germanium tetrachloride (GeCl4) in a micelle system produces GeO2nanocubes in the presence of oleylamine and cetyltrimethylammonium (CTAB). We found that we could obtain GeO2nanocubes with monodisperse size distribution, bimodal size distribution and polydisperse size distribution by varying the reaction parameters. We put forward a feasible explain for this phenomenon with using Gibbs free energy theory, and this theory can give some meaningful guidance for preparing monodisperse nanomaterials.
Microstructure and Mechanical Properties of SiC/Al Nanocomposite
Authors: Gu Wan Li , Sun Ming , Wang Xin Guang , Sheng Wen Bin , Zhu Guang Ming
Published: June 2011

In this paper, nanozised SiC particle has been chemically treated with acetone and hydrofluoric (HF) and then electroless plating with CuSiO4and HCHO solution subsequently. The results show that the nanosized SiC particle can be deposited with Cu coatings and made them more likely distributed in aluminum powder homogenously. Bulk SiC/Al nanocomposite prepared by hot pressing and the mechanical property of the composite were studied. The clothed SiC particle has an easier distribution in aluminum matrix than ordinary SiC particle and the corresponding composite has a higher strength and hardness.
Production of Helical Polymer Microfibers by Electrospinning
Authors: Tang Cheng Chun , Long Yun Ze , Chen Jun Chi
Published: June 2011

Curled polyvinylpyrrolidone (PVP) microfibers were prepared successfully with a modified electrospinning setup in which the commonly used collector, a piece of aluminum foil was replaced by a steel nail (a tip collector). PVP (45 wt %) ethanol solution was used.with the increase of voltage, the proportion of the curled fibers increased and the uniformity of the curled fibers improved, also the repeat distance (wavelength) of the curled structures became smaller. In addition, some curled fibers developed into helical structures under relatively high voltages. Further analyses suggest that the mechanism for the curled PVP fibers could be ascribed to electric driven bending instability and/or mechanical jet buckling when hitting the hard collector surface.
Thermophysical Properties of Al2O3-Water Nanofluids
Authors: Zhu Bao Jie , Zhao Wei Lin , Li Jin Kai , Guan Yan Xiang , Li Dong Dong
Published: June 2011

Aqueous nanofluids composed of alumina nanoparticles with different sizes at a concentration from 0.1vol% to 0.5vol% were prepared by a two-step method. The suspension and dispersion characteristics were experimentally examined by zeta potential, average size and absorption spectrum. The thermophysical properties such as the viscosity, surface tension, thermal conductivity, saturation vapor pressure and latent heat of vaporization were measured. The influences of the particle size, particle volume concentration and temperature on the thermophysical property were investigated. It was found that the viscosity and thermal conductivity increased with decreasing nanoparticle size. In contrast, the surface tension, saturation vapor pressure and latent heat of vaporization decrease with decreasing nanoparticle size. The viscosity, thermal conductivity and saturation vapor pressure have an increasing tendency with increasing volume concentration. However, surface tension and latent heat of vaporization showed a reverse tendency. Furthermore, the temperature also showed had obvious influence on the nanofluids viscosity, thermal conductivity and surface tension.
Au Nanowires Encapsulated in Carbon Nanotubes: Structure, Melting and Mechanical Properties
Authors: Wang Y. X. , Pan Z. Y. , Zhu B. E. , Xiao Y. , Guo S. H.
Published: June 2011

Classical molecular dynamics simulation was used to investigate the structure, melting and mechanical properties of Au nanowires encapsulated in single-walled carbon nanotubes (SWCNT). A possibility of synthesizing controlled Au nanowires was firstly studied by encapsulating small clusters into CNTs with suitable diameters. The nanowires with multi-shell structure of cylindrical symmetry are predicted as a consequence of spontaneous and confined coalescence of gold clusters. The investigation of melting temperature and behavior of a gold nanowire with multi-shells in a carbon nanotube (CNT) showed that the melting temperature of the enclosed Au nanowire is lower than its bulk counterpart and higher than that observed for free-standing ones. Different from the melting behavior of freestanding Au nanowires, the melting of Au nanowires enclosed in CNTs with tube diameters (D) in the range of 1.08 nm < D < 2.09 nm investigated here was found to initiate from the center layers. Finally, the deformation behavior of the gold-filled single-walled carbon nanotube was simulated under axial compression. The results show that the buckling strength of the Au-filled carbon nanotube is increased compared with that of a hollow tube, and is similar to the case of filling with gases or fullerenes. The interactions between filling elements and the carbon wall help restrain the collapse of the tube. With Au-filling, the filled tube experiences an elastic-inelastic transition, somewhat like the behavior of metals, which is different from the cases when it is filled with gases or fullerenes, particularly for low filling density.
Surface Nanostructure of Anealled 40Cr Steel by Supersonic Particles Bombarding Treatment
Authors: Liu Yu Liang , Xiong Tian Ying
Published: June 2011

A nanostructured layer can be introduced on the surface of metallic materials by surface severe plastic deformation. A surface severe plastic deformation method-Supersonic Particles Bombarding (SSPB) was used to treat the anealled 40Cr steel. The surface and cross sectional microstructure of 40Cr steel after SSPB treatment were characterized by means of X-ray diffraction, optical microscopy and transmission electron microscopy equipped with a Kikuchi line program to determine the grain orientations. Equiaxed nanocrystallites with random crystallographic orientation were obtained on the top surface of 40Cr steel after SSPB treatment. The surface microstructure was composed of nanostructure area, deformed area and matrix. Geometrically necessary boundaries and incidental dislocation boundaries were formed in the deformed ferrite at the distance to the surface of about 50-60μm, and the original coarse ferrite grain was divided into lamaller structure.