bluuebunny/crossref_metadata_2025 huggingface dataset:
The Study of Flower-Shaped Structure Dislocation in 4 Inch <100> Germanium Single Crystal
Authors: Li Miao Miao , Su Xiao Ping , Feng De Shen , Zuo Jian Long , Li Nan , Wang Xue Wu
Published: June 2011

As the key component of single junction GaAs/Ge solar cells and GaAs/Ge solar cells, the quality of germanium single crystal affects the properties of space solar cell directly. The dislocation of germanium single crystals is the main impact factor on solar cells efficiency. Through measuring dislocation densities in the different positions of 4 inch <100> germanium single crystals produced by Czochralski method, we found that flower-shaped structure dislocations pattern was mainly caused by the inclusions. This paper briefly analyzed dislocations produced by inclusions, chemical etching pits method. SEM and EDS measurement methods were also employed to study the flower-shaped structure defects. A germanium single crystal with low dislocation density was obtained and the special defects were almost eliminated. The germanium single crystal with low dislocation density (PV) was obtained, which could meet the requirement of the GaAs/Ge solar cells.
A Research on Energy-Saving and Environmental Impacts of Primary Magnesium and Magnesium Alloy Production in China
Authors: Gao Feng , Nie Zuo Ren , Wang Zhi Hong , Gong Xian Zheng , Zuo Tie Yong
Published: June 2011

China is the largest primary magnesium producer in the world, because of nearly 80% of the global market share. In the present paper, an approach of life cycle assessment (LCA) was applied to build an inventory of air emissions and to analyze the environmental impact of the global warming potential (GWP) and the acidification potential (AP) related to the production of AZ91D magnesium alloy. A summary of environmental impacts of primary magnesium and primary aluminum production with various studies was made to show the influence of uncertainties on the impacts. The results showed that the cumulative GWP and the acidification potential (AP) of AZ91D Mg-alloy are 33.4 t CO2eq/t ingot and 139 kg SO2eq/t ingot, with the range of 29.5-36.3 t CO2eq/t ingot and 104-152 kg SO2eq/t ingot, respectively. The GWP and AP of primary magnesium account for 90% and 77% of the cumulative environmental impact of AZ91D Mg-alloy. Under the grand background of advancing the development strategy of energy-saving and emission-reducing, China magnesium smelting and manufacture industry has made rapid progress in the structure optimization, energy efficiency improvement, and environment protection. The calculated data show that the improvement measures, e.g. reduction of dolomite consumption and energy consumption, in Chinese Pidgeon process led to 23% decrease of the GWP for the primary magnesium production in 2009 compared with 2005. The global warming reduction potential for 1 ton AZ91D alloy ingots produced in China was estimated of substituting HFC-134a for SF6as a cover gas.
The Influence of the Purity of Gd on the Magnetocaloric Effect in Gd5Si2-XGe2-XZn2x Alloys
Authors: Zeng Zhi , Wang Xue Zhen , Huang Jian , Xiang Jie , Hou Xue Ling
Published: June 2011

Gd5Si2Ge2-based alloys can exhibit a giant magnetocaloric effect (GMCE) which gives them the potential use in the cooling technologies[1].Through this studies, it can be found that the purity of Gd had a great impact on the magnetocaloric effect in Gd5Si2-xGe2-xZn2x alloys. When 3N Gd used and 2x=0.01, Gd5Si2-xGe2-xZn2x around the curie point of 280k get the maximum magnetic entropy change of 14.0 J/(Kg.K) under the external magnetic field change from 0 to 1T, but when 2N Gd used and 2x=0.05, Gd5Si2-xGe2-xZn2x around the curie point of 284.2k under the external magnetic field change 1T get the maximum magnetic entropy change 6.65 J/(Kg.K).
Effect of Hydroxyapatite Matrix on the Growth of Carbon Nanotubes via a CVD System
Authors: Lu Xiao Ying , Wu Bao Hua , Liu Yu Jie , Qiu Tian , Weng Jie
Published: June 2011

This paper reports the fabrication of carbon nanotubes (CNTs) /hydroxyapatite (HA) composites via in-situ process in a chemical vapor deposition (CVD) system and the effect of HA matrix on the growth of CNTs. When the HA matrix is fabricated by a chemical coprecipitation method, deficient HA (D-HA) crystals in nano size have been observed in these composites. There are about 20% weight percent of multi-walled CNTs with a mean diameter of 40~60 nm. When the matrix used as catalyst for CNTs growth without HA in the same way, no CNTs but solid carbon fibers in submicrometer scale have been produced in these composites. Only Fe and MgO crystals can be observed in these composites. When the HA matrix is fabricated by a physical mixing with the presence of D-HA crystals, hollow CNTs with the diameter of 180~210 nm are also produced in these composites. Fe and MgO besides P2O5, D-HA and C crystals can be observed in the composites.
Inhibitory Effect of Hydroxyapatite Nanoparticles on K562 Cells
Authors: Dai Hong Lian , Chen Pei , Han Yin Chao , Wang Xin Yu , Li Shi Pu
Published: June 2011

HAP Nanoparticles Was Synthesized by Homogeneous Precipitation. the Size Distribution, Crystallization Degree and Morphology of the Precipitation Were Characterized by Laser Granularity Instrument, X-Ray Diffraction (XRD), and Transmission Electron Microscope (TEM) Respectively. the Prepared HAP Nanoparticles Were Used for the Treatment of Human Chronic Myeloid Leukemia K562 Cells. the Inhibition Effect of the Nanoparticles on the Proliferation of K562 Cells Was Measured by MTT Assay and Growth Curve Test. the Results Showed that the HAP Nanoparticles Inhibit the Proliferation of K562 Cells Dramatically in Vitro. the Likely Inhibition Mechanism of HAP Nanoparticles on the K562 Cells Is that the Nanoparticles Entered into the Dells, Induced a Series of Cell Changes, through Cell Death of Apoptosis, Oncosis and Autoschizis, Thus Led to the Death of K562 Cells.
Modification of Pearl Surface Microstructure by Rare Earth Cerium Induced Growing
Authors: Shi Wei Lin , Ma Xi Ying
Published: June 2011

The beautiful luster of freshwater pearls is closely related to its multiplayer microstructure. We present the improvement of their luster by refinement their superficial microstructure of pearls by rare earth cerium (REE) inducing grown. The pearls were cultured in freshwater containing 0 (control group), 0.5, and 1 mg·L-1 REE Ce additive, respectively. As the concentration of Ce in the aqueous increasing, we find that their superficial microstructure take large change. The shape of the blocks that builds up the microstructure changes from anomalous to round discs, and finally to perfect regular square sheets. Correspondingly, the glossiness of the pearls changed with the microstructure, in which the pearls with the regular hexagonal blocks having the highest glossiness.
Strontium-Borosilicate-Co-Effects to Stimulate Bone Regeneration
Authors: Shen Yu Hui , Zhang Kui Bo , Pan Hao Bo , Lu William W. , Zheng Zhao Min , Wang De Ping , Deng Lian Fu , Zhou Nai , Huang Wen Hai
Published: June 2011

As a naturally-occurring trace element, boron involves many life processes including embryogenesis, bone growth and maintenance, immune function and psychomotor skills. Thus, the low chemical durable glass based on 3-fold coordination boron network former shows potential in delivering boron for bone health. However, its high dissolution rate may result in cytotoxicity. The addition of strontium seems to be an effective approach not only inhibits its rapid degradation, but delivers strontium as a ‘drug’ to enhance the ability of bone formation. Thus, strontium-incorporated borosilicate shows special role in bone regeneration, in particular in women past menopause.
Improved Gel Electrolyte by Layered α-Zirconium Phosphate for Quasi-Solid-State Dye-Sensitized Solar Cells
Authors: Han Liu , Wang Ning , He H.C. , Kong D.T. , Chen H.J.
Published: June 2011

In this article, we present a new composite gel electrolyte for dye-sensitized solar cells (DSSC), with butylamine (BA) and propylene carbonate (PC) intercalated α-Zirconium phosphate (ZrP-BA-PC) as solid fillers dispersed in polyethlene oxide (PEO) polymer. The ionic electrical conductivity was markedly improved with the ZrP-BA-PC additive at ambient temperature. The DSSC with 5 wt% ZrP addition into the electrolyte obtained the maximum photovoltaic conversion efficiency of 6.61 % under 100 mW/cm-2irradiation.
Influence of Polymer Concentration on Polysaccharide Electrolyte for Quasi-Solid-State Dye-Sensitized Solar Cell
Authors: Yang Ying , Guo Xue Yi , Zhao Xing Zhong
Published: June 2011

A series of polymer electrolytes was synthesized to fabricate dye-sensitized solar cells by a novel polysaccharide agarose as polymer matrix, 1-methyl-2-pyrrolidinone (NMP) as plasticizers, lithium iodide (LiI)/iodine (I2) as redox couple and titania nanoparticles as an absorber. The agarose polymer electrolytes with different agarose concentrations (1-5 wt %) were systematically studied by differential scanning calorimetry (DSC) and the AC impedance spectra. The photoelectric performances of the DSSCs with different agarose content were investigated. Increasing polymer concentration led to a decrease in Tg of electrolyte in the low content range (1-2 wt %), which results in relative high conductivity in these content ranges. The 1.5 wt % agarose contained electrolyte showed the maximum conductivity of 3.94 ×10-4 S cm-1. After optimization, the energy conversion efficiency of 4.14 % was obtained in the cell with 2 wt % agarose.
Mechanism of Blue Shift of Optical Band Gap in Aluminum-Doped ZnO Thin Films with Blend Bond
Authors: Shen Ling , Shen Cheng , Yang Jie , Xu Fei , Ma Zhong Quan
Published: June 2011

In this paper, aluminum–doped nano-crystalline zinc oxide (ZnO:Al or AZO) thin films were deposited on fused quartz substrate by pulsed laser ablation at various temperatures. The physical phase and surface morphology were characterized by using X-ray diffraction (XRD) and atomic force microscope (AFM), respectively. The variation of the optical band gap (Egopt) of the films with the temperature was measured through transmittance in UV-VIS wavelength. The results showed that there was a blue shift of Egoptfrom 3.44 eV to 3.62 eV as the growing temperature decreased from 500°C to 200°C. The value of Egoptimmediately recurred from 3.30 to 3.35 eV after a thermal annealing of the samples at 700 °C, inclining to a normal value of bulk zinc oxide. The analyses of XRD and AFM testified that the presence of amorphous phase in the AZO films was the main reason for the blue shift of the optical band gap Egopt.
Effects of Gallium Addition on the Microstructure and Electrochemical Properties of Al-Zn-Bi Series Alloy Anode
Authors: Hao Qing Guo , Wen Jiu Ba , He Jun Guang , Ma Jing Ling
Published: June 2011

The open circuit potential, working potential and current efficiency of Al-5Zn-0.5Bi and Al-5Zn-0.5Bi-0.015Ga alloys in artificial seawater were tested by constant current method. The corrosion characteristics of the anode alloys in 3.5% NaCl solution were studied by polarization curves and electrochemical impedance spectra. The surface corrosion morphology and microstructures of the alloys were observed and investigated by metallographic microscopy, scanning electron microscopy and X-ray energy dispersive analysis. The results show that the open circuit potential shifts towards negative, working potential becomes stable and the current efficiency becomes high through the addition of gallium in the alloy. Gallium can be uniformly dissolved in aluminum alloy and effectively reduce the segregation of Bi. The cations can deposit back to the anode surface forming into the Ga-Al amalgam, which promotes its homogeneous dissolution and improve comprehensive electrochemical performance.
Corrosion Performance Study of Anodic Film Formed by Oxidizing Magnesium Alloy in Environmentally Friendly Electrolyte
Authors: Zhang Ding Fei , Cui Li Bo , Liu Yu Ping
Published: June 2011

The effect of different factors on the corrosion performance of the anodic ﬁlm formed on AZ31 was studied by using electrochemical impedance spectroscopy (EIS) and Tafel polarization curves techniques. The result of EIS showed that the oxide film formed at 20 mA·cm-2 had the highest corrosion resistance and the optimum temperature was 40°C. The similar conclusion was drawn by the Tafel polarization curves. Moreover, the equivalent electrical circuit R(C(R (QR))) (CR) was used to analyze the EIS data.
Influence of Cl- on Corrosion Behavior of AZ91 Magnesium Alloy in Simulating Acid Rain
Authors: Zhou Wan Qiu , Tang Wei , Shan Da Yong , Han En-Hou , Ke Wei
Published: June 2011

Initial corrosion behavior of AZ91 magnesium alloy in simulating acid rain containing Cl- is investigated by SEM/EDX and electrochemical method. The results show that corrosion of magnesium alloy in diluted NaCl solution was localized corrosion, and the attack only occurred around the scattered AlMn particle which induced the departure of AlMn from metal matrix. HSO3- in acid rain induced the dissolution of corrosion in α phase, β phase was not be corroded and presented in passive state. The corrosion of magnesium alloy in simulating acid rain containing Cl- was mainly induced by HSO3-, and the existence of Cl- accelerated the corrosion process.
Laser Cladding of Ni-Based Alloy on Mg Alloy with Brass Transition
Authors: He Qing Kun , Cui Hongzhi , Huang Shao Hua , Sun Jin Quan , Yang Hong Guang , Li Yong Feng
Published: June 2011

Laser cladding of Ni-based alloy on Mg-alloy was achieved by using brass as transition layer on substrate. The Ni-based alloy layer free of cracks and porosities was bonded metallurgically with the Mg substrate using brass as the transitional layer. The Ni-based cladding layer was mainly composed of Cr2Ni3, FeNi3, AlNi3 while the content of Mg, Al, Cu and Zn is very low in the cladding layer. Microhardness and the wear resistance of the sample were tested, whose results indicated that microhardness and wear resistance increased 12.8 times and 13.3 times, respectively compared with the substrate. In addition, the corrosion potential (Ecorr) of the sample was much higher than that of untreated materials.
Mechanical Behaviors of Magnesium Alloy AZ61 under Different Strain Rates and Heating Rates
Authors: Chen Bin , Yuan Quan , Luo Ji , Zhang Ding Fei , Quan Guo Zheng
Published: June 2011

The effects of strain rate (SR) and heating rate (HR) on the mechanical behaviors of the tensile specimens of magnesium alloy AZ61 were experimentally investigated using a Gleeble-1500 thermal-mechanical material testing system. It showed that the higher the temperature is, the lower the ultimate strength of the specimens will be. The higher the heating rate is, the higher the ultimate strength of the specimens will be. The metallurgraphs of the fracture section of the specimens were also experimentally investigated for exploring their failure mechanism under different temperatures and heating rates. It showed that the high temperatures and high heating rates will induce microvoids in the specimens. The microvoids make the specimens failure under relative low loads.
Microstructure and Corrosion Resistance of AM60 Magnesium Alloy Modified by Plasma Surface Treatment
Authors: Cui Hongzhi , Sun Jin Quan , Xiao Cheng Zhu , Yang Hong Guang
Published: June 2011

Fine single solid solution α-Mg phases with an average grain size of less than 5 um was obtained in the melting layer of the surface of AM60 Mg alloy by means of plasma beam treatment. The influence of the plasma parameter on both the melting depth and the grain size was discussed. The microstructure, morphology and corrosion properties of the melting layer were analyzed by optical microscopy (OP), scanning electron microscopy (SEM), simulated corrosion test, respectively. The micro-hardness of the melting layer is up to 200 HV0.05 by means of environment-friendly plasma surface treatment and the corrosion resistance of AM60 magnesium alloy was greatly improved.
Direct Chill Casting of Φ500mm ZK60 Magnesium Alloy Billets under Low Frequency Electromagnetic Field
Authors: Zhang Zhi Qiang , Le Qi Chi , Cui Jian Zhong
Published: June 2011

Effects of low frequency electromagnetic field on surface quality, microstructure and hot-tearing tendency of direct chill casting of Φ500mm ZK60 magnesium alloy billets were investigated. The results show that with the application of the low frequency electromagnetic field, the surface quality of Φ500mm ZK60 magnesium alloy billets has been markedly improved, and the depth of cold fold is decreased. In the conventional direct chill casting, the microstructures of the billet, especially at the center, are coarse. The distribution of the grain size is non-uniform throughout the billet. From the edge to the center, the microstructure gradually changes from fine to coarse in all billets. However, under the low frequency electromagnetic casting, the microstructures of the billet is significantly refined, the distribution of the grains size is relatively uniform from the billets edge to the billets center. And it also shows that the hot-tearing tendency of direct chill casting Φ500mm ZK60 magnesium alloy billets under low frequency electromagnetic field is significantly reduced.
Solute Distribution and Segregation during Solidification of Mg-6Al Alloys
Authors: Wu Yu , Pan Fu Sheng , Jiang Bin , Li Xiao Ke , Fu Qi Tao
Published: June 2011

Solute distribution and segregation in solidification will largely influence the characteristics of solidification microstructure and precipitation order of the second phase. In this paper, the solid-liquid interfaces of Mg-6Al alloy with different temperature were obtained by rapid quenching based on a special melting furnace and were analyzed using scanning electron microscopy, energy diffraction spectrum and Thermo-Calc calculation tool. It was found that the primary α-Mg phase grew through cystiform dendrite interface. The solute partition coefficient and dendrite segregation rate for Al in the solid phase of Mg-6Al alloy basically had little change with decrease of the temperature. The dendrite become fine, and the solute partition coefficient decreased, while dendrite segregation rate of Al in the dendrite boundaries increased, because of the addition of Zn to Mg-6Al alloys.
Influence of Forward Extrusion on the Mechanical Properties and Microstructure of Homogenized AZ80 Magnesium Alloy
Authors: Li Yong , Zhang Zhi Min , Xue Yong , Li Li
Published: June 2011

The forward extrusion experiments of homogenized AZ80 magnesium alloy were conducted in the extrusion temperature range of 300°C to 420°C and extrusion ratios between 15 and 75 to study the effect of plastic deformation on the mechanical properties and microstructure. The microstructure and mechanical properties of extrudate were measured by tensile tests and optical microscopy. The results demonstrated that the alloy grains were small, and small amounts of black hard and brittle second-phase precipitated at 330°C. When the extrusion temperature was up to 390°C, the grain size increased significantly, but the second phase precipitation became continuous. And then, in the case of the extrusion ratio of 60, the tensile strength of the alloy reached the peak value of 390 MPa. Inhomogeneous precipitation of the second-phase increased with the increasing of extrusion temperature. At the same temperature, the tensile strength increased firstly and then decreased with increasing extrusion ratio. With the gradual increase of the grain refinement, the dispersed precipitates increased and the tensile strength and plasticity reached their peaks when the extrusion temperature was 390°C. As the grain grew, the second phase distribution became inhomogeneous, and the strength and plasticity gradually decreased.
A Simplified Method of Synthesis and Purification of 4-Dimethylamino-N-Methyl -4-Stilbazolium Tosylate
Authors: You Fei , Sun Jin , Teng Bing , Xia Lin Hua , Jiang Xin Xing , Xu Hui , Zhong De Gao , Rupp Romano A
Published: June 2011

DAST (4-dimethylamino-N-methyl-4-stilbazolium tosylate) crystal material was synthesized and purified by a relatively simple method. The synthesis process was easy to operate experimentally and the cost of raw materials can be cut down. The purification process was much easier than the previously published method. Fourier transform infrared spectrum (FTIR) was used to analyze the functional group of raw material and no extra functional groups were found. Nuclear magnetic resonance (NMR) study was performed to identify the different modes presented in the compound. The results showed that the quality of the prepared crystal raw material could meet the requirements on crystal growth. DAST crystals were grown from the synthesized raw material by slowly cooling method. The crystal structure was characterized by X-ray diffraction (XRD) study and the results showed that the crystal grown from the synthesized raw material was the same as that grown from pure DAST crystal raw material.
Fabrication and Properties of Cf/SiC Composites Derived from Polysiloxane Precursor
Authors: Xu Tian Heng , Ma Qing Song , Chen Zhao Hui
Published: June 2011

Carbon fiber reinforced silicon carbide composites (Cf/SiC) were derived through precursor infiltration pyrolysis route (PIP) at 1600°C in vacuum atmosphere using polysiloxane as precursor. The matrix of Cf/SiC was characterized by X-ray diffraction and elemental analysis. The results show that crystalline β-SiC can be derived at 1600°C in vacuum from polysiloxane. The flexural strength and fracture toughness of polysiloxane derived from Cf/SiC can reach up to 70 MPa and 2.3MPa·m respectively1/2.
Model and Maximal Pull-Out Force of Helicoidal Fiber Structure in the Underpinnings of Tumblebug Cuticle
Authors: Chen Bin , Yin Da Gang , Yuan Quan , Luo Ji , Fan Jing Hong
Published: June 2011

The observation of scanning electron microscope (SEM) on the cuticle of Tumblebug shows that the cuticle is a kind of biocomposite consisting of chitin-fibers and collagen protein matrix. The observation also shows that there are many underpinnings in the cuticle. The underpinnings are also a kind of biological composite consisting of chitin-fiber layers and collagen protein matrixes. More careful observation indicates that the chitin-fiber layers enwrap the core of the underpinnings forming a kind of helicoidal fiber structure. The maximal pull-out force of the helicoidal fiber structure, related to the fracture toughness of the underpinnings, is theoretically and experimentally investigated and compared with that of parallel fiber structure. It shows that the maximal pull-out force of the helicoidal fiber structure is larger than that of the parallel fiber structure, which gives profitable information for the design of man-made high-performance composites and composite structures.
Preparation of CNTs/PANi Core/Shell-Structured Nanowires and Improvement of Sensitivity of Chemical Sensors
Authors: Ma Xing Fa , Niu Shu Juan , Gao Ming Jun , He Xiao Chun , Li Guang
Published: June 2011

In order to improve the sensing-properties of carbon nanotube based composite for potential applications in chemical sensors, CNTs/PANi core/shell-structured nanowires were prepared with in-situ polymerization approach. A series of characterizations was carried out by TEM (transmission electron microscopy), the Fourier-Transform Infrared (FTIR) spectra, and so on. A chemical prototype sensor was constructed based on CNTs/PANi core/shell-structured nanowires and interdigital-structured electrodes on flexible polymer substrate. The gas-sensing behaviors of the sensor to some gases operating at room temperature were examined. Results showed that the sensitivity of CNTs/PANi core/shell-structured nanowires was increased dramaticly compared with pure carbon nanotube materials. This provides a carbon nanotube based composite materials with enhanced gas-sensitivity, which would have potential applications in some chemical sensors.
Effect of Composite Energy-Field on Microstructure and Properties of AZ31B Magnesium Roll-Casting Alloy Sheet
Authors: Mao Da Heng , Zhao Guan Zhong , Li Jian Ping , Hu Jian Bing , Zhang Sheng Fang
Published: June 2011

With composite energy-field of ultrasonic field and electromagnetic field introduced into the roll-casting process，AZ31B magnesium alloy has been acquired successfully，during this process，the effect of composite field on structure and properties of AZ31B magnesium roll-casting alloy are studied. The result shows that the composite field can decrease the grain size greatly from 60-80μm to 12-18μm compared with the conventional roll-casting(without out-field), improving the tensile strength and yield strength by 13% and 35% respectively and the elongation increased by 82.2%（average value）.Meanwhile，the microstructure of magnesium alloy obtained with the composite field are more uniform after annealing，mechanical properties are improved greatly as well.
Synthesis of (3-Mercaptopropyl)Trimethoxysilane-Modified ZMS and Study of the Enhancement of Ammonia-Nitrogen Removal from Water
Authors: Zhu Peng , Hu Li Jiang , Wang Di , Zhang Qun , Song Sheng Yao
Published: June 2011

In this work, the mesoporous zeolite molecular sieve (ZMS, SBA-15) was prepared by rice hull ash (RHA) and the surface of ZMS pore was modified by (3-mercaptopropyl) trimethoxysilane (MCPMS) with sulfhydryl (SH) as active group connecting to the SBA-15 pore surface. The capacity of removing ammonia-nitrogen (NH3-N) in water will be increased because of the increasing in adsorption active groups. The micro-structures of SBA-15-SH were characterized by FTIR, SEM, TEM, SAXRD. The diffusion and adsorbed behavior of NH3-N in pores of the modified ZMS was simulate by using a molecular dynamic simulation (MDS) program of the Materials Studio software (MSS) which facilitated study of the effect of this modification on pore structure and adsorption capacity. As results of the experiments, the MCPMS-modified ZMS showed more efficient in removing NH3-N in drinking water than before the modification under the same conditions.
Evaluation of Burnished Subsurface Mechanical Behavior Using Nanoindentation
Authors: Luo Hong Yun , Han Zhi Yuan , Zhong Qun Peng
Published: June 2011

The performance and life of machined components in service are mainly effect by their surface integrity. Burnishing process is a kind of chipless processing which improve the surface integrity obviously. A subsurface “hardness film” is formed during the processing. Subsurface mechanical behavior is the main part of surface integrity. Since the very small scale of the subsurface in burnished surface nanoindentation is used to identify how the local changes of microstructure influence the hardness distributions of subsurface mechanical properties. This study focuses on the relationships between burnishing parameters (burnishing feed and burnishing depth) and nanohardness. A series of burnishing processing experiments and nanoindentation tests were conducted on the surface of the burnished samples. The microstructure and nanoindentation research results indicate that there is no visible phase transformed region in the subsurface of burnished specimens, the hardening film is larger than 4 micro meters, the nanohardness is about 2.2~3.5Gpa which depends on the burnishing parameters and distribution and position of the second phase particles, while the nanohardness in turned material is about 1.8Gpa.
Microstructure and Oxidation Behavior of Molybdenum Disilicide Coating Prepared by Air Plasma Sprayed
Authors: Yan Jian Hui , Tang Si Wen , Xu Jian Guang
Published: June 2011

Intermetallics molybdenum dislicied has a great potential as a protective coating in aircraft engines and gas turbines in the elevated temperature. The suit for plasma spraying MoSi2 powders were prepared by spray drying process and vacuum sintered. The oxidation behaviors of the coating were determined at 1200 °C. The coatings as sprayed and oxidized were characterized by XRD, SEM and EDS. Results show that the flow ability and loose density of MoSi2 powder by sintered treatment, were 17.1 s/50g and 2.1g/cm3, respectively, ideal for air plasma spraying. During the course of spraying, some of molybdenum disilicide with a tetragonal lattice was converted into molybdenum disilicide with a hexagonal lattice. Also, part of MoSi2 phase oxidized and transformed to Mo5Si3 phase. A relative dense molybdenum disilicide coating was prepared by air plasma spraying. A protective SiO2 layer, seems to be glassy, with a thickness about 10 μm was formed on the surface of MoSi2 coating during MoSi2 coating oxidized at 1200°C for 200 h. The results of the oxidation tests show that MoSi2 coating prepared by air plasma spraying may be provide a protect layer for high temperature structure material.
Si-B Co-Deposition Coatings on an Nb Silicide Based Ultrahigh Temperature Alloy Prepared by Pack Cementation Technique
Authors: Zhang Yu , Guo Xi Ping
Published: June 2011

In order to improve the oxidation resistance of silicide coatings on an Nb silicide based alloy, Si-B co-deposition coatings were prepared at 1150°C for 8 h by using pack mixtures containing different amounts of B powders. The microstructural characteristics of the coatings were studied. The results showed that all coatings had a triple-layer structure. The middle layers of all coatings were composed of (Nb,X)Si2 (X represents Ti, Cr and Hf elements) and the inner layers of all coatings were composed of (Nb,X)5Si3, but the outer layers of the coatings had different phase constituents and morphologies when the amount of B powders in the pack mixture changed. When the amount of B powders in the pack mixture ranged from 0.5 wt% to 12 wt%, the outer layers were composed of (Nb,X)B2­, with a few CrB2 particles. When the amount of B powders in the pack mixture was in the range of 0.05~0.1 wt%, the outer layers were composed of (Nb,X)B2. However, when the amount of B powders in the pack mixture was in the range of 0.02~0.03 wt%, the outer layers were composed of (Nb,X)Si2, with needle-like (Nb,X)B2 particles dispersed in it.
Influence of Boron Nitride on Tribological Behavior of Nickel-Base Composite Coatings at High Temperature
Authors: Zhang Yong Kang , Li Jian Liang , Xiong Dang Sheng , Qin Yong Kun
Published: June 2011

The nickel-based boron nitride composite coatings were prepared by reversing pulse electro-deposition. The mechanical properties and friction behavior of the coatings at high temperature were tested by using Al2O3 ceramic ball at high temperature friction-testing machine. The results show that the surface micro-hardness of the coatings increases with the addition of BN powder. Meanwhile, the friction coefficient and wear rate of specimens decreases. Especially when the BN addition is 1.5g/L the composite coatings present a minimum of friction coefficient and wear rate. In optimum process parameters, the friction coefficient of the coatings is about 0.2 at room temperature and 0.4-0.5 at 600°C. In addition, the friction and wear properties were significantly improved by plating Ni transition layer plated between substrate and composite coating.
Enhanced Saturation Magnetization of Nanocrystalline Cobalt Produced by Surface Mechanical Attrition Treatment
Authors: Li Wei , Liu Ping , Ma Feng Cang , Liu Xin Kuan , Chen Xiao Hong , Rong Yong Hua
Published: June 2011

A nanocrystalline surface layer is produced in Co plate by surface mechanical attrition treatment (SMAT). The characterization of microstructure and composition indicates that elements of Fe, Cr diffuse from hardened steel balls into the surface layer during SMAT. The diffusion phenomenon results in the composition deviation in the surface layer, leading to higher value of saturation magnetization(Ms) for nanocrystalline Co surface layer in comparison with its coarse-grained counterpart.
Effect of Melt Superheating Treatment on the Microstructure of as Cast AZ61 Magnesium Alloy
Authors: Peng Jian , Tao Jian Quan , Fan Shi Bo , Pan Fu Sheng
Published: June 2011

The influence of melt superheating treatment on microstructure of as cast AZ61 magnesium alloy was investigated at the melt superheating temperatures of 750°C, 800°C, 850°C, 900°C and 950°C respectively. The characteristics of dendrite spacing were analyzed and the component uniformity of the alloy was evaluated. The results showed that the melt superheating treatment could significantly refine the microstructure of the alloy. With the increase of the superheating temperature, the dendrite spacing gradually decreased. When the superheating temperature was 900°C, the primary dendrite spacing of 228.8μm and the secondary dendrite arm spacing of 11.2μm could be obtained. The concentrations of Al and Zn elements increased with the position change from the center of a dendrite to its primary dendrite spacing. With the increase of the superheating temperature, the distribution of Zn and Al in the alloy was more uniform under 850°C. The optimized superheating temperature of AZ61 alloy was 850-900°C.
Effect of Structure on the Mechanical Properties of PAN-Based Carbon Fibers during Graphitization
Authors: Xiao Hao , Lu Yong Gen , Qin Xian Ying , Wen Ya
Published: June 2011

An investigation was conducted to determine the influence of high temperature treatment from 1600°C to 2800°C under stretching stress of 10MPa on PAN-based carbon fiber structure and physical properties. The tensile strength of fibers decreased from 4.5GPa to 2.97GPa with increasing treatment temperature up to 2800°C，while the modulus of fibers increased from 230GPa to 375GPa The texture in the longitudinal surface of fibers through heat treatment was characterized using a scanning electron microscopy. The contours of fiber surface became accidented with gaps becoming deeper as temperature increased. It has been observed that both the crystallite sizes (La, Lc) and the degree of preferred orientation increasd, while the crystallite interlayer spacing (d002) decreased by X-ray diffraction analysis with increasing heat-treatment temperature. The total porosity of fibers decreased from 21.01% to 15.09% and while the density of fibers increased from 1.720g/cm-3 to1.886 g/cm-3 with increasing heat-treatment. In addition, the relationship between mechanical properties and structure of variants was also explored in detail.
Preparation of Polyacrylonitrile High Modulus Carbon Fibers by Catalytic Graphitization Using Boron
Authors: Wen Ya , Lu Yong Gen , Qin Xian Ying , Xiao Hao
Published: June 2011

Catalytic graphitization of polyacrylonitrile-based carbon fiber by doping boric acid was reported in this paper. The microstructure and mechanical properties of polyacrylonitrile-based carbon fibers with and without doping boric acid after heat treatment of 1300°C,1500°C,1800°C, 2100°C,2300°C,2400°Cand 2500°Cwas investigated by X-ray diffraction (XRD) and mechanical testing. The results showed that the tensile modulus of the carbon fibers either boron modified or not, increased obviously with increasing temperatures, and that of the modified carbon fibers was much higher than the unmodified fibers at all temperatures, reaching 404Gpa when the fiber was graphitized at 2500°C. The tensile strength of the modified carbon fibers was lower than the unmodified ones after being graphitized at temperatures below 2300°C, but increased to 2.69 GPa and 2.46 GPa respectively after the fibers were treated at 2300°C and 2500°C, which were higher than that of unmodified fibers treated under the same conditions, indicatinging that the mechanism of boron catalytic graphitization changed at the temperatures higher than 2300°C. It also showed that the interlayer spacing (d002) decreased, while the crystallite size (Lc) and the orientation increased with increasing temperatures.
Research and Classification of Inflatable Space Vehicle and its Materials
Authors: Liu Dong Xu , Liu Long Bin , Meng Jun Hui
Published: June 2011

Inflatable space vehicle (ISV) has a variety of advantages of light mass, volume changeability and low cost, and becomes the hotspot in space vehicle research recently. But most researchers concentrate their efforts on applications of ISV in their dedicated domains, and the holistic viewpoint of ISV is indistinct. In this paper, the new developing space vehicle, ISV is classified into flatness, lenticula, sphere and cabin in brief due to its different structures and applications. Each type owns its special materials for folding, inflation-deployment, rigidization and resistibility in the space rigorous environment. Materials utilized in typical ISV are summarized subsequently, which can be sorted by polymer films, flexible rigidizable composites and multiple-layer laminates. Finally, the properties of ISV materials including environment endurance, mechanics, fabrication technologies and special functions are concluded, which is useful in material design and optimization.
Influence of SiO2 Layer on Resistive Switching Properties of SiO2/CuXO Stack Structure
Authors: Liu Chih Yi , Li Yu Chen , Lai Chun Hung , Liu Shih Kun
Published: June 2011

CuxO and SiO2thin films were deposited using a radio-frequency magnetron sputter on Pt/Ti/SiO2/Si substrates to form SiO2/CuxO/Pt and CuxO/Pt structures. The current-voltage characteristics were measured by DC voltage sweeping using a tungsten (W) probe. The two structures needed a large voltage to initiate the first resistive switching; this sweep was called the forming process. Afterwards, the resistances of the two structures could be switched reversibly between the low-resistance-state (LRS) and high-resistance-state (HRS) by applying a DC voltage. The conduction mechanisms of the LRS and the HRS were dominated by Ohmic conduction. Structures with non-destructive readout characteristics and long retention time were suitable for use in non-volatile memory. The difference between resistive switching in W-probe/SiO2/CuxO/Pt and W-probe/CuxO/Pt structures was investigated. The additional SiO2layer decreased the switching voltages and currents; this should be due to the presence of pinholes within the SiO2layer. The influence of SiO2thickness on the resistive switching characteristics was also investigated. The switching voltages and currents, except the forming voltage, decreased as the thickness of SiO2decreased. The conducting filament model with a thermochemical reaction was suggested to best explain the resistive switching behavior that was observed.
Magnetic and Magneto-Optical Properties of Sputtered Co-CeO2 Thin Films on Al2O3 (0001) Substrates with (100) Orientation
Authors: Song Yuan Qiang , Zhang Huai Wu , Liu Ying Li , Li Yuan Xun , Wen Qi Ye
Published: June 2011

Diluted magnetically doped CeO2 films is an attractive dilute magnetic oxide which would facilitate the practical realization of spintronic devices and may also be used to explore novel magneto-optical applications. In this experiments, 3 at% cobalt-doped CeO2 films with the stoichiometry of Ce0.97Co0.03O2-δ (CCO) were deposited by magnetron sputtering methods on Al2O3 (0001) substrates. The structural, magnetic, and magneto-optical properties were investigated. The results indicate that CCO films with CeO2 (100) orientation can readily be obtained via magnetron sputtering on Al2O3 (0001) substrates. Films are ferromagnetic at room temperature, which is anisotropic with an out-of-plane magnetization easy axis. Magneto-optical measurements exhibit a giant Faraday rotation of about 4800 deg/cm at 650 nm wavelength in out-of-plane direction. The excellent room-temperature ferromagnetism and the giant Faraday rotation in CCO films show highly potential applications in novel magneto-optical devices as well as in spintronics.
Preparation of the Carbon Nanotube / Carbon Fiber Composite and Application as the Electrode Material of the Electrochemical Super Capacitor
Authors: Jiang Qi , Yang Rong , Fu Guang Gang , Xie De Yu , Huang Bin , He Zheng Wen , Zhao Yong
Published: June 2011

Carbon nanotube (CNT) / carbon fiber (CF) composite was prepared by growing CNT in situ on the CF surface with catalytic chemical vapor deposition. The morphology of the obtained composite was characterized by the scanning electron microscopy. The results show that the CNT is trimly and equably grown on the CF surface. The obtained CNT/CF composite is covered with a layer of nickel (Ni) as a current collection on one side of the composite through the spray method. Then, the obtained materials were assembled to electrochemical super capacitors to characterize their electrochemical performances. The results show that the specific capacitance of the composite could be up to 105.4 F•g-1(organic electrolyte), which is much higher than those of the pure CNT and the CF (about 25.0 and 62.2F•g-1, respectively). These experimental results show that CNT grown in situ on the CF surface is a simple and feasible method to enhance the composite electrochemical performances.
Effect of Nb2O5 Addition on the Electrical and Physical Properties of Lead-Free 0.98(Na0.5K0.5)NbO3-0.02(Na0.5Bi0.5)TiO3 Piezoelectric Ceramics
Authors: Wang Chun Huy
Published: June 2011

In this paper, the effects of Nb2O5addition on the electrical and physical properties of 0.98(Na0.5K0.5)NbO3-0.02(Na0.5Bi0.5)TiO3were investigated. The 0.98(Na0.5K0.5)NbO3-0.02(Na0.5Bi0.5)TiO3[0.98NKN-0.02NBT] ceramics with the addition of 0~1.5 wt% Nb2O5have been prepared following the conventional mixed oxide process. X-ray diffraction analysis revealed that, during sintering, all of the (Na0.5Bi0.5)TiO3diffuse into the lattice of (Na0.5K0.5)NbO3to form a solid solution, in which an orthorhombic phase with a perovskite structure was found. For 0.98NKN-0.02NBT ceramics by doping 0.3 wt% Nb2O5, the poled dielectric constant (K33T) is 1180. The electromechanical coupling coefficients of the planar modekpand the thickness modektreach 0.43 and 0.52, respectively. Our results show that 0.98NKN-0.02NBT with the addition of 0.3 wt% Nb2O5is a good lead-free piezoelectric ceramic.
Molten Salt Synthesis of Anisotropy BaBi4Ti4O15 Powders in K2SO4-Na2SO4 Flux
Authors: Gu Yong Jun , Huang Jin Liang , Li Li Hua , Zhang Ke , Wang Xiao , Li Qian , Tan Xiao Hua , Xu Hui
Published: June 2011

Anisotropic BaBi4Ti4O15 powder was synthesized by a molten salt synthesis (MSS) method in K2SO4-Na2SO4flux and the effects of different process parameters such as calcining temperature, and ratio of salt to reactant (R) on the phase formation and morphology of anisotropic BaBi4Ti4O15particles were also investigated. The as-synthesized powder calcined at 850-950°C exhibits a single tetragonal BaBi4Ti4O15phase. The morphology of BaBi4Ti4O15powder could be adjusted by changing the synthesis conditions. The average particle size (APS) of BaBi4Ti4O15powder increased with R changing from 0.8 to 1.0, while it decreased with further increasing of R to 1.2. In addition, the APS increased with increasing calcining temperature and it showed an Arrhenius dependence on the temperature. The corresponding apparent activation energy for particle growth is 31.9kJ/mol for calcining temperature of 850-1000°C.
Performance Analysis of the 1-3 Piezoelectric Composites and Transducer Fabrication
Authors: Sun Min , Xu Dong Yu , Huang Shi Feng
Published: June 2011

1-3 polymer-based piezoelectric composites were fabricated using epoxy as the matrix by the cut-filling method. The influences of PMN volume fraction on the piezoelectric and dielectric properties of the composite were analyzed, and then the piezoelectric composite was fabricated to transducer whose properties were also analyzed. The results indicate that with increasing the PMN volume fraction, both the hydrostatic piezoelectric voltage gh and hydrostatic figures of merit dh·gh of the composite decrease, while the relative dielectric constant εr increases. The hydrostatic piezoelectric strain dh has the optimum value in the PMN volume fraction range of 40%-60%. The resonant frequency of transducer in water is 306.5 kHz and anti-resonant frequency is 352.6 kHz.
Physical and Electrical Properties of Lead-Free (Bi0.5Na0.5)TiO3-(Na0.5K0.5)NbO3 Ceramics
Authors: Wang Chun Huy
Published: June 2011

Lead-free (1-x)(Bi0.5Na0.5)TiO3–x(Na0.5K0.5)NbO3(x<0.1) ceramics have been prepared by the conventional mixed oxide process. X-ray diffraction analysis revealed that, during sintering, all of the (Na0.5K0.5)NbO3diffuse into the lattice of (Bi0.5Na0.5)TiO3to form a solid solution and the hexagonal phase with a perovskite structure. The samples with a low content of (Na0.5K0.5) NbO3exhibit relatively good physical and electrical properties. For 0.96(Bi0.5Na0.5) TiO3–0.04 (Na0.5K0.5) NbO3ceramics, the electromechanical coupling coefficients of the planar modekpand the thickness modektreach 0.25 and 0.52, respectively, after sintering at 1100 °C for 5 h. The ratio of the thickness coupling coefficient to the planar coupling coefficient is 2.08. With suitable (Na0.5K0.5)NbO3concentration and sintering conditions, a dense microstructure and good electrical properties are obtained. Our results show that 0.96(Bi0.5Na0.5)TiO3–0.04(Na0.5K0.5)NbO3solid solution ceramics are promising lead-free ceramics for high-frequency electromechanical transducer applications.
Pinning Effects on the Dielectric and Ferroelectric Properties of Mn-Doped Ba(Zr0.06Ti0.94)O3 Ceramics
Authors: Kuang Shu Juan , Tang Xin Gui , Wu Jun Bo , Jiang Yan Ping , Liu Qiu Xiang
Published: June 2011

Lead-free ceramics with the composition of Mn-doped Ba(Zr0.06Ti0.94)O3–xmol%MnO2(BZT6-xMn,x=0, 1 and 2) have been synthesized by a mixed oxide process. Structure and micrograph characterization were examined using X-ray diffraction (XRD) and scanning electron microscopy (SEM), which revealed that all samples have the orthorhombic phase with dense and the uniform microstructure. The grain size of Mn-doped BZT6 ceramics decreased with increasing MnO2doping. The effect of MnO2doping on the dielectric and ferroelectric properties was also investigated. The maximum dielectric permittivity decreased dramatically with increasing MnO2doping in the BZT6 ceramics. A peculiar double-hysteresis-like loop was observed. Mn ions as acceptor doping occupy the B site of ABO3in the form of Mn2+and Mn3+, which brought an increase in the oxygen vacancies concentration. The defect dipole model was explained the pinning mechanism.
Polarization and Properties of Laminated Fluoropolymer Films
Authors: Cao G. , Zhang Xiao Qing , Sun Z. , Lou Ke Xing , Xia Z.
Published: June 2011

Laminated fluoropolymer films with regular void structure, fabricated by using a process consisting of the patterning and fusion bonding steps, are polarized to be piezoelectric. The influence of the applied voltage on the piezoelectric d33 coefficient is investigated. The measurements of ferroelectric-like polarization-voltage hysteresis loops are taken to further understand the capability of polarization in the laminated films. The compressive Young’s moduli of the films are determined from the dielectric resonance spectra. The results show that the laminated fluoropolymer films are piezoelectric after proper charging. The maximum d33 coefficients of the five-layer laminated piezoelectrets are achieved at the applied voltage of 5 kV. The remnant charge density of 0.3 mC/m2 is obtained from the polarization-voltage hysteresis loop at a bias voltage of 4 kV. The measured anti-resonance frequency and calculated compressive Young’s modulus for the five-layer laminated films are 112 kHz and 0.48 MPa, respectively.
The Microstructure and Dielectric Properties of SrTiO3 Modified 0.9Pb(Mg1/3Nb2/3)O3-0.1PbTiO3 Ceramics
Authors: Liu Jing Song , Li Tao , Li Hui Qin , Xu You Chao , Yu Ji Qiang
Published: June 2011

The microstructure and dielectric properties of ferroelectric solutions which is formulated with (1-x)[0.9Pb(Mg1/3Nb2/3)O3-0.1PbTiO3]-x mol% SrTiO3(x=0, 1, 3 and 5) have been investigated. The ceramics was fabricated by a modified columbite route sintered at 1200 °C. The effects of dopants on microstructure, maximum dielectric constant (εm) and diffuseness of the phase transition, etc. have been studied. It is found that the maximum permittivity (εm) increases to 24968 for the ST-doped (1 mol %) sample, subsequently decreases with ST addition and its corresponding phase-transition-temperature (Tm) shifts to the lower temperature. The variation of εmis caused by the decrease of polar nano-region size, increase of the fluctuation of the component and the increase of the effective spontaneous polarization. The enhancement of relaxor behavior in the PMN-PT sample is explained by the decrease of FE/AFE coupling.