检索结果-南通市图书馆

The influence of spark plasma sintering temperatures on the microstructure,hardness,and elastic modulus of the nanocrystalline Al-xV alloys produced by high-energy ball milling

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2022年第27期122卷 68-76页

作者： J.Christudasjustus C.S.Witharamage Ganesh Walunj T.Borkar R.K.Gupta Department of Materials Science and Engineering North Carolina State UniversityRaleighNC 27606United States Department of Mechanical Engineering Cleveland State UniversityClevelandOH 44115United States

Al-xV alloys(x=2 at.%,5 at.%,10 at.%)with nanocrystalline structure and high solid solubility of V were produced in powder form by high-energy ball milling(HEBM).The alloy powders were consolidated by spark plasma sintering(SPS)employing a wide range of temperatures ranging from 200 to 400°*** microstructure and solid solubility of V in Al were investigated using X-ray diffraction analysis,scanning electron microscope and transmission electron *** microstructure was influenced by the SPS temperature and V content of the *** alloys exhibited high solid solubility of V–six orders of magnitude higher than that in equilibrium state and grain sizehigher than commercial *** example,Al-V alloy produced by SPS at 200℃ exhibited a hardness of 5.21 GPa along with elastic modulus of 96.21 *** evolution of the microstructure and hardness with SPS temperatures has been discussed.

关键词： Spark plasma sintering Aluminum alloys Nanocrystalline alloys high-energy ball milling Nanoindentation Hardness Elastic modulus

Microstructure and electrical properties of Y_2O_3-doped ZnO-based varistor ceramics prepared by high-energy ball milling

在线全文

学校读者我要写书评

暂无评论

Journal of University of Science and Technology Beijing 2007年第3期14卷 266-270页

作者： Hongyu Liu Xueming Ma Dongmei Jiang Wangzhou Shi College of Science Wuhan University of Science and Technology Wuhan 430081 China Department of Physics East China Normal University Shanghai 200062 China

Y2O3-doped ZnO-based varistor ceramics were prepared using high-energy ball milling （HEBM） and low-temperature sin- tering technique, with voltage-gradient of 1934-2197 V/mm, non-linear coefficients of 20.8-21.8, leakage currents of 0.59-1.04 μA, and densities of 5.46-5.57 g/cm3. With increasing Y2O3 content, the voltage-gradient increases because of the decrease of ZnO grain size; the non-linear coefficient and the leakage current improve but the density decreases because of more porosity; the donor con- centration and density of interface states decrease, whereas the barrier height and width increase because of the acceptor effect of Y2O3 in varistor ceramics.

关键词： inorganic materials electrical properties high-energy ball milling varistor microstructure low-temperature sintering zinc oxide yttrium oxide

Frequency and temperature dependent electrical characteristics of CaTiO_(3) nano-ceramic prepared by high-energy ball milling

在线全文

学校读者我要写书评

暂无评论

Journal of Advanced Ceramics 2013年第3期2卷 291-300页

作者： Subhanarayan SAHOO Umasankar DASH S.K.S.PARASHAR S.M.ALI School of Electrical Engineering KIIT UniversityBhubaneswar 751024India Center for Nanotechnology KIIT UniversityBhubaneswar 751024India School of Applied Sciences KIIT UniversityBhubaneswar 751024India

Nanocrystalline calcium titanate(CT)ceramic has been synthesized by a combination of solid-state reaction and high-energy ball *** nano-ceramic is characterized by X-ray diffraction(XRD),dielectric study and impedance *** XRD pattern shows single phase ceramic of orthorhombic *** frequency-dependent dielectric study shows that the dielectric constant is maximized at low frequencies and decreases with an increase in *** spectroscopy analyses reveal a non-Debye type relaxation phenomenon.A significant shift in impedance loss peaks toward the higher-frequency side indicates conduction in the material favoring the long-range motion of mobile charge *** grain conduction effect is observed from the complex impedance spectrum by the appearance of one semicircular arc in Nyquist *** is also observed that the resistance decreases with an increase in temperature showing a negative temperature coefficient of resistance(NTCR).Various thermistor parameters have been calculated by fitting with Steinhart-Hart *** modulus plots represent the presence of temperature-dependent electrical relaxation phenomenon with the *** frequency-dependent AC conductivity at different temperatures indicates that the conduction process is thermally *** activation energy has been calculated from an Arrhenius plot of DC conductivity and relaxation frequency.

关键词： high-energy ball milling dielectric study impedance spectroscopy thermistor conductivity

Behavior of Fe Powder During high-energy ball milling Cooperated with Dielectric Barrier Discharge Plasma

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2013年第1期26卷 63-68页

作者： Leyang DAI Marine Engineering Institute Jimei University

In this study, nanostructured Fe powders were synthesized following 10 hours of high-energy ball milling with a superimposed dielectric barrier discharge plasma （DBDP）. The mean size of the milled powder was approximately 100 nm with an average grain size of 16.2 nm. The influence of DBDP on the underlying grain refinement mechanisms during ball milling was investigated by scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, X-ray diffraction （XRD） and BET methods. Our results show that the Fe particles displayed an extraordinary plasticity during the early milling stages under the action of DBDP, and that the plastic deformation experienced by the Fe particles during this stage was more severe than that present in normal milling. A high concentration of spherical Fe particles, approximately 50-100 nm in diameter, was documented via TEM. We propose that these spherical particles were generated via high temperature disintegration as a result of DBDP electron bombardment during ball milling. Our results suggest that it may be possible to significantly refine metallic powders during milling via the superimposition of DBDP.

关键词： Dielectric barrier discharge plasma (DBDP) high-energy ball milling Nano-Fepowder Plastic deformation Elevated temperature disintegration

Microstructure and Electrical Properties of Er_2O_3-Doped ZnO-Based Varistor Ceramics Prepared by high-energy ball milling

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2007年第1期25卷 120-123页

作者：刘宏玉孔慧蒋冬梅石旺舟马学鸣 College of Science Wuhan University of Science and TechnologyWuhan 430081 China Shanghai AJ Nano-Science Development Co. Ltd.Shanghai 200237 China Department of Physics East China Normal UniversityShanghai 200062 China

The microstructure, electrical properties and density of ZnO-based varistor ceramics with different Er2O3 content prepared by high-energy ball milling （HEBM） and sintered at 800℃ were investigated. With increasing Er2O3 content, the ZnO grain size decreases due to the Er-rich phases inhibiting grain growth ; and nonlinear coefficient （ α ） decreases because of the decrease of barrier height （φB） The breakdown voltage （Eb） and density increase, whereas leakage current （IL） decreases with increasing Er2O3 content. The barrier height （φB）, donor concentration （Nd）, density of interface states （Ns） decrease and barrier width （ω） increases with increasing Er2O3 content due to acceptor effect of Er2O3 in varistor ceramics.

关键词： varistor Er2O3 microstructure electrical property high-energy ball milling low-temperature sintering rare earths

Synthesis of cathode material LiMn_(2)O_(4)for lithium-ion batteries by high-energy ball milling

在线全文

学校读者我要写书评

暂无评论

中国有色金属学会会刊：英文版 2000年第6期10卷 817-819页

作者：胡国荣彭忠东杨建红周贵海刘业翔 Department of Metallurgy Science and Engineering Central South UniversityChangsha 410083P.R.China

Using electrolytic manganese dioxide and Li 2CO 3 as starting materials, the precursor of LiMn 2O 4 as cathode materials for lithium ion batteries was obtained by high energy ball milling. The LiMn 2O 4 powder was synthesized by calcinating the as milling powder at 750 ℃ for 24 h. X ray diffraction, SEM, cyclic voltammograms and charge discharge were carried out to investigate the property of LiMn 2O 4 cathode materials. Results show that the synthesized material, which is of standard spinel structure, possesses high reversibility of electrochemistry. The capacity in EC DMC(1∶1)+1 mol/L LiPF 6 electrolyte during first discharge is determined to be 125 mA·h/g.[

关键词： lithium-ion batteries cathode materials high-energy ball milling

Optimization of Process Parameters for in high-energy ball milling of CNTs/Al2024 Composites Through Response Surface Methodology

在线全文

学校读者我要写书评

暂无评论

Journal of Harbin Institute of Technology(New Series) 2016年第1期23卷 53-59页

作者： Li Guo Xiaolan Cai Lei Zhou Cui Hu Changjiang Yang Ziyang Wang Wenzhong Zhang Gang Peng Faculty of Metallurgical and energy Engineering Kunming University of Science and Technology

The mathematical models are developed to evaluate the ultimate tensile strength( UTS) and hardness of CNTs / Al2024 composites fabricated by high-energy ball milling. The effects of the preparation variables which are milling time,rotational speed,mass fraction of CNTs and ball to powder ratio on UST and hardness of CNTs / Al2024 composites are investigated. Based on the central composite design( CCD),a quadratic model is developed to correlate the fabrication variables to the UST and hardness. From the analysis of variance( ANOVA),the most influential factor on each experimental design response is identified. The optimum conditions for preparing CNTs / Al2024 composites are found as follows: 1. 53 h milling time,900 r / min rotational speed,mass fraction of CNTs 2. 87% and ball to powder ratio 25 ∶ 1. The predicted maximum UST and hardness are 273.30 MPa and 261.36 HV,respectively. And the experimental values are 283.25 MPa and256.8 HV,respectively. It is indicated that the predicted UST and hardness after process optimization are found to agree satisfactory with the experimental values.

关键词： high-energy ball milling CNTs/Al2024 Central composite design Optimization

Bimodal-grained Ti fabricated by high-energy ball milling and spark plasma sintering

在线全文

学校读者我要写书评

暂无评论

Transactions of Nonferrous Metals Society of China 2016年第4期26卷 1170-1175页

作者：龙雁郭文晶李颖华南理工大学机械与汽车工程学院广东省金属新材料制备与成形重点实验室广州510640

Bimodal-grained Ti containing coarse and fine grains was fabricated by high-energy ball milling and spark plasma sintering (SPS). The microstructure and mechanical properties of the compacts sintered by Ti powders ball-milled for different time were studied. Experimental results indicated that when the ball-milling time increased, the microstructure of sintered Ti was firstly changed from coarse-grained to bimodal-grained structure, subsequently transformed to a homogeneous fine-grained structure. Compared with coarse-grained Ti and fine-grained Ti, bimodal-grained Ti exhibited balanced strength and ductility. The sample sintered from Ti powders ball-milled for 10 h consisting of 65.3% (volume fraction) fine-grained region (average grain size 1 μm) and 34.7% coarse-grained region (grain size > 5 μm) exhibited a compress strength of 1028 MPa as well as a plastic strain to failure of 22%.

关键词： titanium alloy high-energy ball milling spark plasma sintering bimodal-grained structure

Effects of high-energy ball milling oxide-doped and varistor ceramic powder on ZnO varistor

在线全文

学校读者我要写书评

暂无评论

Transactions of Nonferrous Metals Society of China 2012年第6期22卷 1423-1431页

作者：徐东唐冬梅焦雷袁宏明赵国平程晓农江苏大学材料科学与工程学院镇江212013 中国科学院半导体研究所半导体材料科学重点实验室北京100083 西安交通大学电力设备与电气绝缘国家重点实验室西安710049 常州江苏大学工程技术研究院常州213000 吉林大学化学学院无机合成与制备化学国家重点实验室长春130012

ZnO varistor ceramics doped with Bi2O3, Sb2O3, CO2O3, Cr2O3, and MnO2 were prepared separately by two high-energy ball milling processes： oxide-doped and varistor ceramic powder. A comparison in the electrical and microstructural properties of the samples obtained by both methods was made. The best results on these characteristics were achieved through the high-energy ball milling varistor ceramic powder route, obtaining a nonlinear coefficient of 57 and a breakdown field of 617 V/mm at a sintering temperature of 1000 ℃ for 3 h. The samples synthesized by this technique show not only high density value, 95% of the theoretical density, but also a homogeneous microstructure, which compete with those obtained by the high-energy ball milling oxide-doped powder route. With the advantage that the high-energy ball milling varistor ceramic powder route can refine grain, increase the driving force of sintering, accelerate the sintering process, and reduce the sintering temperature.

关键词： varistor ZnO high-energy ball milling electrical characteristic microstructure