检索结果-南通市图书馆

Hot Deformation Behavior of Aluminum Alloy 5083 for Automotive and Aviation Applications

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) 2013年第5期20卷 87-95页

作者： Rehan Qayyume Sha-Sha Zhao Hao-Yan Diao Chao-Li Ma Xiao-Wei Wu Yong Wang key laboratory of Aerospace Advanced materials and performance Ministry of EducationSchool of Material Science and Engineering Beihang University Beijing Research Institute of Mechanical & Electrical technology

This article concentrates on the investigation of hot deformation behavior of conventionally rolled commercial grade AA5083 alloy （A1-4. 5Mg）, for automotive and aviation applications. The superplastic response of the alloy was investigated at high strain rates （ 1〉10-3 s-I） , and a temperature range of 400℃to 550 ℃. An elongation to failure of 201% was achieved at low temperature （425 ℃ ） and high strain rate （ 10-2s-1 ）, which indicates sufficient ductility under hot deformation for manufacturing of extremely complex shapes using superplastic forming technology. Furthermore, the alloy exhibited a maximum elongation of about 470% at strain rate of 10-3s-1 and a temperature of 525℃. The deformation and failure mechanisms at both the critical conditions were studied as a function of strain rate and temperature. The contributions of strain-rate sensitivity and strain hardening were analyzed in relation to the observed tensile ductilities. Deformation mechanism of the alloy was also investigated with reference to Strain rate sensitivity index （m） and Activation energy （Q） for the given test condition. Empirical calculations reveal that dominant deformation mechanism responsible for hot deformation of the alloy is grain boundary sliding （ GBS）, which is further supported by deformed surface examination using scanning electron microscopy （SEM）. Fracture surfaces of the samples deformed to failure, at relatively higher and lower strain rates, was examined to investigate the micro- mechanisms governing failure. Phenomenon of cavity nucleation, growth and coalescence was observed to be the failure mechanism in the investigated alloy.

关键词： Al- Mg alloys superplasticiiy hot deformation microstructure evolution cavitation

The Influence of Annealing Temperature on the Structure and Properties of TiO_2 Films Prepared by Sputtering

在线全文

学校读者我要写书评

暂无评论

Journal of Wuhan University of technology(materials Science) 2006年第2期21卷 72-75页

作者：刘保顺 key laboratory for Silicate material Science and Engineering of ministry of education Wuhan University of Technology Wuhan 430070 China

The TiO2 fihus were prepared on slides by dc reactive magnetron spattering, then the samples were annealed at 300 ℃ ,350 ℃ ,400 ℃ ,450 ℃ ,500 ℃ and 550 ℃ , respectively. X-ray diffraction （XRD） was used to obtain the TiO2 film crystalline structure; X-ray photoelectron spectroscopy （ XPS ） was used to study the film surface stoichiometries ; surface morphologies were studied by scanning electron microscopy （SEM） ; the coatact angle was tested to indicate the TiO2 film wettability ; and the photocatalytic activity testing was couducted to evaluate the photocatalysis properties. The photocatalytic activity and contact angle testing results were correlated with the crystallinity , surface morphologies aud surface · OH concentration of TiO2 films. The samples with a higher polycrystalline anatase structure, rough surface and high · OH concentration displayed a better photoinduced hydrophilicity aud a stronger photocatalysis.

关键词： magnetron spattering photocatalysis activity heat treatment

Preparation and Magnetism of Gd_2O_3/X-NBR Composites

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2006年第Z2期24卷 335-339页

作者：曹建莉刘力吴小飞温世鹏金日光张立群 key laboratory of Beijing City on Preparation and Processing of Novel polymer materials Beijing University of Chemical Technology key laboratory for Nanomaterials Ministry of EducationBeijing University of Chemical TechnologyBeijing 100029China key laboratory of Science and technology of Controllable Chemical Reactions Ministry of EducationBeijing University of Chemical Technology

Series of Gd2O3/X-NBR composites were prepared by in-situ reaction at different temperatures (100 and 160℃) and different processing time. The influence of processing time and processing temperature on dispersion of Gd2O3 was investigated, and the relationship between magnetic property and temperature was also discussed. The results show that, the mass magnetizability (xg) descends as temperature rising. Processing temperature and time do not exhibit evidenced effects on the mass magnetizability (xg). All the composites show to be antiferromagnetic.

关键词： Gd2O3 X-NBR magnetism composite rare earths

Improvement in the performance of the Polylactic Acid Composites by Using Deep Eutectic Solvent Treated Pulp Fiber

在线全文

学校读者我要写书评

暂无评论

Journal of Renewable materials 2021年第11期9卷 1897-1911页

作者： Lei Tan Liangxian Liu Chaodong Liu Weihong Wang key laboratory of Bio-Based material Science and technology(ministry of education) Material Science and Engineering CollegeNortheast Forestry UniversityHarbin150040China

As the most favorable alternative to petroleum-based polymers,polylactic acid(PLA)which is the most promising degradable polymer has attracted increasing ***,the addition of cellulose to improve its strength often results in a reduction in its *** this work,microscale cellulose is first prepared from pulp fibers by using a deep eutectic solvent,and then is used as the reinforcement of PLA.A microcrystalline cellulose(MCC)/PLA sheet with uniform texture is obtained by the solution mixing,melt blending,hot-pressing and cold-pressing *** effects of MCC on the crystallization,thermal stability and mechanical properties of the PLA matrix were *** the addition of 1%cellulose fiber,the tensile strength of MCC/PLA composite sheet increased by 27%,and the elongation at break did not shown an evident *** strength enhancement mechanism was elucidated using scanning electron microscopy,differential scanning calorimetry,and dynamic thermomechanical *** energy dissipation during the deformation process and the compatibility of AMCC and rougher surface of MCC play important role in the strength ***,UV spectroscopy showed that the composite material absorbed some ultraviolet *** results show that the combined use of a deep eutectic solvent and solution mixing is an effective approach for improving the strength of PLA while maintaining its toughness.

关键词： Polylactic acid microcrystalline cellulose deep eutectic solvent mechanical properties

high-Pressure Preparation of high-Density Cu_2ZnSnS_4 materials

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

Chinese Physics Letters 2016年第7期33卷 113-116页

作者：李一鸣邱利霞丁战辉李永峰姚斌肖振宇朱品文 State key laboratory of Superhard material and College of Physics Jilin University key laboratory of Physics and technology for Advanced Batteries(ministry of education) College of PhysicsJilin University

high-density Cu2ZnSnS4 （CZTS） materials are prepared via the mechanical alloying and high pressure sintering method using Cu2S, ZnS and SnS2 as the raw materials. The morphological, structural, compositional and electrical properties of the materials are investigated by using x-ray diffraction, scanning electron microscopy, and energy dispersive x-ray spectroscopy, as well as by the Raman scattering and the Hall EFfect measurements. The CZTS synthesized under 5 GPa and 800℃ shows a p-type conductivity, with a resistivity of 9.69 × 10^-2 Ω.cm and a carrier concentration of 1.45 × 10^20 cm-3. It is contributed to by the large grains in the materials reducing the grain boundaries, thus effectively reducing the recombination of the charge carriers.

关键词： of in ZnS it CZTS high-Pressure Preparation of high-Density Cu2ZnSnS4 materials Cu

high-density and narrow size-distribution InAs quantum dots formed by a modified two-step growth

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2008年第1期17卷 323-327页

作者：黄社松牛智川詹锋倪海桥赵欢吴东海孙征 State key laboratory for Superlattices and Microstructures Institute of SemiconductorsChinese Academy of Sciences The key laboratory of Beam technology and material Modification of ministry of education Beijing Normal University

We develop a modified two-step method of growing high-density and narrow size-distribution InAs/GaAs quantum dots （QDs） by molecular beam epitaxy. In the first step, high-density small InAs QDs are formed by optimizing the continuous deposition amount. In the second step, deposition is carried out with a long growth interruption for every 0.1 InAs monolayer. Atomic force microscope images show that the high-density （～5.9 × 10^11 cm^-2） good size-uniformity InAs QDs are achieved. The strong intensity and narrow linewidth （27.7 meV） of the photoluminescence spectrum show that the QDs grown in this two-step method have a good optical quality.

关键词： molecular beam epitaxy quantum dots a modified two-step growth

Environmental load of solid wood floor production from larch grown at different planting densities based on a life cycle assessment

在线全文

学校读者我要写书评

暂无评论

Journal of Forestry Research 2018年第5期29卷 1443-1448页

作者： Siying Hu Xin Guan Minghui Guo Jinman Wang key laboratory of Bio-Based material Science and technology of the ministry of education Northeast Forestry University College of material Engineering Fujian Agriculture and Forestry University

As one of the main structural units in a building,a solid wood floor has significant strategic research value for low-carbon energy *** the production line of a solid larch wood floor as a case study,we assessed the environmental load during production based upon a life cycle *** GaBi 6.0 software,we analyzed the associated carbon sequestration during floor production,with the initial planting density serving as the disturbance factor in a modular *** results indicated that the cutting and finishing steps have relatively intense,negative influences on the environment,whereas transportation,ripping,and trimming do ***,recycling biomass waste has the potential to reduce greenhouse gas *** the initial planting density was 3.0×3.0 m,carbon sequestration was relatively *** the emissions of freshwater pollutants,volatile organic compounds,and fine particulate matter（matter with a 2.5-μm diameter） were comparatively high,the reduction of greenhouse gas emissions was still excellent at this planting density.

关键词： Environmental effect Larch Life cycle assessment Planting density Solid wood floor

Influence of Zn ion implantation on structures and field emission properties of multi-walled carbon nanotube arrays

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2010年第3期53卷 776-781页

作者： CHEN KeFan,DENG JianHua,ZHAO Fei,CHENG GuoAn &ZHENG RuiTing key laboratory of Beam technology and material Modification of ministry of education,College of Nuclear Science and technology,Beijing Normal University,Beijing100875,China key laboratory of Beam technology and material Modification of ministry of education College of Nuclear Science and Technology Beijing Normal University Beijing China

The structures and field emission properties of multi-walled carbon nanotube arrays implanted with Zn+ by MEVVA ion implanter have been *** results revealed that Zn+implantation induced structural damage and that the top of carbon nanotubes with multi-layered graphite structure were transformed into carbon nanowires with amorphous ***,C:Zn solid solution was synthesized after Zn+ *** turn-on field and threshold field were 0.80 and 1.31 V/μm,respectively for original multi-walled carbon nanotube arrays and were reduced to 0.66 and 1.04 V/μm due to the synthesis of C and Zn composite,in which the work function was reduced after low doses of Zn+*** is indicated that low doses of Zn+implantation can improve field emission performance of multi-walled carbon nanotube ***,high doses of Zn+implantation can reduce field emission properties of multi-walled carbon nanotube arrays,because radiation damage reduces the electric field enhancement factor.

关键词： multi-walled carbon nanotubes ion implantation field electron emission

Effects of Crystallization Temperature and Blend Ratio on the Crystal Structure of Poly(butylene adipate) in the Poly(butylene adipate)/Poly(butylene succinate) Blends

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of polymer Science 2014年第4期32卷 488-496页

作者： Hai-jun Wang Hui-ping Feng 王学川 Pei-ying Guo Ting-shan Zhao Long-fang Ren Xi-huai Qiang Yu-hao Xiang 晏超 key laboratory of Chemistry and technology for Light Chemical Industry Ministry of EducationShaanxi University of Science and Technology School of material Science & Engineering Jiangsu University of Science and Technology

The effects of crystallization temperature and blend ratio on the polymorphic crystal structures of poly（butylene adipate）（PBA） in poly（butylene succinate）（PBS）/poly（butylene adipate）（PBS/PBA） blends were studied by means of differential scanning calorimetry （DSC）, wide-angle X-ray diffraction （XRD） and atomic force microscopy （AFM）. It was revealed that the polymorphism of PBA can be regulated by the blend ratio even in a non-isothermal crystallization process. The results demonstrate that high temperature favors fiat-on α crystals, while low temperature contributes to edge-on β crystals. It was also found that the effect of blend ratio on the crystallization mechanism of PBA is well coincident with that of the crystallization temperature. The increment of PBS content in the PBS/PBA blend gives rise to more β-form crystals of PBA. For those PBS/PBA blends with low PBA content, the interlamellar phase segregation of PBA makes its molecular chains so difficult to diffuse from one isolated microdomain to another that high crystallization temperature and sufficiently long crystallization time will be required if the PBA α-type crystals are targeted.

关键词： Blends Crystallization Poly(butylene adipate) Poly(butylene succinate).