检索结果-南通市图书馆

Rare Metals 2020年第10期39卷 1222-1228页

作者： Cheng Chen Xiao-mei Feng yi-fu shen School of Mechanical and Power Engineering Nanjing Tech UniversityNanjing 211800China College of Materials Science and Technology Nanjing University of Aeronautics and AstronauticsNanjing 210016China

Mechanical alloying method was applied to fabricate coating with amorphous structure on pure Cu *** microstructure,the phase composition and the mechanical properties including microhardness and wear resistance of the coating were,respectively,characterized and *** results show that the coating is rough but *** has favorable adhesion to the *** coating is made up of an inner composite layer and an outer amorphous *** microhardness and the wear resistance of the pure Cu substrate are improved because of the bilayer *** formation mechanism of the coating was *** as-synthesized coating is considered to be effective to strengthen the surface of pure Cu substrate.

关键词： Coating Amorphous Mechanical alloying Surface reinforcement

Formation mechanism and mechanical properties of surface nanocrystallized Ti-6Al-4V alloy processed by surface mechanical attrition treatment

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2023年第4期42卷 1343-1352页

作者： yi-Feng Li Cheng Chen J.Ranabhat yi-fu shen College of Materials Science and Technology Nanjing University of Aeronautics and AstronauticsNanjing210016China

In the present work,surface mechanical attrition treatment(SMAT)was proposed to achieve surface nanocrystallization on Ti-6Al-4V surface via high-energy planetary ball milling method using a planetary ball *** characteristics of microstructure were studied using different *** nanocrystallization is achieved on Ti-6Al-4V *** process of refinement could be summarized into four *** the refinement process,the reticular continuous beta phase performs a significant role,it cracked,broke up and moved to each side along the grain *** movement of beta grains has the capabilities of effectively optimizing the grain orientation and accelerating the further refinement of alpha *** also plays an important role during the *** grain orientation between different types of grains seems to be larger than that of same type *** interface will be divided into smaller nanocrystalline grains once the dislocation density breaks the ***,the balance will be achieved again and owns a higher critical value which cannot be broken,then a stable grain size can be achieved *** results of microhardness,friction coefficient and wear mass loss tests of SMAT samples indicate that the mechanical behaviors of substrate are greatly enhanced after this novel SMAT treatment.

关键词： Surface nanocrystallization Dual-phase titanium alloy SMAT Mechanical properties

Effect of process parameters on the microstructure and properties of laser-clad FeNiCoCrTi0.5 high-entropy alloy coating

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2020年第5期27卷 630-639页

作者： ying Zhang Teng-fei Han Meng Xiao yi-fu shen College of Materials Science and Technology Nanjing University of Aeronautics and Astronautics(NUAA)Nanjing 210016China Nanjing Institute of Advanced Laser Technology Nanjing 210038China

FeNiCoCrTi0.5 coatings with different process parameters were fabricated by laser cladding. The macro-morphology, phase, microstructure, hardness, and wear resistance of each coating were studied. The smoothness and dilution rate of the FeNiCoCrTi0.5 coating generally increased with the increase of specific energy(Es), which is the laser irradiation energy received by a unit area. FeNiCoCrTi0.5 coatings at different parameters had bcc, fcc, and Ti-rich phases as well as equiaxed, dendritic, and columnar structures. When Es increased, the size of each structure increased and the distribution area of the columnar and dendritic structures changed. The prepared FeNiCoCrTi0.5 coating with the Es of 72.22 J·mm-2 had the highest hardness and the best wear resistance, the highest hardness of the coating reached HV 498.37, which is twice the substrate hardness. The average hardness of the FeNiCoCrTi0.5 coating with the Es of 72.22 J·mm-2 was 15.8% higher than the lowest average hardness of the coating with the Es of 108.33 J·mm-2. The worn surface morphologies indicate that the FeNiCoCrTi0.5 coatings exhibited abrasive wear.

关键词： high-entropy alloy coating 45 steel laser cladding microstructure wear resistance

The role of high-energy computed radiography(CR)in radiotherapy

在线全文

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2009年第1期20卷 31-36页

作者： LI Zhaobin SUN yi LU Yaohong fu shen Department of Radiation Oncology the No.6 Hospital of Shanghai JiaoTong University Shanghai 200233 China

Computed radiography(CR)imaging has high irradiation tolerance and it is easy to archive CR images along with other image information by Digital Imaging and Communications in Medicine(DICOM)format,and to process *** can be used in radiation Quality Control(QC)task and verification of treatment *** this paper,the role of high-energy CR in radiation oncology is *** patients were imaged by CR system and EPID before *** verification images were acquired with 1–2 MU(Monitor Unit)using 6 MV *** for a linac was done with film and high-energy CR to collect the data on daily,weekly and monthly *** QC included Multileaf Collimators(MLC)calibration and mechanical iso-centre *** was also adapted to verify patient position,the film was used to compare with digitally reconstructed radiographs(DRR)and portal image from EPID. Treatment setting-up was verified based on the result of *** quality verification images could be acquired by the CR *** to EPID,the results showed that the system was suitable for practical use to acquire daily verification images,and it was useful to fulfill part of quality assurance(QA)in radiation *** quality of image acquired by the high-energy CR system is comparable or even better than DRRs and portal images. The final treatment set-up for the patients could be verified more accurately with the CR system.

关键词：计算机X摄影方法影像效果图像融合医学应用

Effect of rare earth content on microstructure and corrosion resistance of hot-dip Zn-5Al alloy coated steel wire for bridge cables

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2023年第10期30卷 2101-2110页

作者： Xiao-xiong Zhu yi-fu shen Cheng-tao Li Xiang Dai Guo-hao Xiao College of Materials Science and Technology Nanjing University of Aeronautics and Astronautics(NUAA)Nanjing 211106JiangsuChina Jiangsu Tokyo Rope Co. Ltd.Jiangyin 214425JiangsuChina Nanjing Vocational University of Industry Technology Nanjing 210023JiangsuChina

The effects of the content of rare earth elements on the microstructure and properties of hot-dip Zn-5 Al alloy steel wire for bridge cables were *** microstructure of the hot-dip coating was analyzed using an optical microscope and a scanning electron microscope equipped with an energy-dispersive *** bonding force between the hot-dip coating and steel wire was determined by the winding *** corrosion resistance of the steel wire hot-dip coating was tested by the electrochemical *** hot-dip Zn-5A1 alloy coating has a corrosion-resistant structure composed of a zinc-rich phase and an aluminum-rich *** to the enhanced bonding force,the micro structure of the hot-dip coating of the Zn-5A1 alloy with rare earth elements is more compact and uniform than that without rare earth *** addition of rare earth elements improves the corrosion resistance of Zn-5A1 alloy coated steel *** to the rare earth segregation,which prevents the corrosion of the grain boundary and enhances the anti-intergranular corrosion performance,steel wire exhibits the optimum corrosion resistance when the content of rare earth elements is 0.08 wt.%.

关键词： Bridge cable steel wire Hot dipping Rare earth content Corrosion resistance Microstructure

Microstructures and properties of Cu-Cr-W composite coatings fabricated by surface mechanical alloying technique

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

Rare Metals 2022年第12期41卷 4248-4256页

作者： Jia-Ping Zhang Xiao-Mei Feng yi-fu shen Cheng Chen Cui-Yuan Duan College of Materials Science and Technology Nanjing University of Aeronautics and AstronauticsNanjing 210016China

Cu-Cr-W composite coatings were prepared by mechanical alloying(MA)method using different powder ratios,rotational speeds and milling *** micro structures and chemical compositions of as-synthesized coatings were analyzed by scanning electron microscopy(SEM)and energy-dispersive spectroscopy(EDS).Phases of ball-milled powders were identified by X-ray diffraction(XRD).The results indicate that the coating fabricated with powder ratio of 40 wt%Cu-Cr-W has better surface and cross-sectional microstructures and higher *** comparisons of cross-sectional micro structures of the coatings fabricated at different rotational speeds suggest that rotational speed of 300 r·min-1is the optimal for fabrication the coating,and the optimal milling time for the formation of coating is 7 *** results of microhardness test show that the hardness of the substrate is largely improved because of the as-fabricated *** results of the friction and wear tests indicate that the wear resistance of the copper substrate is improved after the deposition of Cu-Cr-W coating on *** coating fabricated for 7 h exhibits the lowest friction coefficient,indicating its favorable friction and wear *** formation mechanism of the coating was *** to the investigations in this work,the Cu-Cr-W coating fabricated by MA method is considered to be effective to reinforce the copper substrate.

关键词： Mechanical alloying Composite coating Powder ratio Processing parameter

Reaction mechanism between Al_(2)O_(3)–MgO refractory materials and rare earth high-carbon heavy rail steel

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2024年第5期31卷 1153-1163页

作者： yi Wang Guang-jie Song Ping shen Jian-zhong He Da-xian Zhang Jian-xun fu Center for Advanced Solidification Technology(CAST) School of Materials Science and EngineeringState Key Laboratory of Advanced Special SteelShanghai UniversityShanghai200444China State Key Laboratory of Baiyunebo Rare Earth Resources Research and Comprehensive Utilization Baotou014030Inner MongoliaChina Inner Mongolia Baotou Steel Union Co. Ltd.Baotou014030Inner MongoliaChina

Submerged entry nozzle(SEN)clogging is a major problem affecting the production quality of rare earth steel,and finding a suitable refractory outlet can significantly reduce production *** explore the relationship between refractory composition and interface interaction,unprotected coated Al_(2)O_(3)–MgO refractories and SiO2-coated Al_(2)O_(3)–MgO refractories were added to rare earth high-carbon heavy rail steel under laboratory conditions,and the Al_(2)O_(3)–MgO refractory was found to be more *** results show that,from the epoxy resin side to the refractory side,the contour of the refractory interface reaction layer can be divided into two main layers:an iron-rich reaction layer and an iron-poor reaction *** based on the spherical model suggest that the adhesion force is proportional to the size of the refractory particles and inclusions,and the same result applies to the surface *** the inclusions at a smaller size has a specific effect on alleviating the erosion of *** with the erosion mechanism of Al_(2)O_(3)–MgO refractories,the interface reaction mechanism between Al_(2)O_(3)–MgO refractories and molten steel was proposed,which provides ideas for solving SEN clogging.

关键词： Rare earth high-carbon heavy rail steel Al_(2)O_(3)-MgO refractory Adhesion Surface tension Interface interaction

Rapidly growing primordial black holes as seeds of the massive high-redshift JWST Galaxies

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

Science China(Physics,Mechanics & Astronomy) 2024年第10期67卷 139-146页

作者： Guan-Wen Yuan Lei Lei Yuan-Zhu Wang Bo Wang yi-ying Wang Chao Chen Zhao-Qiang shen yi-fu Cai yi-Zhong Fan Key Laboratory of Dark Matter and Space Astronomy Purple Mountain ObservatoryChinese Academy of SciencesNanjing 210023China School of Astronomy and Space Science University of Science and Technology of ChinaHefei 230026China Institute of High Energy Physics Chinese Academy of SciencesBeijing 100049China Deep Space Exploration Laboratory/Department of Astronomy School of Physical SciencesUniversity of Science and Technology of ChinaHefei 230026China Jockey Club Institute for Advanced Study The Hong Kong University of Science and TechnologyHong KongChina

A group of massive galaxies at redshifts of z■7 have been recently detected by the James Webb Space Telescope(JWST),which were unexpected to form at such an early time within the standard Big Bang *** this work,we propose that this puzzle can be explained by the presence of some primordial black holes(PBHs)with a mass of~1000M_(⊙).These PBHs act as seeds for early galaxy formation with masses of~10^(8)-10^(10)M_(⊙)at high redshift,hence accounting for the JWST *** use a hierarchical Bayesian inference framework to constrain the PBH mass distribution models,and find that the Lognormal model with the M_(c)~750M_(⊙)is preferred over other *** rapidly growing BHs are expected to have strong radiation and may appear as high-redshift compact objects,similar to those recently discovered by *** we focused on PBHs in this work,the bound on the initial mass of the seed black holes remains robust even if they were formed through astrophysical channels.

关键词： primordial black hole dark matter halo black hole accretion primordial galaxies

Analytical computation of magnetic field in coil-dominated superconducting quadrupole magnets based on racetrack coils

在线全文

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2024年第4期35卷 119-135页

作者： Chuang shen ying-Shun Zhu fu-San Chen China Spallation Neutron Source Institute of High Energy PhysicsChinese Academy of Sciences1 Zhongziyuan RoadDongguan 523000China Institute of High Energy Physics Chinese Academy of Sciences19B Yuquan RoadBeijing 100049China University of Chinese Academy of Sciences Beijing 100049China

Currently,three types of superconducting quadrupole magnets are used in particle accelerators:cos 2θ,CCT,and ***,all three coil configurations have complex spatial geometries,which make magnet manufacturing and strain-sensitive superconductor applications *** with the three existing quadrupole coils,the racetrack quadrupole coil has a simple shape and manufacturing process,but there have been few theoretical *** this paper,the two-dimensional and three-dimensional analytical expressions for the magnetic field in coil-dominated racetrack superconducting quadrupole magnets are *** analytical expressions of the field harmonics and gradient are fully resolved and depend only on the geometric parameters of the coil and current ***,a genetic algorithm is applied to obtain a solution for the coil geometry parameters with field harmonics on the order of 10^(-4).Finally,considering the practical engineering needs of the accelerator interaction region,electromagnetic design examples of racetrack quadrupole magnets with high gradients,large apertures,and small apertures are described,and the application prospects of racetrack quadrupole coils are analyzed.

关键词： Superconducting quadrupole magnet Racetrack coil Multipole field Genetic algorithm Magnetic design

Recent progress of cobalt-based electrocatalysts for water splitting: Electron modulation, surface reconstitution, and applications

在线全文

学校读者我要写书评

暂无评论

Nano Research 2024年第4期17卷 2234-2269页

作者： Zhijian Liang Di shen Lei Wang Honggang fu Key Laboratory of functional Inorganic Material Chemistry Ministry of Education of the People’s Republic of ChinaHeilongjiang UniversityHarbin 150080China

Electrocatalytic water splitting is an essential and effective means to produce green hydrogen energy structures,so it is necessary to develop non-precious metal catalysts to replace precious ***-based catalysts present effective alternatives due to the diverse valence states,adjustable electronic structures,and plentiful *** this review,the catalytic mechanisms of hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)for electrocatalytic water splitting are ***,the synthesis strategies of various cobalt-based catalysts are systematically summarized,followed by the relationships between the structure and performance ***,the effects of d-band center and spin regulation for cobalt-based catalysts are also ***,the dynamic electronic and structural devolution of cobalt-based catalysts are elucidated by combining a series of in-situ ***,we highlight the challenges and future developed directions of cobalt-based catalysts for electrocatalytic water splitting.

关键词： cobalt-based electrocatalysts water splitting electron modulation surface reconfiguration