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Synthesis and Characterizations of nanocrystalline WC-Co Composite Powders by a Unique Ball Milling Process

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Journal of materials Science & Technology 2004年第1期20卷 7-10页

作者： Jun SHEN, Jianfei SUN and Faming ZHANGSchool of materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China Sch. of Mat. Sci. and Eng. Harbin Inst. of Technol. Harbin 150001 China

In order to explore the high efficiency of fabricating nanocrystalline WC-Co composite powders, this paper presented a unique high energy ball milling process with variable rotation rate and repeatious circulation, by which nanocrystalline WC-10Co-0.8VC-0.2Cr3C2 (wt pct) composite powders with mean grain size of 25 nm were prepared in 32 min, and the quantity of the powders for a batch was as much as 800 grams. The as-prepared powders were analyzed and characterized by chemical analysis, X-ray diffraction (XRD), transmission electron microscopy (TEM) and differential thermal analysis (DTA). The results show that high energy ball milling with variable rotation rates and repeatious circulation could be used to produce nanocrystalline WC-Co powder composites with high efficiency. The compositions of the powders meet its specifications with low impurity content. The mean grain size decreases, lattice distortion and system energy increase with increasing the milling time. The morphology of nanocrystalline WC-Co particles displays dominantiy sphere shape and their particle sizes are all lower than 80 nm. The eutectic temperature of the nanocrystalline WC-10Co-0.8VC-0.2Cr3C2 composites is about 1280℃.

关键词： nanocrystalline material WC-Co composite High energy ball milling

Confinement-induced nanocrystal alignment of conjugated polymer by the soft-stamped nanoimprint lithography

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Chinese Physics B 2015年第10期24卷 274-280页

作者：李晓慧俞计成陆乃彦张卫东翁雨燕顾臻 Center for Soft Condensed Matter Physics and Interdisciplinary Research & College of Physics Optoelectronics and EnergySoochow University Joint Department of Biomedical Engineering University of North Carolina at Chapel Hill and North Carolina State University

Soft-stamped nanoimprint lithography（NIL） is considered as one of the most effective processes of nanoscale patterning because of its low cost and high throughput. In this work, this method is used to emboss the poly（9, 9-dioctylfluorene）film. By reducing the linewidth of the nanogratings on the stamp, the orientations of nanocrystals are confined along the grating vector in the nanoimprint process, where the confinement linewidth is comparable to the geometrical size of the nanocrystal. When the linewidth is about 400 nm, the poly（9, 9-dioctylfluorene）（PFO） nanocrystals could be orderly arranged in the nanogratings, so that both pattern transfer and well-aligned nanocrystal arrangement could be achieved in a single step by the soft-stamped NIL. The relevant mechanism of the nanocrystalline alignment in these nanogratings is fully discussed. The modulation of nanocrystal alignment is of benefit to the charge mobilities and other performances of PFO-based devices for the future applications.

关键词： conjugated polymer soft lithography nanocrystalline material x-ray technique

In-situ synchrotron high energy X-ray diffraction study of spontaneous reorientation of R phase upon cooling in nanocrystalline Ti_(50)Ni_(45.5)Fe_(4.5)alloy

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Rare Metals 2022年第6期41卷 1948-1954页

作者： Zhi-Yuan Ma Yu-Xuan Chen Yang Ren Kai-Yuan Yu Da-Qiang Jiang Yi-Nong Liu Li-Shan Cui Department of materials Science and Engineering China University of Petroleum(Beijing)Beijing 102249China Department of Physics City University of Hong KongHong Kong 999077China Centre for Neutron Scattering City University of Hong KongHong Kong 999077China Department of Mechanical Engineering The University of Western AustraliaPerthWA 6009Australia

This study investigated a peculiar phenomenon of self-reorientation of thermally formed R phase in nanocrystalline Ti_(50)Ni_(45.5)Fe_(4.5)by means of in-situ syn-chrotron high energy X-ray diffraction(HE-XRD).Two samples with different average grain sizes of 40 and 90 nm were investigated.R phase in the 40-nm grain size sample was found to self-reorient gradually upon cooling,whereas the same phenomenon did not occur in the 90-nm grain size *** self-reorientation process is attributed to the development and evolution of an internal stress anisotropy caused by the second order continuous lattice distortion of R phase upon further cooling in the small nanograined matrix,which lacks the self-accommodation mechanism for internal stress cancellation.

关键词： TiNiFe Martensitic transformation R phase reorientation Synchrotron diffraction nanocrystalline material

Desorption behaviour and microstructure change of nanostructured hydrided AZ31 Mg alloy powders

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Transactions of Nonferrous Metals Society of China 2010年第4期20卷 597-601页

作者：王珩胡连喜袁媛王尔德 School of materials Science and Engineering Harbin Institute of Technology

In order to optimize the dehydriding process for producing nanocrystalline Mg alloy powders by hydriding-dehydriding treatment,nano-structured as-hydrided Mg-3%Al-1%Zn(AZ31 Mg)(mass fraction)alloy powders were thermally dehydrided at various temperatures from 275 to 375℃.The kinetics of hydrogen desorption was examined by hydrogen discharge measurement during *** microstructure of the as-hydrided and the subsequently fully dehydrided alloy powders was investigated by X-ray diffraction analysis(XRD)and transmission electron microscopy(TEM),*** the desorption kinetics and the grain size of the alloy after complete dehydriding were found to be strongly dependent on the processing *** higher the temperature,the faster the desorption,and the more significant the grain *** the desorption temperature was raised from 300 to 375℃,the time to achieve complete dehydriding was shortened from 190 to 20 min,and the average grain size increased correspondingly from 20 to 58 nm.

关键词： Mg hydride dehydriding Mg alloy nanocrystalline material

Influence of heat treatment on nanocrystalline zirconia powder and plasma-sprayed thermal barrier coatings

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Transactions of Nonferrous Metals Society of China 2010年第12期20卷 2272-2280页

作者：蒋显亮刘纯波刘敏朱晖朝 School of materials Science and Engineering Central South University Guangzhou Research Institute of Non-ferrous Metals

Nanostructured zirconia top coat was deposited by air plasma spray and NiCoCrAlTaY bond coat was deposited on Ni substrate by low pressure plasma *** and conventional thermal barrier coatings were heat-treated at temperature varying from 1050 to 1 250oC for 2-20 *** results show that obvious grain growth was found in both nanostructured and conventional thermal barrier coatings(TBCs)after high temperature heat ***/tetragonal phases were transformed into cubic phase in the agglomerated nano-powder after *** cubic phase content increased with increasing calcination *** of the powder made the yttria distributed on the surface of the nanocrystalline particles dissolve in zirconia when grains *** from the phase constituent of the as-sprayed conventional TBC which consisted of diffusionlesstransformed tetragonal,the as-sprayed nanostructured TBC consisted of cubic phase.

关键词： nanocrystalline material zirconia thermal barrier coating heat treatment phase composition

Effect of Zn^(2+) Content on the Microstructure and Magnetic Properties of nanocrystalline Ni_(1-x)Zn_xFe_2O_4 Ferrite by a Spraying-coprecipitation Method

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Journal of Wuhan University of Technology(materials Science) 2010年第3期25卷 429-431页

作者：刘银 College of materials Science and Engineering Anhui University of Science and Technology

nanocrystalline Ni1-xZnxFe2O4 ferrites with 0≤x≤1 were successfully prepared by a spraying-coprecipitation *** microstructure was investigated by using XRD and *** properties were measured with vibrating sample magnetometer（VSM） at room *** results show that the grain size of nanocrystalline Ni1-xZnxFe2O4 ferrite calcined at 600 ℃ for 1.5 h is about 30 *** parameter and specific saturation magnetization Ms of nanocrystalline Ni1-xZnxFe2O4 ferrite increase with the Zn^2＋ ions content at room temperature,and maximum Ms is 66.8 A·m^2·kg^-1 as the Zn^2＋ ions content is around 0.5,and coercivity Hc of the nanocrystalline Ni1-xZnxFe2O4 ferrite decreases with Zn^2＋ ions content.

关键词： nanocrystalline material Ni-Zn ferrite spraying-coprecipitation method magnetic properties microstructure

Rational Fabrication of Size Tunable SnO2 Hollow Microspheres

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Chemical Research in Chinese Universities 2015年第5期31卷 719-723页

作者： HUANG Zhiqiang GUO Jia WANG Xiaoling GAO Haiyan YU Jianguo ZHAO Yongnan LI Guodong Institute of Nanostructured materials & Tianjin Key Laboratory of Fiber Modification and Functional Fiber School of Materials Science and Engineering Tianjin Polytechnic University Tianjin 300387 P. R. China Respiratory Department Jilin Province People's Hospital Changchun 130021 P. R. China State Key Laboratory of Inorganic Synthesis and Preparative Chemistry College of Chemistry Jilin University Changehun 130012 P. R. China

A designed solution route was developed to fabricate size tunable SnO2 hollow microspheres based on the sol-gel theory. The hydrolysis of SnSO4 released protons to form SnO2 particulates and induced the decrease of pH value. To minimize the high surface energy, the SnO2 particulates tended to assemble into large particles, the size of which was affected by the electrolyte concentration or pH value. Elevating SnSO4 content aroused the decrease of the pH value that directed to the shrinkage of the aggregated particle size of SnO2. Size tunable SnO2 hollow micro- spheres were then rationally fabricated under solvothermal conditions via Ostwald ripening by simply adjusting the SnSO4 concentration. The in situ pH decrease directed to the shrinkage of the particle size from 270 nm to 112 nm. The formation mechanism was confirmed and rationally elucidated by the time dependant morphology evolution. Charge-discharge tests revealed that the reduced particle size aroused an improved lithium ion battery performance.

关键词： Hollow microsphere Solvothermal synthesis nanocrystalline material Tin oxide

Solvothermal synthesis and characterization of nanocrystalline vanadium-chromium composite oxides and catalytic ammoxidation of 2,6-dichlorotoluene

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Chinese Journal of Catalysis 2018年第11期39卷 1814-1820页

作者： Yeying Huang Tingcheng Li Qingliang You Xiangqian You Qian Zhang Daohong Zhang Guangyong Xie Key Laboratory of Catalysis and materials Science of the State Ethnic Affairs Commission&Ministry of Education South‐Central University for NationalitiesWuhan 430074HubeiChina Key Laboratory of Optoelectronic Chemical materials and Devices Ministry of EducationSchool of Chemical and Environmental EngineeringJianghan UniversityWuhan 430056HubeiChina

Vanadium‐chromium oxides(VCrO)were usually prepared by high‐temperature solid‐state reactions;however,mixed phases were frequently produced and the morphology of the products was not well *** this work,we prepared amorphous VCrO precursors by using V2O5 and CrO3 and alcohols or mixtures of alcohol and water via solvothermal reaction at 180°*** precursors were then calcined under nitrogen at various *** products were characterized by powder X‐ray diffraction,transmission electron microscopy,and X‐ray photoelectron *** was revealed that pure‐phase nanocrystalline orthorhombic CrVO4 was obtained when methanol or methanol/water was used as the solvothermal medium and the precursor was calcined at 700°*** size of the CrVO4 crystals was around 500 nm when methanol was used,whereas it reduced significantly to less than 50 nm when a mixture of methanol and water was *** sizes could be effectively tuned from 10 to 50 nm by varying the methanol/water volume *** the best of our knowledge,this is the first report on the synthesis of pure‐phase CrVO4 *** nano‐CrVO4 showed almost the highest catalytic activity for the ammoxidation of 2,6‐dichlorotoluene to 2,6‐dichlorobenzonitrile among the reported bi‐component composite oxides,owing to its smaller particle size,larger specific surface area,and more exposed active centers.

关键词： CrVO4 nanocrystalline material Composite oxide Solvothermal synthesis Ammoxidation

Microstructure and magnetic characteristics of nanocrystalline Ni0.5Zn0.5 ferrite synthesized by a spraying-coprecipitation method

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Chinese Physics B 2007年第12期16卷 3837-3842页

作者：刘银丘泰 College of materials Science and Engineering Nanjing University of Technology Nanjing 210009 China Department of materials Science and Engineering Anhui University of Science and Technology Huainan 232001 China

nanocrystalline Ni0.5Zn0.5 ferrite with average grain sizes ranging from 10 to 100 nm is prepared by using a spraying-coprecipitation method. The results indicate that the nanocrystalline Ni0.5Zn0.5 ferrite is ferromagnetic without the superparamagnetic phenomenon observed at room temperature. Specific saturation magnetization of nanocrystalline ***.5 ferrite increases from 40.2 to 75.6 emu/g as grain size increases from 11 to 94nm. Coercivity of nanocrystalline Ni0.5Zn0.5 ferrite increases monotonically when d 〈 62 *** relationship between the coercivity and the mean grain size is well fitted into a relation Hc - d^3. A theoretically evaluated value of the critical grain size is 141nm larger than the experimental value 62nm for nanocrystalline Ni0.5Zn0.5 ferrite. The magnetic behaviour of nanocrystalline Ni0.5Zn0.5 ferrite may be explained by using the random anisotropy theory.

关键词： nanocrystalline material Ni0.5Zn0.5 ferrite spraying-coprecipitation method