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Spherical modification of tungsten powder by particle composite system

Rare Metals 2022年第6期41卷 1972-1976页

作者： Cong-Cong Wang Cheng-Chang Jia Peng Gao Guo-Sheng Gai Yu-Fen Yang School of Materials Science and Engineering University of Science and Technology BeijingBeijing 100083China Powder Technology R&D Group Department of Material Science and EngineeringTsinghua UniversityBeijing 100084China

Owing to contradiction between increasing demand of spherical tungsten powder and limitation of traditional manufacturing technology,a novel preparation method was developed to sphericize the polygonal tungsten powder by means of modification of particle composite *** powder particles were modified by par-ticle composite system,and detailed characterization by scanning electron microscopy(SEM)was *** size distribution and function mechanism were analyzed,and the internal relationship between average diameter and processing time was *** results show that the spherical tungsten powder with an average diameter of 6.41μm is obtained from polyhedral tungsten powder with an average diameter of 7.50μ*** spherical effect could be achieved(sharp edge angles of particles are rounded off and reshaped)when the processing time is over 30 *** relationship between average diameter(d)and pro-cessing time can be described by the exponential decay model,which provides a good interpretation for the process of *** relationship between them can be expressed by the equation d=1.87406exp(-x/8.92718)+*** proposed method could readily enable large-scale production of spherical tungsten powder.

关键词： Tungsten powder Modification average diameter Powder metallurgy

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Electrospinning of polycarbonate urethane biomaterials

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Frontiers of Chemical Science and Engineering 2011年第1期5卷 11-18页

作者： Yakai FENG Fanru MENG Ruofang XIAO Haiyang ZHAO Jintang GUO School of Chemical Engineering and Technology Tianjin UniversityTianjin 300072China

Polycarbonate urethane(PCU)nano-fibers were fabricated via electrospinning using N,Ndimethylformamide(DMF)and tetrahydrofuran(THF)as the mixed *** effect of volume ratios of DMF and THF in the mixed solvent on the fiber structures was *** results show that nano-fibers with a narrow diameter distribution and a few defects were obtained when mixed solvent with the appropriate volume ratio of DMF and THF as 1∶*** the proportion of DMF was more than 75%in the mixed solvent,it was easy to form many beaded *** applied voltage in the electrospinning process has a significant influence on the morphology of *** the electric voltage was set between 22 and 32 kV,the average diameters of the fibers were found between 420 and 570 *** electron microscopy(SEM)images showed that fiber diameter and structural morphology of the electrospun PCU membranes are a function of the polymer solution *** the concentration of PCU solution was 6.0 wt-%,a beaded-fiber microstructure was *** increasing the concentration of PCU solutions above 6.0 wt-%,beaded fiber decreased and finally ***,when the PCU concentration was over 14.0 wt-%,the average diameter of fibers became large,closed to 2μm,because of the high solution *** average diameter of nanofibers increased linearly with increasing the volume flow rate of the PCU solution(10.0 wt-%)when the applied voltagewas 24 *** results show that the morphology of PCU fibers could be controlled by electrospinning parameters,such as solution concentration,electric voltage and flow rate.

关键词： electrospinning polycarbonate urethane process parameter average diameter morphology

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Microscopic Structure of Rabbit Hair

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Agricultural Science & Technology 2012年第12期13卷 2585-2588,2606页

作者：郭天芬王欣荣李维红牛春娥中国农业科学院兰州畜牧与兽药研究所甘肃兰州730050 农业部动物毛皮及制品质量监督检验测试中心甘肃兰州730050 甘肃农业大学甘肃兰州730050

[Objective] The paper was to explore the microscopic structure of rabbit hair. [Method] Single rabbit hair with typical features was selected to observe its mi- croscopic structure from tip to root, and its fiber diameter was also measured. [Result] The rabbit hair tip was constituted by scale layer and cortical layer, without medullary layer; the middle part was generally constituted by scale layer, cortical layer and medullary layer; the root had no medullary layer, and the scale layer was wheatear-shaped. This was the property of rabbit hair, which could be used for comparative studies with other animal fiber and species identification. Rabbit hair had developed medullary layer, and fiber diameter was positively related to column number of medullary cavity. The hair generally was single column, and coarse hair was multi-column. Single rabbit hair was the finest in the tip, coarse in the middle and tapering in the root. The diameter difference of various parts was large, and the ex- ternal growth characteristics was spindle-shaped. [Conclusion] Using biological micro- scope method to identify different animal fur and product species is more objective and simple.

关键词： Rabbit Hair Microscopic structure average diameter

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