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RISS 인기검색어
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- 저자 : Tian Chengcheng (검색결과 3 건)
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Preparation of layered B4C with high neutron-shielding properties using graphene as template
Li Yang, Li Sanxi,Wang Song,Tian Chengcheng 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.1
In this paper, layered boron carbide (B4C) particles were successfully synthesized by sol-gel-low temperature pyrolysis methodusing boron acid and glycerin as raw materials with self-made reduced graphene oxide (RGO) as additives. The structure ofthe sol-gel condensation product was analyzed by FT-IR. The phase, morphology and particle size of the B4C werecharacterized by XRD, FE-SEM and LPSA. The results showed that boron carbide was rhombic crystal phase, but the surfaceof the particles was wrinkled and more layered. The B4C powders with uniform morphology and some particle sizes less than100 nm were prepared with the RGO content of 0.6%. Testing the neutron-shielding properties of the polypropylene-B4Ccomposites suggested that neutron transmittance with the B4C content of 35 wt% was 94.1% lower (from 70.6% to 4.1%) thanneat polypropylene, and the total macroscopic absorption cross-section was about 18 times larger (from 0.0857 ± 0.0031 cm-1 to1.5521 ± 0.0008 cm-1). The relative density, fracture toughness and hardness of self-made B4C ceramics (sB4C) were higherthan the commercially available B4C ceramics (cB4C). This study provided a new method for the preparation of B4C powderswith excellent neutron absorption properties and good sintering activity.
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Li Yang,Li Sanxi,Wang Song,Tian Chengcheng,Otitoju Tunmise Ayode 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.2
The effect of addition of ethylene glycol (C2H6O2) on the synthesis of crystalline boron carbide (B4C) powder from a condensedboric acid (H3BO3)-glycerin (C3H8O3) product was investigated. Equal molar amount of H3BO3 and glycerin was mixed andsubjected to dehydration-condensation reaction using various amount of ethylene glycol (0 to 40 mol% based on glycerolamount). Then the condensed product was thermally decomposed in air twice to obtain surface carbon-free precursor powder. The crystalline phases and surface functional groups of the material was characterized using XRD, SEM, FTIR and TGA. Addition of ethylene glycol offered a new organic sites and comparatively, reduced pyrolysis temperature from 700 to 650 oC. The complete formation of crystalline B4C powder was achieved at 1475 oC within 2.5 h, which is among the shortest timereported for B4C synthesis
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Xiaoteng Jia,Ce Wang,Danming Chao,Libing He,Hongtao Liu,Tian Zheng,Chengcheng Zhang 한국고분자학회 2011 Macromolecular Research Vol.19 No.11
A novel hyperbranched electroactive azo polyamide containing oligoaniline was synthesized by oxidative coupling polymerization. The detailed characteristics of the obtained polyamide were systematically studied by Fourier transform infrared (FTIR) spectra, nuclear magnetic resonance (^1H NMR) spectroscopy, and gel permeation chromatography (GPC). The thermogravimetric analysis (TGA) revealed a good thermal resistance of the polymer. The photoisomerization process and doping process of the polymer were monitored with ultraviolet-visible spectroscopy. Further, the electrochemical behavior of the polymer was explored by cyclic voltammogram (CV), and the mechanism of electrochemical oxidation process was studied in detail. The polymer in the HCl-doped form possessed much higher dielectric constants compared with that of the similar linear polymer reported before, mainly due to the highly branched three-dimensional molecular architecture and the high content of oligoaniline segments.
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