共查询到19条相似文献,搜索用时 62 毫秒
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以氧化铁和无定型硼粉为原料,反应气氛为碳气氛,在1 400℃下利用化学气相沉积法(CVD)制备出氮化硼纳米管。X射线研究表明,对应着六方氮化硼晶面的特征衍射峰非常清晰。采用扫描电子显微镜(SEM)对样品的结构与形貌进行表征,结果表明,样品属于一端开口的竹节状BN纳米管。 相似文献
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本文以三聚氰胺(C3N6H6)为原料,通过高温热分解法成功的制备了氮掺杂碳纳米管(N—CNTs)。据SEM和TEM图像显示,所制备的N—CNTs呈竹节状,并且直径和壁厚统一。利用FTIR图谱分析了N—CNTs的结构和官能团组成。同时,对N—CNTs的发光特性进行了研究,发现样品在蓝紫光范围内具有发光特性,这使得其在光学纳米器件方面具有潜在的应用价值。 相似文献
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Shota Daiki Toshihiro Ishikawa 《International Journal of Applied Ceramic Technology》2023,20(4):2603-2609
Hexagonal boron nitride (h-BN) particles exhibit high thermal conductivity and are promising fillers for resin filling. However, h-BN particles are plate-like particles with thermal anisotropy in the planar and thickness directions. Therefore, their applications are limited due to low thermal conductivity in the direction of the thickness of a resin sheet filled with h-BN particles. In this study, we control the size and thickness of h-BN particles using carbothermal reduction nitridation (CRN), which involves the carbothermic reduction of boric oxide in an N2 gas atmosphere and develop them into resin sheets. In CRN using a CaO promoter, a novel method is developed to control the shape, size, and thickness of h-BN particles. Using h-BN particles grown in the thickness direction, we have successfully provided resin sheets with high thermal conductivity. 相似文献
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Guo-Jun Zhang Yoshihisa Beppu Motohide Ando Jian-Feng Yang Tatsuki Ohji 《Journal of the American Ceramic Society》2002,85(11):2858-2860
This work proposes a new approach, based on the reaction Si3 N4 + 2B2 O3 + 9C → 3SiC + 4BN + 6CO, to synthesize an SiC–BN composite. The composite was prepared by reactive hot pressing (RHP), at 2000°C for 60 min at 30 MPa under an argon atmosphere, following a 60 min hold at 1700°C without applied pressure before reaching the RHP temperature. TG-DTA results showed that a nitrogen atmosphere inhibited denitrification somewhat and retarded the reaction rate. The chemical composition of the obtained material was consistent with theoretical values. FE-SEM observation showed that in situ -formed SiC and BN phases were of spherical morphology with very fine particle size of ∼100 nm. 相似文献
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Jihong Cheng Zhaoqiang Zeng Chongjun Wu Xiaoqing Hu Hezhuo Miao 《Journal of the American Ceramic Society》2001,84(4):887-889
BN–AlN ceramic composites have been successfully fabricated by a novel process referred to as transient plastic phase processing (TPPP). The process used BN as both the reactant phase and the matrix and Al as the transient plastic phase. The products AlN and AlB12 were regarded as the reinforcing phases. With the addition of Al powder in BN, both the mechanical and thermal properties were improved. Relatively high green density (2.03 g/cm3 , 82.0% of theoretical density (TD)) and as-sintered density (2.18 g/cm3 , 92.6%TD), high bending strength (106 MPa), and high thermal conductivity (72 W/(m·K)) were attained for one kind of BN–AlN composite. A low thermal expansion coefficient of 2.0 × 10− 6 /K was also achieved. 相似文献
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Surface morphologies of the films of poly [styrene-b-(ethylene-co-butene)-b-styrene] (SEBS) have been studied by using tapping-mode atomic force microscopy (TM-AFM). The films of block copolymer were prepared both by spin-coating on mica and by solvent-casting on different solution surfaces. For spin-coating samples, the effect of solution concentration, solvent, and annealing temperature are investigated. It is shown that changing the concentration of the solution makes no difference on the morphology of the film of the block copolymer. The microstructures are quite stable during thermal annealing; only the size of the domains changes toward the equilibrium configuration. However, solvent annealing can notably change the microstructures. When different selective solvents are used for film spin-coating, different morphologies can be obtained and explained by the different solubility parameters of the solvents. As expected, significant different morphologies in the top and the bottom surfaces of the casting films were observed. The images of the top surfaces reveal cylinder microdomains, while those of the bottom surfaces were spherical morphologies. 相似文献
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K.F. McCarty P.B. Mirkarimi D.L. Medlin T.A. Friedmann J.C. Barbour 《Diamond and Related Materials》1996,5(12):1519-1526
The sharp threshold in substrate temperature below which cubic boron nitride (cBN) cannot be formed in energetic film-deposition processes was investigated. We found that cBN could be synthesized below the threshold temperature on top of cBN that had been previously formed above the threshold temperature. That the initial nucleation of cBN is more strongly dependent on temperature than its subsequent growth is suggested. How the structure of the sp2-bonded BN that accompanied cBN growth changed with temperature was also investigated. Lowering the substrate temperature decreased the local ordering within the graphitic planes, and below the threshold temperature the separation of the graphitic planes increased dramatically. How these structural changes may influence the nucleation of cBN is discussed. 相似文献
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Dmitri Golberg Yoshio Bando Yang Huang Zhi Xu Xianlong Wei Laure Bourgeois Ming-Sheng Wang Haibo Zeng Jing Lin Chunyi Zhi 《Israel journal of chemistry》2010,50(4):405-416
Herein the recent experiments performed by the authors on fabricated multi-walled BN nanotubes and monoatomic BN graphene-like nanosheets are reviewed. The results are presented in several sections, namely: (i) method for high-yield synthesis of thin, defect-free BN nanotubes of only a few-layers, with external diameters below 10 nm; (ii) verification of BN nanotube piezoelectrical behavior and its electrically-induced thermal decomposition under combined resistive heating and electrical charging in a transmission electron microscope; (iii) the first direct measurements of the true tensile strength and Young’s modulus of BN nanotubes, using newly developed nanotensile tests inside an electron microscope; the measured values were found to be ∼30 GPa and ∼900 GPa, respectively; and (iv) diverse kinetic processes taking place within the prepared monoatomic BN sheets (so-called “white graphenes”) affiliated with intensive knock-on B and N atom displacements under high energy electron beam irradiation in an aberration-corrected medium-voltage high-resolution transmission electron microscope. 相似文献