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采用直流电弧等离子体,在Ar气氛下热解甲烷,制备了粒度在5—50纳米范围内变化的高纯度纳米炭黑。并用透射电镜和扫描电镜观察炭黑的颗粒形貌、大小与分布。 相似文献
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直流电弧等离子体制备TiN纳米粉末的研究 总被引:6,自引:0,他引:6
采用直流电弧等离子体蒸发-冷凝法制备出了粒径可控的高纯所化钛纳米粉末。探讨了等离子体条件下氮经反应过程和影响TiN粉末粒度的关键工艺参数。研究表明,高温氮等离子体条件下存在着大量的高活性基团,它们参与也氮化反应,提高了氮化反应活性。 相似文献
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采用直流电弧等离子体蒸发-凝聚法制备了高纯氮化铝纳米粉末,粉末的平均晶粒度为50nm,纯度大于98%。借助X射线光电子能谱、化学分析和差热失重等测试手段,探索了AIN纳米粉末的表面化学组成和氧化特性,研究结果表明,AIN纳米粉末易吸湿氧化,大大降低了其纯度。AIN纳米粉末表面的氧是以两种状态即物理吸附态和化合态存在。 相似文献
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纳米铝粉对硝胺炸药热分解催化性能的影响 总被引:3,自引:1,他引:2
采用直流电弧等离子体蒸发法制备了高纯度的纳米铝粉,并用比表面积分析仪和扫描电子显微镜(SEM)对样品进行了表征.将纳米铝粉与硝胺炸药HMX和RDX用研磨混合法制成混合粒子,用DSC对单质HMX和RDX炸药以及纳米铝粉/硝胺炸药混合物进行催化特性测试,并对样品的热分解动力学和热力学参数进行了计算和对比.结果表明,加入纳米铝粉后,HMX和RDX在不同升温速率(2、5、10、20 K/min)下的放热峰峰温降低,活化能分别降低15和16 kJ/mol,热力学参数都有明显变化.纳米铝粉对HMX和RDX有明显的热分解催化作用. 相似文献
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Cheng Wang Jiawen Zhou Ming Song Zhongshan Lu Xianhui Chen Yan Zheng Weidong Xia 《Journal of the American Ceramic Society》2021,104(8):3883-3894
It remains a significant challenge for the scalable production of ultrafine silicon carbide (SiC) nanoparticles with sizes smaller than 10 nm. In this work, a novel process based on atmospheric nonthermal arc plasma was proposed for the continuous synthesis of ultrafine SiC nanoparticles. This low-cost and scalable technique allows preparation of SiC nanoparticles with small size (5–9 nm) and narrow size distribution via hexamethyldisilane (HMDS) decomposition in an argon/hydrogen plasma environment. The as-synthesized products were carbon-rich β-SiC nanoparticles with plentiful functional groups on the surface. The addition of hydrogen in plasma gas can tune the product characteristics, such as decreasing particle size, improving crystallinity, and reducing carbon and oxygen contents. Moreover, the as-prepared β-SiC nanoparticles had a high band gap (around 2.5 eV), and their photoluminescence peak showed an obvious blueshift relative to that of bulk β-SiC, which was mainly attributed to the quantum confinement effect induced by their ultrafine size. According to the spectral information of arc plasma, the formation of SiC nanoparticles in the plasma was discussed. 相似文献
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The paper presents mathematical models and experimental results concerning limited heating with plasma arc of semi-finished products with hard crust in view of their roughing by splintering, extracting of iron from ilmenitic deposits by the plasma jet procedure and production of nanoparticles by thermal decomposition of iron pentacarbonile in the argon plasma jet. 相似文献
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Teguh E. SaraswatiTakafumi Matsuda Akihisa OginoMasaaki Nagatsu 《Diamond and Related Materials》2011,20(3):359-363
The graphite encapsulated iron nanoparticles were fabricated by using arc discharge method. The synthesized nanoparticles were pre-treated by an inductively-coupled RF Ar plasma and then post-treated by NH3 plasma under various gas pressures and treatment times. Analyses of XPS spectra have been carried out to study the effect of the plasma treatment on the surface modification of nitrogen-containing groups. The morphological changes of the particles surface by plasma treatment have also been analyzed by using HR-TEM. Present results show that the highest values of N/C atomic ratio of 5.4 % is obtained by applying 10 min of Ar plasma pre-treatment and 2 min of NH3 plasma post-treatment conducted in RF power of 80 W and gas pressure of 50 Pa. 相似文献
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R. K. Tyagi R. S. Pandey A. Kumar 《Theoretical Foundations of Chemical Engineering》2012,46(5):508-514
In this paper the effect of different parameters like magnetic field, homogenous direct-current electric field, shear scale length, temperature anisotropy, inhomogeneity in direct-current electric field and density gradient on ions velocity is discussed. A mathematical model for ions/micron size particles velocity is discussed and its values are calculated by taking experimental parameters and by applying computer technique. A model of plasma spray machine is also suggested, which contains plasma production with velocity shear instability in laboratory, powder injection and mass and momentum transfers between particles. The coating process by means of velocity shear instability in plasma has possibility to spray hard and arduous material (alloy) with minimum defects and maximum technical and economic efficiency. 相似文献
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《Ceramics International》2017,43(16):13670-13676
Nickel oxide nanoparticles with an average size of between 28 and 62 nm were fabricated by electric arc discharge method. The electric currents of 10, 100, 200, 300 and 400 A and oxygen pressures of 1, 2 and 3 atm. were tested. High yield production was observed for the samples prepared at low arc current. The samples were characterized using XRD and FESEM measurements. XRD results showed that the samples were pure and single phase of nickel oxide with cubic structure. The produced nanoparticles were cubic shaped and the average particle sizes increased by increasing the arc pressure, but decreased by increasing the arc current and their size distributions were uniform. The magnetic measurements confirmed a soft ferromagnetic behavior for the nickel oxide nanoparticles at low field region but the hysteresis loop tended to be antiferromagnetic like for the higher fields. By decreasing the particle size from 62 nm, the coercivity (Hc) increased but decreased when the particle size was less than about 57 nm. Such magnetic behavior which can be common for antiferromagnetic nanoparticles was interpreted based on a core-shell model. 相似文献
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S. Hinokuma K. Murakami K. Uemura M. Matsuda K. Ikeue N. Tsukahara M. Machida 《Topics in Catalysis》2009,52(13-20):2108-2111
Direct deposition of Pt and Pd nanoparticles onto γ-Al2O3 powders was studied by using a pulsed arc plasma process under vacuum to use them as an automotive catalyst. As deposited Pt catalyst exhibited a higher metal dispersion and thus a higher catalytic activity for CO oxidation, compared to the conventional Pt/Al2O3 prepared by wet impregnation. In contrast, Pd/Al2O3 prepared by the arc plasma method was less active because of its metallic state of Pd with a lower dispersion. A weak interaction between precious metals and γ-Al2O3 is not enough for thermal stabilization of as deposited nanoparticles during ageing in a stream of 10% H2O in air at 900 °C. 相似文献
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Xiuqi Fang Carles Corbella Denis B.Zolotukhin Michael Keidar 《Frontiers of Chemical Science and Engineering》2019,13(2):350-359
Graphene platelet networks (GPNs) were deposited onto silicon substrates by means of anodic arc discharge ignited between two graphite electrodes.Substrate temperature and pressure of helium atmosphere were optimized for the production of the carbon nanomaterials.The samples were modified or destroyed with different methods to mimic typical environments responsible of severe surface degradation.The emulated conditions were performed by four surface treatments,namely thermal oxidation,substrate overheating,exposition to glow discharge,and metal coating due to arc plasma.In the next step,the samples were regenerated on the same substrates with identical deposition technique.Damaging and re-growth of GPN samples were systematically characterized by scanning electron microscopy and Raman spectroscopy.The full regeneration of the structural and morphological properties of the samples has proven that this healing method by arc plasma is adequate for restoring the functionality of2D nanostructures exposed to harsh environments. 相似文献
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《Ceramics International》2016,42(15):16469-16473
In this study, Si/SiC nanocomposites were synthesized by non-transferred arc thermal plasma processing of micron-sized SiC powder. First, micron-sized SiC was synthesized by solid-state method where waste silicon (Si) and activated carbon (C) powder were used as precursor materials. The effect of Si/C mole ratio and solid-state synthesis temperature on structural and phase formation of SiC was investigated. Diffraction pattern confirmed the formation of SiC at 1300 °C. High C content was required for the synthesis of pure SiC as Si remained unreacted when Si/C mole ratio was below 1/1.5. Highly agglomerated micron-size (0.6–10 µm) SiC particles were formed after solid-state synthesis. Thermal plasma processing of solid-state synthesized micron-sized SiC resulted into the formation of uniformly dispersed (20–60 nm) Si/SiC nanoparticles. It was proposed that Si/SiC nanocomposites were formed due to partial decomposition of SiC during high temperature plasma processing. The formation of Si/SiC nanoparticles from micron-sized SiC was resulted from dissociation of grains from their grain boundary during plasma processing. 相似文献
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A simple and efficient method for preparing graphitic carbon encapsulated rare-earth metal (lanthanum and europium) nanoparticles was explored. The samples were obtained by carbonizing a mixture of soluble metallic salt and dextrose at 773 K, and subsequently annealing the mixture at 1273 K in a nitrogen atmosphere. The annealed samples were studied by X-ray diffraction, high-resolution transmission electron microscopy, laser particle-size analysis and Raman spectroscopy. The results indicated that the samples prepared in our method were rather different from those described in previous publications. In these publications, the lanthanum (La) was encapsulated in the form of carbide and the europium (Eu) was not wrapped in graphitic carbon when the electric arc discharge method was used, while in our method, the rare-earth metal (La and Eu) nanoparticles were coated by graphitic carbon layers. Using the strategy mentioned above, which exploits a simple route to synthesize carbon encapsulated rare-earth metal nanoparticles with high yield, as much as 12-20 g of product can be prepared at one time. This strategy would be a prospective way for the application of rare-earth metal-carbon nanocapsules. A possible mechanism for the formation of the core-shell structure of these nanoparticles is discussed briefly. 相似文献