A novel SiC?ZrB2 coating was prepared using a two-step technique by slurry-sintering and chemical vapor reaction on carbon/carbon (C/C) composites. The SiC?ZrB2 coating was composed of the scattered ZrB2 phase and the...A novel SiC?ZrB2 coating was prepared using a two-step technique by slurry-sintering and chemical vapor reaction on carbon/carbon (C/C) composites. The SiC?ZrB2 coating was composed of the scattered ZrB2 phase and the continuous SiC phase. It was observed that a good adhesion was built between the coating and the C/C composites. The SiC?ZrB2 coating samples exhibited a better ablation resistance in comparison with the uncoated C/C composites. The SiO2?ZrO2 barrier layer, the heat dissipation of the gaseous products and the pinning effect of ZrO2 all contributed to the good ablation resistance of the SiC?ZrB2 coated composites.展开更多
Taking into account both the intrinsic curvature and Zeeman effects, persistent currents in a multi-walled carbon nanotorus are explored by using a supercell method, within the tight-binding formalism. It is shown tha...Taking into account both the intrinsic curvature and Zeeman effects, persistent currents in a multi-walled carbon nanotorus are explored by using a supercell method, within the tight-binding formalism. It is shown that in the absence of the Zeeman effect, the intrinsic curvature induces some dramatic changes in energy spectra and thus changes in the shape of the flux-dependent current. A paramagnetism diamagnetism transition is observed. With consideration of the Zeeman splitting energy, the period of persistent current is destroyed, and a diamagnetism-paramagnetism transition is obtained at high magnetic field. In addition, we further explore the effect of external electric field energy （Eef） on persistent current, indicating that it changes unmonotonously with Eef.展开更多
基金Projects(51404041,51304249)supported by the National Natural Science Foundation of ChinaProject(2015JJ3016)supported by the Natural Science Foundation of Hunan Province,China+1 种基金Project(2011CB605801)supported by the National Basic Research Program of ChinaProject supported by the State Key Laboratory for Powder Metallurgy Foundation,Central South University,Changsha,China
文摘A novel SiC?ZrB2 coating was prepared using a two-step technique by slurry-sintering and chemical vapor reaction on carbon/carbon (C/C) composites. The SiC?ZrB2 coating was composed of the scattered ZrB2 phase and the continuous SiC phase. It was observed that a good adhesion was built between the coating and the C/C composites. The SiC?ZrB2 coating samples exhibited a better ablation resistance in comparison with the uncoated C/C composites. The SiO2?ZrO2 barrier layer, the heat dissipation of the gaseous products and the pinning effect of ZrO2 all contributed to the good ablation resistance of the SiC?ZrB2 coated composites.
基金Project supported by the National Natural Science Foundation of China (Grant No. 10674113)Program for New Century Excellent Talents in University of China (Grant No. NCET-06-0707)+2 种基金Foundation for the Author of National Excellent Doctoral Dissertation of China (Grant No. 200726)Scientific Research Fund of Hunan Provincial Education Department of China (Grant No. 06A071)partially by Hunan Provincial Innovation Foundation For Postgraduate (Grant No. S2008yjscx06)
文摘Taking into account both the intrinsic curvature and Zeeman effects, persistent currents in a multi-walled carbon nanotorus are explored by using a supercell method, within the tight-binding formalism. It is shown that in the absence of the Zeeman effect, the intrinsic curvature induces some dramatic changes in energy spectra and thus changes in the shape of the flux-dependent current. A paramagnetism diamagnetism transition is observed. With consideration of the Zeeman splitting energy, the period of persistent current is destroyed, and a diamagnetism-paramagnetism transition is obtained at high magnetic field. In addition, we further explore the effect of external electric field energy （Eef） on persistent current, indicating that it changes unmonotonously with Eef.
