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A char layer is the first barrier against the ablation of insulation materials because it is the first to be subjected to thermal-chemical ablation and particle and gas-mechanical erosion. To study the ablation mechanism of the char layer in depth and to develop accurate models of the ablation phenomenon, the structural characteristics of the char layer must be understood. In this work, the structural...
A columnar bamboo/lignite material was prepared by briquetting a mixture of bamboo carbon and lignite. Activated carbons were obtained by carbonizing the material at 500°C for 30min, followed by activation at 850°C for 2h using either steam or a gaseous mixture of ammonia in water with an ammonia concentration of 2.42mass%. The ammonia-activated carbon was soaked in 21.91% ammonia water for 5h and...
Hollow carbon nanofiber@nitrogen-doped porous carbon (HCNF@NPC) core–shell composite, which was carbonized from HCNF@polyaniline, was prepared as an improved high conductive carbon matrix for encapsulating sulfur as a cathode composite material for lithium–sulfur batteries. The prepared HCNF@NPC-S composite with high sulfur content of 77.5wt.% showed an obvious core–shell structure with an NPC layer...
The erosion of a four-direction carbon/carbon composite test piece using a low-velocity, high-particle-concentration two-phase jet was studied by the hot firing test of a small solid rocket motor with an elaborately designed flow path. The linear ablation rates were measured. The ablation surface and microstructure of the carbon/carbon composites were studied by scanning electron microscopy, and the...
Spirit lees was carbonized and then activated by steam and CO 2 to prepare activated carbons. The effect of carbonization temperature, type and amount of activator, activation temperature and time on the pore structure, and the adsorption of methylene blue and iodine were investigated. The gas products during activation were analyzed online to reveal the activation mechanism. Results showed...
Mesoporous carbon spheres with hierarchical foam-like pore structures have been synthesized by a dual-templating strategy using phenolic resol as a carbon source, Pluronic F127 and spherical silica mesocellular foams (Si-MCFs) as the soft and hard template, respectively. The results show that the morphology and mesostructure of the silica template are faithfully replicated. The obtained mesoporous...
ZnO quantum dots (QDs) are anchored on multi-walled carbon nanotubes (MWCNTs) by a wet chemical self-assembling technique. The structure and properties of QDs/MWCNTs are also studied in detail. First, MWCNTs are functionalized with thiol by a series of chemical reactions. Fourier transform infrared spectroscopy is used to verify changes of chemical bonds on MWCNTs. At one time, quantum dots of ZnO...
Vapor grown carbon fibers have been prepared without any catalyst by microwave pyrolysis chemical vapor deposition using CH 4 as source gas and N 2 as carrier gas at 1050–1150°C. Scanning electron microscopy images reveal that vapor grown carbon fibers are made up of sub-fibers which are hexagonal and layer-like carbon. Polarized light images indicate that sub-fibers are formed by...
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