نتایج جستجو برای: boron carbide synthesis
تعداد نتایج: 434147 فیلتر نتایج به سال:
Nanowires of complex morphologies, such as kinked wires, have been recently synthesized and demonstrated for novel devices and applications. However, the effects of these morphologies on thermal transport have not been well studied. Through systematic experimental measurements, we show that single-crystalline, defect-free kinks in boron carbide nanowires can pose a thermal resistance up to ∼30 ...
Aluminum-based metal matrix composite (MMC) materials are used in the design of ground transportation vehicles and aircraft. Compared with conventional, unreinforced alloys, composite materials usually exhibit higher strength, both at ambient and elevated temperatures, as well as good fatigue strength and wear resistance. MMCs could be produced by variety of methods such as Stir cast, Liquid In...
Aberration corrected high angle annular dark field scanning transmission electron microscopy (HAADF-STEM) was employed to study the distribution of barium atoms on the surfaces and in the interiors of boron carbide based nanowires. Barium based dopants, which were used to control the crystal growth, adsorbed to the surfaces of the boron-rich crystals in the form of nanometer-thick surficial fil...
The effect of boron on nitrogenase activity has been studied. When cells were dependent on N(2) fixation, the lack of boron inhibited nitrogenase activity. However, under anaerobic conditions or in the presence of Na-dithionite this effect was not observed. Nitrogenase synthesis was not affected by boron deficiency. Similarly, the heterocyst number was not altered. Examination of boron-deficien...
Herein we report on the synthesis of a new layered ternary carbide, viz. Mo2TiAlC2, that was synthesized by heating an elemental mixture at 1600 oC for 4 h under Ar flow. Its lattice parameters were calculated via Rietveld analysis of powder Xray diffraction patterns to be 2.997 Å and 18.661 Å. High-resolution scanning transmission electron microscopy further showed that this phase is ordered, ...
Three phase boride and carbide ceramics were found to have remarkably high hardness values. Six different compositions produced by hot pressing ternary mixtures of Group IVB transition metal diborides, SiC, B 4 C. Vickers’ at 9.8 N was ~31 GPa for a ceramic containing 70 vol% TiB 2 , 15 C, increasing ~33 equal volume fractions the three constituents. Hardness values ZrB HfB ~30% 20% lower than ...
In the present work, we report a novel design and preparation for the mechanochemical synthesis of calcium carbide-derived carbon (CaC2-CDC) at ambient temperature. Thermodynamic calculations confirmed the possibility of calcium carbide-derived carbon formation by the reaction of calcium carbide with sulfur, iron sulfide and zinc oxide at ambient temperature. The CDCs were synthesized by the ba...
So far, no boron fullerenes were synthesized: more compact sp(3)-bonded clusters are energetically preferred. To circumvent this, metallic clusters have been suggested by Pochet et al. [Phys. Rev. B 83, 081403(R) (2011)] as "seeds" for a possible synthesis which would topologically protect the sp(2) sector of the configuration space. In this paper, we identify a basic pentagonal unit which allo...
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