نتایج جستجو برای: boron carbide
تعداد نتایج: 26716 فیلتر نتایج به سال:
The study presents a possible mechanism to produce carbides and diborides of transition metals, such as titanium, vanadium, chromium zirconium. carbothermal synthesis metal has defined the direct dependence between thermodynamic stability oxides temperature range reduction onset (the stronger oxide, higher value is). It reaches 2000-2100, 1500-1600, 1300-1400 2100-2200°C for TiC, VC 0,88 , Cr 3...
In order to simulate neutron shields, MCNP5 calculation code was used and three types of homogeneous and separated shield multilayer arrangement, irradiated with 241Am-Be neutron sources were investigated. In these shields, the polyethylene (C2H4) and polystyrene (C8H8) were used as moderator material, and the boron carbide (B4C), as a thermal neutron absorber material and stainless steel as a ...
The paper presents the results of experimental studies on implementation electric arc synthesis boron carbide using carbon with different morphology and origin as a feedstock: fibers, flake graphite, obtained by pyrolysis plant waste, namely, pine sawdust cedar nuts husks. A feature method used is its an original plasma reactor atmospheric air working gas medium. Oxidation feedstock products in...
Sintering temperature and composition are two important factors that affect the properties of ceramic materials. In this study, effects sintering temperature, dwelling time, intermediate dwell, B4C content on density, microstructure, elastic dense SiC ceramics were investigated. 1.5 wt% C 0.25 or 0.5 added to which was spark plasma sintered (SPS) at 1900 °C, 1950 2000 °C under a pressure 50 MPa...
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...
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 ...
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