Silicon boride synthesis essay - Michigan Media House
08/12/1992 · The metal boride powder is produced by ..
SUBSTANCE: invention relates to structural materials operating in conditions of high thermal load and oxidative medium, and can be used in chemical and metallurgical industry, as well as aircraft engineering. The method involves making a carbon-plastic workpiece based on carbon fibre and thermoreactive binder, thermal treatment thereof until formation of a coke matrix reinforced with carbon fibres, subsequent compacting of the coke matrix via saturation with pyrolytic carbon and silicon impregnation. Saturation with pyrolytic carbon is carried out until achieving intermediate density of the carbon workpiece of 78-87% of the maximum apparent density of the carbon material, after which preliminary silicon impregnation at temperature 1500-1650°C and residual pressure 1-36 mm Hg is carried out, with subsequent distillation of free Si at temperature 1800-1850°C and residual pressure 1-36 mm Hg, and the material is then impregnated with coke binder, carbonised and subjected to final silicon impregnation using a vapour-phase technique.
Silicon boride | Boron | Mediander | Topics
SUBSTANCE: invention can be used in chemical industry and nanotechnology. The nano-film or nano-thread is obtained by depositing on a base - fluoroplastic fibre or film - a layer of boron or silicon with nano-thickness, which is then treated in carbon monoxide gas in the presence of coal or soot at temperature of 1400-1500°C. A silicon layer or a boron layer is the deposited on the formed layer of boron carbide or silicon carbide, respectively. The formed composition is held in a vacuum or in an atmosphere of an inert gas at temperature of 1400-1500°C and then at the same temperature in carbon monoxide gas in the presence of coal or soot. The base used can be corundum fibre or film.
Inorganic Chemistry (ACS Publications)
AB - Single-crystal iron silicon boron (Fe5Si2B) and iron boride (Fe3B) nanowires were synthesized by a chemical vapor deposition (CVD) method on either silicon dioxide (SiO2) on silicon (Si) or Si substrates without introducing any catalysts. FeI2 and BI3 were used as precursors. The typical size of the nanowires is about 5-50 nm in width and 1-20 μm in length. Different kinds of Fe-Si-B and Fe-B structures were synthesized by adjusting the ratio of FeI2 vapor to BI3 vapor. Single-crystal Fe5Si2B nanowires formed when the FeI2 sublimator temperature was kept in the range of 540-570 °C. If the FeI2 sublimator temperature was adjusted in the range of 430-470 °C, single-crystal Fe3B nanowires were produced. Fe3B nanowires grow from polycrystalline Fe 5SiB2 particles, while Fe5Si2B nanowires grow out of the Fe5Si2B layers, which are attached to triangle shaped FeSi particles. Both the ratio of FeI2 vapor to BI3 vapor and the formation of the particles (Fe 5SiB2 particles for the growth of Fe3B nanowires, FeSi particles for the growth of Fe5Si2B nanowires) are critical for the growth of Fe3B and Fe 5Si2B nanowires. The correct FeI2 vapor to BI3 vapor ratio assures the desired phase form, while the particles provide preferential sites for adsorption and nucleation of Fe3B or Fe5Si2B molecules. Fe3B or Fe 5Si2B nanowires grow due to the preferred growth direction of 〈110〉.