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Boron carbide was discovered in the 19th century as a by-product of reactions involving metal borides, but its chemical formula was unknown. It was not until the 1930s that the chemical composition was estimated as B 4 C. [4] Controversy remained as to whether or not the material had this exact 4:1 stoichiometry, as, in practice the material is always slightly carbon-deficient with regard to ...
ZrO 2 and HfO 2 can be dispersed in boron carbide polymeric precursors prior to reaction. Heating the reaction mixture to 1500 °C results in the in situ generation of boron carbide and carbon, and the reduction of ZrO 2 to ZrB 2 soon follows. [20] The polymer must be stable, processable, and contain boron and carbon to be useful for the reaction.
Boron carbide, B 4 C, on the other hand, has an unusual structure which includes icosahedral boron units linked by carbon atoms. In this respect boron carbide is similar to the boron rich borides. Both silicon carbide (also known as carborundum) and boron carbide are very hard materials and refractory. Both materials are important industrially.
The emissivity of the surface of a material is its effectiveness in emitting energy as thermal radiation. Thermal radiation is electromagnetic radiation that most commonly includes both visible radiation (light) and infrared radiation, which is not visible to human eyes.
Boriding can be achieved in several ways, but commonly the metal piece is packed with a boriding mixture and heating at 900 °C. Typical boriding mixture consists of boron carbide powder diluted with other refractory materials.
The wide absorption spectrum of boron also makes it suitable as a neutron shield. The mechanical properties of boron in its elementary form are unsuitable, and therefore alloys or compounds have to be used instead. Common choices are high-boron steel and boron carbide. The latter is used as a control rod material in both PWRs and BWRs.
Boron carbide (B 4 C) B 13 C 2. This section is empty. You can help by adding to it. (January 2016) α-tetragonal boron. α-tetragonal boron is a boron-rich ...
Organoboron chemicals have been employed in uses as diverse as boron carbide (see below), a complex very hard ceramic composed of boron-carbon cluster anions and cations, to carboranes, carbon-boron cluster chemistry compounds that can be halogenated to form reactive structures including carborane acid, a superacid.