English Name: boron silicide (b6si); Boron silicide; Silicon boride; Hexaboron silicide
CAS:12008-29-6 [1]
EINECS:234-535-8
Molecular formula: b6si
Molecular weight: 92.952
Relative density: 3.0g/cm3
Melting point: 2200 ℃
Silicon hexaboride Application:
1.B6Si can effectively promote the sintering of boron carbide ceramics and improve the mechanical properties of the material.
2. Because silicon hexaboride has heat resistance and high impact resistance, it is relatively cheap, so it is often used in resin grinding wheels and as the main abrasive. As a P-type high temperature thermoelectric material to replace boron carbide, can be used as a variety of standard abrasive, grinding carbide. It is also used as engineering ceramic materials, sandblasting nozzle, and the manufacture of gas engine blades and other special-shaped sintered parts and seals. Used as an antioxidant for refractories.
Silicon hexaboride terminology: Chemical formula SiB6. Molecular weight 92.95. A black crystal. The relative density is 2.47. Hardness between diamond and ruby. It conducts electricity. Insoluble in water. When heated in chlorine and water vapor, the surface can be oxidized. It can be oxidized directly in boiling nitric acid. Unchanged in molten potassium hydroxide. It breaks down in hot concentrated sulfuric acid. Description: The silicon and boron mixture can be directly heated, the excess silicon is removed with hydrofluoric acid and nitric acid, and then the silicon triboride (B3Si) in the mixture is decomposed with molten potassium hydroxide. The SiB6 crystal structure consists of interconnected icosahedrons (20-hedral polyhedra), icosahedrons (26-hedral polyhedra), and isolated silicon and boron atoms. Due to the size mismatch between silicon and boron atoms, silicon can be substituted for boron in a B12 icohedron until a limiting stoichiometric ratio corresponding to SiB2.89 is reached.
High purity silicon hexaboride process:
The invention is a low-cost and high-purity silicon hexaboride production process, in which boron trioxide and potassium borohydride are pressed into blocks after ball milling, protected by argon gas, and loaded into a vacuum carbon tube furnace, then pumped out and kept at 750℃ for 5 hours; Heat up to 1250℃, continue to hold heat until the pressure in the furnace is slightly positive pressure, and the reduction reaction is completely completed. The mixture of monomer boron and potassium hydroxide in the graphite crucible will be obtained, and the mixture will be heated and cleaned in distilled water to get boron powder. After the boron powder and silicon powder ball grinding mixture, into the autogenous combustion reactor, the reactor is evacuated, the vacuum degree to 1 pa, the power is sent to heat up the tungsten wire, ignite the zirconium powder, and carry out high temperature autogenous combustion combination reaction, the reaction is finished, cooling, impurity removal, and high purity silicon hexaboride is obtained. With boron trioxide and potassium borohydride as raw materials, the raw material cost is relatively low, and the whole process is reasonable and controllable, the purity of the silicon hexaboride produced is 99.5%, which is suitable for industrial production.
