About Boron Carbide Powder
Boron carbide powder is hard, black, and shiny. Its hardness is lower than industrial diamond but higher than silicon carbide. Boron carbide is less fragile than most pottery. It has a large thermal neutron capture cross-section, and strong chemical resistance. It is not subject to attack by hot hydrogen fluoride and nitric acid. It is soluble in molten alkali and insoluble in water and acid. The relative density (D204) is 2.508 to 2.512. The melting point is 2350 ℃. The boiling point is 3500 ℃.
Physicochemical Properties of Boron Carbide Powder
Boron carbide does not react with acid and alkali solution and has high chemical potential. It has the properties of neutron absorption, wear-resistance, and semiconductor conductivity. It is one of the most stable substances to acids and is stable in all concentrated or dilute acid or alkaline water solutions. Boron carbide is basically stable under 800℃ in the air environment.
When some transition metals and their carbides coexist, they have special stability. The transition metals ⅳ, ⅴ, and ⅵ in the periodic table react strongly with boron carbide powder to form metal borides at 1000 ~ 1100℃. At higher reaction temperatures, it has been reported that boron carbide tends to nitride or react with transition metal oxides to form corresponding boron nitride and borides, which are mainly rare earth and alkaline earth metal hexaborides.
It has a Mohs hardness of about 9.5 and is the third hardest substance known after diamond and cubic boron nitride, which is harder than silicon carbide.
Due to the preparation method, boron carbide is easy to form carbon defects, resulting in a wide range of boron to carbon ratio changes without affecting the crystal structure, which often leads to the degradation of its physical and chemical properties. Such defects are difficult to be resolved by powder diffraction and often require chemical titration and energy loss spectrum.
|Boron Carbide Powder Properties|
|Other Names||B4C, B4C powder, black diamond, boron carbide powder|
|Appearance||gray black powder|
|Solubility in H2O||insoluble|
Boron carbide is suitable for hard materials of drilling, grinding, and polishing, such as hard alloy, ceramic wear parts including wear plate, pump parts, bearings, faucet, nozzle, valve parts engineering ceramics, biological ceramics, nuclear reactor pellet, lightweight body armor materials applications. Specifically,
1. Used to control nuclear fission. Boron carbide can absorb large amounts of neutrons without forming any radioactive isotopes, making it an ideal neutron absorber for nuclear power plants, where neutron absorbers control the rate of nuclear fission.
2. As abrasive materials. Boron carbide has been used as a coarse abrasive material for a long time. Because of its high melting point, it is not easy to cast into artifacts, but by melting at high temperatures, it can be machined into simple shapes. Used for grinding, drilling, and polishing of hard materials such as hard alloy and precious stone.
3. For coating coatings. Boron carbide can also be used as a ceramic coating for warships and helicopters. It is lightweight and has the ability to resist armor-piercing bullets penetrating the hot-pressed coating as a whole.
4. For the nozzle. It is used in the arms industry to make gun nozzles. Boron carbide is extremely hard and wear-resistant, does not react with acid and alkali, has high/low-temperature resistance, high-pressure resistance, density ≥2.46g/cm3; Microhardness ≥ 3500kGF /mm2, bending strength ≥400MPa, melting point is 2450℃. Because the boron carbide nozzle has the characteristics of wear resistance and high hardness, the boron carbide sandblasting nozzle will gradually replace the known carbide/tungsten steel and silicon carbide, silicon nitride, alumina, zirconia, and other materials of the sandblasting nozzle.
5. Others. Boron carbide is also used in the manufacture of metal borides and smelting of sodium boron, boron alloys, and special welding.