Boron carbide, also known as Black Diamond, is a kind ofInorganic, chemical formula is B ₄ C, usually gray black powder.It is one of the three hardest materials known (only second to diamond and cubic boron nitride) and is used in tank armor, bullet proof clothing and many industrial applications.itsMohs hardnessAbout 9.5.[2]
It served asmetal boride The by-product of the research was discovered and was not studied scientifically until the 1930s.Boron carbide can be reduced by carbon in electric furnaceBoron trioxideMade.
Boron carbide can absorb a lot of neutrons without forming anyradio isotopeTherefore, it is an ideal neutron absorber in nuclear power plants, which mainly controls the rate of nuclear fission.Boron carbide is mainly made into controllable rod shape in nuclear reactor field, but sometimes it will be made into powder shape because of increasing surface area.
Due to its low density, high strength, high temperature stability andchemical stabilityGood features.stayWear-resistant materialCeramic reinforcement, especially used in light armor, reactor neutron absorber, etc.In addition, compared with diamond and cubic boron nitride, boron carbide is easier to manufacture and cheaper, so it is more widely used. In some places, it can replace expensive diamond, and is commonly used in grinding, grinding, drilling and other aspects.[1]
Chinese name
Boron carbide[4]
Foreign name
Boroncarbide，Tetraboroncarbide
Alias
Tetraboron monocarbide[4]
chemical formula
B₄C[4]
Appearance
Grayish black micro powder
Application
Bullet proof clothing, etc
Regulatory information
This product is not controlled
Nature
Low density, high strength, high temperature stability
Hard black shiny crystals.The hardness is lower than that of industrial diamond, butsilicon carbideHigh.Compared with most pottery, it is less fragile.With large heat energyNeutron capturesection.Strong chemical resistance.Not heatedHydrogen fluorideandnitric acidErosion.Soluble inmeltIt is insoluble in water and acid.relative density(d204)2.508～2.512。Melting point 2350 ℃.The boiling point is 3500 ℃.
Storage
Sealed storage.
purpose
Chemical resistant pottery, wear-resistant tools manufacturing.
Quality Inspection Info Quality Inspection Item Indicator Value
Quality inspection items
Project index value
Content (B4C)
≥90.0%
Total amount of free carbon, boron trioxide and other impurities
It does not react with acid and alkali solutions, and has advanced degreeneutronAbsorption, abrasion resistance and semiconductor conductivity.It is one of the most stable substances for acid and is stable in all concentrated or dilute acid or alkali aqueous solutions.The boron carbide is basically stable below 800 ℃ in the air environment. Because the boron oxide formed by its oxidation at a higher temperature is lost in gas phase, it is unstable and oxidized to formcarbon dioxideandBoron trioxide。
Boron carbide
When there are some transition metals andcarbideWhen they coexist, they have special stability.At 1000~1100 ℃periodic table of ele mentsThe fourth, fifth and sixth transition metals in the middle react strongly with boron carbide powder to formmetal boride 。However, at higher reaction temperatures, literature reports indicate that boron carbide is easily nitrided or reacts with transition metal oxides to form corresponding boron nitride and borides, which are mostly rare earth and alkaline earth metal hexaborides.
itsMohs hardnessAbout 9.5, it is the third hardest material known after diamond and cubic boron nitride, and its hardness is higher than that of silicon carbide.[2-3]
Due to the factors of preparation methods, boron carbide is easy to form carbon defects, leading to the change of boron carbon ratio in a large range without affecting its crystal structure, which often leads to the reduction of its physical and chemical properties.This defect is often difficult to be distinguished by powder diffraction, and often requires chemical titration andEnergy loss spectrumdetermine.
It should be noted that except for BfourIn addition to C, boron carbide materials may have different stoichiometric ratios. At present, the known B: C stoichiometric ratios are 4~10.5.[2]
preparation
Announce
edit
It was originally reported in the Journal of the American Chemical Society that boron carbide was obtained by the reaction of coke and boron oxide in the electric furnace. This preparation method is also used in industrial production at present.
2BtwoOthree+7C=BfourC+6CO
application
Announce
edit
Control nuclear fission
Boron carbide can absorb a large amount ofneutronWithout forming anyradio isotope, so it is in theNuclear power plantHe is an ideal neutron absorber, which mainly controls the rate of nuclear fission.Boron carbide inNuclear reactorIn the field, it is mainly made into controllable rod shape, but sometimes it is made into powder shape because of the need to increase the surface area.
Since boron carbide has been used as coarse sand for a long timeAbrasive material。Because of its high melting point, it is not easy to cast into artificial products, but it can be processed into simple shapes by melting the powder at high temperature.be used forHard alloyGrinding, grinding, drilling and polishing of hard materials such as precious stones.
Coating
Boron carbide can also be used as ceramics for warships and helicopterscoatingIt is light in weight and has the ability to resist the penetration of armor piercing projectiles through the hot pressed coating to form a whole protective layer.
injector
It can be used to manufacture gun nozzles in the ammunition industry.Boron carbide, extremely hard and wear-resistant, non reactive with acid and alkali, high/low temperature resistant, high pressure resistant, density ≥ 2.46g/cmthree;Microhardness≥3500kgf/mmtwo, bending strength ≥ 400MPa, melting point 2450 ℃.
Because boron carbide nozzle has the above characteristics of wear resistance and high hardness, boron carbideSandblastingThe nozzle will gradually replace the known cemented carbide/tungsten steel and silicon carbideSilicon nitride、alumina、ZirconiaAnd other materials.
other
Boron carbide is also used for manufacturing metal borides, smelting boron sodium, boron alloys and special welding.
