Synthesis and typical properties of boron carbide

The commonly used method for the industrial synthesis of B4C powder is to reduce boric anhydride with excess carbon:

2B2O3+7C→B4+6CO↑

The synthesis reaction can be carried out in a muffle furnace or an electric arc furnace. When synthesizing in a resistance furnace, heating the mixture of boric anhydride B2O3 and carbon C at a temperature lower than the decomposition temperature of B4C to obtain B4C (sometimes containing 1%-2% of free B) is a better synthesis method. During synthesis in an electric arc furnace, the B4C powder decomposes into carbon-rich phase and boron at about 2200°C due to the high arc temperature. Sometimes it will volatilize, resulting in a large amount of free C (20%-30%) in the reaction product, so the quality of the obtained B4C is slightly worse.

When synthesizing B4C with an electric arc furnace, boric acid (content greater than 92%), artificial graphite (fixed carbon greater than 95%) and petroleum coke (fixed carbon greater than 85%) are usually used as raw materials, and the theoretical amount is calculated according to the reaction formula. The theoretical amount is about 2% higher. Artificial graphite powder and petroleum coke each account for 50% of the total carbon addition, which is 3%-4% higher than the theoretical amount. The three raw materials prepared are mixed in a ball mill and added to the arc, and reduced and carbonized in a furnace at 1700-2300°C to obtain B4C. Finally, the frit is sorted, washed, crushed, ground, pickled, precipitated, classified, etc., to obtain B4C of various particle sizes.

What is boron carbide?

Boron carbide powder belongs to the trigonal crystal system. There are 12 B atoms and 3 C atoms in the unit cell. The connected stereodiagonal configuration of C atoms in the unit cell is in an active state, and can be replaced by B atoms to form a replacement solid solution, and may leave the crystal lattice to form defective high boron compounds.

The molecular weight of B4C is 52.25, C21.74% and B78.25%, usually gray-black, density 2.519g/cm3, Mohs hardness 9.35, microhardness about 49GPa, second only to diamond and cubic boron nitride, therefore, B4C powder has a very high grinding ability, and its grinding efficiency can reach 60%-70% of diamond, which is higher than 50% of SiC, which is 1-2 times that of corundum.

The melting point of B4C powder is 2450°C (decomposition). The expansion coefficient at 1000°C is 4.5×10-6°C-1. The thermal conductivity is 121.4W/m·k at 100°C and 62.79W/m·k at 700°C. B4C powder is mainly used as an abrasive, and hot-pressed B4C products can be used as wear-resistant and heat-resistant parts. B4C is mainly used as an additive in the refractory industry, such as being added to carbon-junction refractories as an antioxidant. Unshaped materials improve the strength and corrosion resistance of the car body.

Overview of boron carbide B4C powder

Boron carbide has the characteristics of low density, high strength, good high temperature stability, and good chemical stability. Therefore, it is widely used in wear-resistant materials, ceramic reinforcement phases, especially lightweight armor, reactor neutron absorbers, etc. In addition, compared with diamond and cubic boron nitride, boron carbide is easy to manufacture and low in cost, so it is more widely used. In some places, it can replace expensive diamonds, usually used for polishing, grinding, drilling, etc.

B4C powder has the characteristics of high purity, small particle size distribution, and large specific surface area. B4C powder is a synthetic superhard material with a hardness of 9.46; a microhardness of 56-6200Kg/mm2, a ratio of 252g/cm3, and a melting point of 2250 degrees Celsius.

Chemical characteristics, non-magnetic, high temperature and low temperature resistance, strong acid, strong alkali. In addition, boron carbide can effectively absorb neutrons, does not emit gamma rays harmful to the human body, and does not form secondary radiation pollution. The hardness is only lower than diamond. Boron carbide is one of the most stable substances to acid, and it is stable in all concentrated or dilute acid or alkali aqueous solutions. Boron carbide is basically stable below 800°C in an air environment. The boron oxide formed by high-temperature oxidation is lost in the gas phase, making it unstable, and oxidizing to generate carbon dioxide and boron trioxide.

Boron carbide can absorb a large number of neutrons without forming any radioactive isotopes. It is an ideal neutron absorber for nuclear power plants. Neutron absorbers mainly control the rate of nuclear fission. Boron carbide is used in nuclear reactors. Made into controllable rods, but sometimes made into powder due to increased surface area.

Application of boron carbide B4C powder

Control nuclear fission: can absorb a large number of neutrons without forming any radioactive isotopes. It is an ideal neutron absorber for nuclear power plants. Neutron absorbers mainly control the rate of nuclear fission. Boron is mainly made into controllable rods in the field of nuclear reactors, but sometimes it is made into powder due to the increase in surface area.

Abrasive: Because boron carbide has been used as a coarse abrasive for a long time. Because of its high melting point, it is not easy to cast into artificial products, but the powder can be smelted into simple shapes. high temperature. Used for grinding, grinding, drilling and polishing hard materials such as cemented carbide and gemstones.

Coating paint: Boron carbide can also be used as a ceramic coating for warships and helicopters. Light in weight, it can resist the penetration of armor-piercing projectiles through the hot-press coating to form an overall defense layer.

Nozzle: Boron carbide can be used as a spray gun nozzle in the ordnance industry. Boron carbide is extremely hard and wear-resistant, does not react with acid and alkali, is resistant to high temperature/low temperature, and is resistant to high pressure. Boron carbide is also used to make metal borides and smelt sodium-boron, boron alloys and special welding.

Price of boron carbide B4C powder

The price of boron carbide varies randomly with factors such as production costs, transportation costs, international conditions, exchange rates, and market supply and demand. Tanki New Materials Co.,Ltd. aims to help various industries and chemical wholesalers find high-quality, low-cost nanomaterials and chemicals by providing a full set of customized services. If you are looking for boron carbide, please feel free to contact us for the latest boron carbide prices.

Supplier of Boron Carbide B4C Powder

As a global boron carbide supplier, Tanki New Materials Co., Ltd. has extensive experience in the performance, application and cost-effective manufacturing of advanced engineering materials. The company has successfully developed a series of powder materials (including chromium carbide, aluminum carbide, titanium carbide, etc.), high-purity targets, functional ceramics and structural devices, and provides OEM services.

Technical parameter of Boron carbide B4C powder
Boron Carbide Nanoparticles (B4C)
Crystal phase: Hexagonal
APS: 45-55nm
SSA: 40-60m²/g
Zeta Potential: -26mV
Bulk density: 0.10g/cm³
Purity: >99%
Color: Black
Making Method: Plasma vapor phase synthesis method