Boron Carbide

Jai Ganesh · 2024-11-05 17:01:13

Boron Carbide

Gist

Boron carbide, (B4C), is a crystalline compound of boron and carbon. It is an extremely hard, synthetically produced material that is used in abrasive and wear-resistant products, in lightweight composite materials, and in control rods for nuclear power generation.

Boron carbide is also one of the hardest compounds known to us but is not harder than diamond and boron nitride.

Boron carbide (B4C) is the third hardest material known in nature after diamond and boron nitride. It is an expensive and low-density material. Apart from this, it is highly fragile.

Summary

Boron carbide (B4C) is a crystalline compound of boron and carbon. It is an extremely hard, synthetically produced material that is used in abrasive and wear-resistant products, in lightweight composite materials, and in control rods for nuclear power generation.

With a Mohs hardness between 9 and 10, boron carbide is one of the hardest synthetic substances known, being exceeded only by cubic boron nitride and diamond. As an abrasive, it is used in powdered form in the lapping (fine abrading) of metal and ceramic products, though its low oxidation temperature of 400–500° C (750–930° F) makes it unable to withstand the heat of grinding hardened tool steels. Because of its hardness, together with its very low density, it has found application as a reinforcing agent for aluminum in military armour and high-performance bicycles, and its wear resistance has caused it to be employed in sandblasting nozzles and pump seals. A neutron absorber, boron carbide is used in powdered or solidified form to control the rate of fission in nuclear reactors.

Boron carbide is produced by reducing boron oxide with carbon at high temperatures in an electric furnace. After grinding, the black powder is solidified by pressing at temperatures exceeding 2,000° C (3,630° F). Its melting point is approximately 2,350° C (4,260° F).

Details

Boron carbide (B4C) is one of the hardest man-made materials utilized in lots of fields. It is the third hardest chemical compound, ranking after diamond and cubic boron nitride (formula CBN). Boron carbide is a dark black crystal, so it is also called a “black diamond”. This strong material does not exist in nature, and could only be obtained from boron and carbon in a furnace. Boron carbide can be shaped by pressing at temperatures exceeding 2000 Thanks to its hardness and other unique properties, boron carbide has significant applications in a variety of industries. Boron carbide, with a combination of special properties, is now manufactured in large quantities. It was discovered in the mid of the 19th century as a by-product of reactions under high temperatures. Yet this compound was not known to the world until the 1930s. Boron carbide is produced in a heat-resistance furnace. Only 15 percent of raw material can be converted into B4C in this process. Thereafter, the valuable boron carbide has become an important material for bulletproof armors, nuclear control rods, abrasives, etc.

Key Properties of Boron Carbide

This hard material is mainly characterized by:

* High Hardness: The Mohs hardness of boron carbide is between 9 and 10. Such stiffness and strength help boron carbide get the nickname “black diamond”.
* Low Density: It has a low density of about 2.52 g/{cm}^3 in the solidified form. Such lower density makes boron carbide a lighter choice for armor making.
* Chemical Inertness: Boron carbide rarely reacts with other chemicals. Such chemical stability leads to plenty of applications for this substance.
* Nuclear Ability: Boron carbide has a high cross-section to capture neutrons. So the boron carbide substance could serve as a neutron absorber and neutron detector in nuclear reactors.

Major Applications of Boron Carbide

The industrial uses of boron carbide include:

B4C as Protective Armors

Boron carbide is used to make protective tools to resist the impact of sharp objects like bullets, shrapnel, and missiles. It is usually combined with other composites during processing. Because of its high toughness, B4C armor is difficult for the bullet to penetrate. B4C material could absorb the force of the bullet and then dissipate such energy. The surface would shatter into small and hard particles later. Using boron carbide materials, soldiers, tanks, and airplanes could avoid serious injuries from bullets.

ACM’s Boron Carbide Bulletproof Plate provides strong protection for humans, motors, aircraft, etc. B4C bulletproof material has been widely used. It is quite easy to find B4C bulletproof glass, bulletproof vests, and bulletproof armor for military use. Boron carbide ceramic was applied to famous tanks like the current German Panther-Ⅱ, the British Challenger series, and the former Soviet Union’s T-72. It also appeals to airborne engineers since they could benefit from its low density and high hardness. Many more anti-ballistic products are using B4C ceramics thereafter.

B4C in Nuclear Reactions

Boron carbide is an extensively used control material in nuclear power plants for its neutron-absorbing ability, low price, and abundant source. It has a high absorption cross-section. Additionally, it produces no radionuclides, so the residual radioactivity level would be reduced. B4C ceramic is also an ideal shielding material in nuclear industries due to its heat resistance, no radioisotope production, and low cost. These products are available in powder form or solid form. ACM’s high-quality B4C products are the perfect choice for nuclear applications like control rods, shielding, and shut-down pellets.

Other B4C Applications

Boron carbide products serve as good abrasives for their outstanding stiffness. Thanks to such hardness, boron carbide could be used to polish and shape hard materials like metals. We could also find B4C material in cutting and grinding machines. It can be employed for cutting different alloys like Titanium alloy, aluminum alloy, and stainless steel. Due to such abrasion resistance, this tough material could be used as wear parts like blasting nozzles, wire-drawing dies, and thread guides.

Boron carbide is also well known for its excellent chemical properties like high corrosion resistance and heat resistance. So the products made from boron carbide are less likely to undergo corrosion. It is quite common to find high-security padlocks, tear-resistant coatings, and pipes and nozzles for very abrasive materials using boron carbide because of its inertness.

Conclusion

Boron carbide is an essential material with lightweight and great mechanical strength.

Additional Information

Boron carbide (chemical formula approximately B4C) is an extremely hard boron–carbon ceramic, a covalent material used in tank armor, bulletproof vests, engine sabotage powders, as well as numerous industrial applications. With a Vickers hardness of >30 GPa, it is one of the hardest known materials, behind cubic boron nitride and diamond.

Properties

Boron carbide is known as a robust material having extremely high hardness (about 9.5 up to 9.75 on Mohs hardness scale), high cross section for absorption of neutrons (i.e. good shielding properties against neutrons), stability to ionizing radiation and most chemicals. Its Vickers hardness (38 GPa), elastic modulus (460 GPa) and fracture toughness (3.5 MPa·m^{1/2}) approach the corresponding values for diamond (1150 GPa and 5.3 MPa·m^{1/2}).

As of 2015, boron carbide is the third hardest substance known, after diamond and cubic boron nitride, earning it the nickname "black diamond".

Semiconductor properties

Boron carbide is a semiconductor, with electronic properties dominated by hopping-type transport. The energy band gap depends on composition as well as the degree of order. The band gap is estimated at 2.09 eV, with multiple mid-bandgap states which complicate the photoluminescence spectrum. The material is typically p-type.

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#1 2024-11-05 17:01:13

Boron Carbide

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