Boron carbide is widely utilized in refractories, engineering ceramics, nuclear industry, aerospace, and other fields because of its high melting point, high hardness, low density, and awesome neutron absorption and chemical resistance.
1. Crystal shape of boron carbide
Complicated crystal structure of boron carbide with usual icosahedral boride. The stoichiometric method is B4C.
There are many isomers in B4C and boron carbide; the carbon content is from 8% to twenty%. The most solid boron carbide structure is b13c2, b13c3, B4C with rhombohedral shape, and different phases near b13c3. There are 12 icosahedral clusters inside the hexagonal structure of boron carbide, which might be related by using a covalent bond and feature a three atom chain on the diagonal of the hexagonal. The dodecahedral shape of the boron is placed on the apex of the rhombohedron.
Boron and carbon atoms can replace every other at the icosahedron and atomic chain, that’s the primary purpose why boron carbide has so many isomers. Due to its precise shape, boron carbide has many superphysical and mechanical properties.
2. characteristics of boron carbide
2.1 Hardness of boron carbide
The most critical overall performance of boron carbide lies in its fantastic hardness (Mohs nine.three, microhardness 55gpa-67gpa), that’s an excellent high-temperature wear-resistant material. Consequently, boron carbide, additionally called black diamond, is one of the three hardest materials recognized (the alternatives are the diamond and the cubic boron nitride), which is used in tank armor, bulletproof apparel and lots of business packages.
But, is boron carbide harder than a diamond?
The answer isn’t any. Boron carbide is no harder than diamond. As a hard black sleek crystal, boron carbide has a decreasing hardness than business diamond, but better hardness than silicon carbide. This is to mention, and boron carbide is the 5th hardest cloth recognized after boron nitride, diamond, fullerene compound, and diamond whole fiber tube.
2.2 Density of boron carbide
Boron carbide’s theoretical density is 2.52g/cm3,and relative density is (d204) 2.508 ~ 2.512.
It’s far the lightest ceramic fabric with minimum density and can be used in the aerospace field.
2.3 Chemical houses of boron carbide
Boron carbide has tremendous chemical properties. It does no longer react with acids, bases, and most inorganic compounds at room temperature. It most effectively erodes slowly inside the aggregate of hydrofluoric acid, sulfuric acid, and hydrofluoric acid, nitric acid. It is one of the compounds with the maximum solid chemical properties.
2.four different residences of boron carbide
in comparison with the natural factors B and CD, boron carbide has the blessings of low price, extremely good corrosion resistance, and thermal stability, and is widely used within the nuclear industry;
Boron carbide additionally has the blessings of high melting point, excessive elastic modulus, low enlargement coefficient, and use oxygen absorption ability;
Boron carbide is also a p-type semiconductor cloth, that can keep the semiconductor characteristics even at a totally high temperature.
Three. The application of boron carbide
The awesome hardness and great wear resistance of boron carbide make it an essential nozzle material. The boron carbide nozzle has the advantages of lengthy existence, incredibly low fee, time-saving, and high performance.
Neutron absorption and radiation safety substances
Detail B has a neutron absorption go-phase of as much as six hundred barns, which is the primary material for the discount element manipulates rod or radiation protection part of the nuclear reactor.
Composite armor cloth
It is able to be used as a mild bulletproof vest and armor cloth through its mild, top-notch tough, and high modulus. The bulletproof vest fabricated from boron carbide is extra than 50% lighter than that made from the equal metallic. Boron carbide is likewise a crucial bulletproof armor cloth for armored land automobiles, armed helicopters, and civil aviation airliners.
Semiconductor business additives and thermoelectric components
Boron carbide ceramics have semiconductor characteristics and better thermal conductivity, which can be used as high-temperature semiconductor additives, as well as gas distribution plate, focusing ring, microwave, or infrared window, DC plug, and many others. Inside the semiconductor enterprise. The mixture of B4C and C can be used as a high-temperature thermocouple detail, with the operating temperature up to 2300 ℃, and additionally as a radiation-resistant thermoelectric detail;
The excessive hardness of B4C makes it a top-notch put on-resistant fabric or antifriction fabric. Boron carbide is used rather than diamond abrasives within the sharpening, precision grinding, or grinding procedure of cemented carbide and engineering ceramics, which could drastically reduce the value of the grinding system.
The B4C coating can also be covered on the substrate to shape a shielding film and enhance the wear and tear resistance of the substrate. For example, making use of a B4C layer on the equipment floor of the gearbox can efficiently improve the wear and tear resistance of tools and improve the service existence of the equipment.
As an instance, in the subject of refractories, boron carbide is used as an antioxidant, mainly in low-carbon magnesia carbon bricks and castables.
Boron carbide performs a crucial position in aerospace, national defense, nuclear strength, and wear-resistant generation because of its superb performance. The instruction strategies encompass the carbothermal reduction approach, self-propagating thermal reduction approach, mechanochemical technique, direct synthesis technique, sol-gel approach, and so on.
At gift, the principle hassle hindering the software and popularization of boron carbide lies in the high value of guidance, and the high sintering temperature and vulnerable oxidation resistance of boron carbide itself.