Structural Characteristics of Silicon Carbide and Boron Nitride

Silicon carbide and boron nitride both have good resistance to high temperatures and corrosion, etc. Do you want to know the difference? Please read on!

Silicon carbide (SiC) and boron nitride (BN) are two of the most important ceramic materials due to their outstanding properties. SiC and BN possess unique structural features that enable them to have high strength, extreme hardness, good thermal and chemical stability, and electrical conductivity. In this article, we will discuss the structure and properties of SiC and BN.

Silicon carbide has a crystal structure consisting of a hexagonal lattice of alternating layers of silicon and carbon atoms. The Si-C bond length is 188 pm, and the crystal symmetry is 6H polytype. SiC has a high melting point (approximately 2700°C), and it is considered as one of the most robust and enduring ceramics. The hexagonal structure of SiC results in anisotropic mechanical properties, meaning that it can withstand bending and compression forces in a different way depending on the direction of the force.

Boron nitride has two main crystal structures, hexagonal (h-BN) and cubic (c-BN). In h-BN, the boron and nitrogen atoms form an interconnected hexagonal network, whereas in c-BN the B-N bonds form a cubic structure. The BN bond length is 144 pm, and both h-BN and c-BN have high thermal stability, making them suitable for high-temperature applications. The layered structure of h-BN gives it similar properties to graphite, such as thermal and electrical conductivity in the basal plane. However, unlike graphite, h-BN is resistant to oxidation and can withstand higher temperatures.

Last but not the least, both SiC and BN possess unique structural features that enable them to have high strength, extreme hardness, good thermal and chemical stability, and electrical conductivity. These properties make them suitable for a wide range of applications, such as cutting tools, bulletproof vests, high-temperature electronics, and composites.