Hexagonal boron nitride's structure and performance

What is hexagonal boron nitride?

Hexagonal boron nitride (H - BN), is a kind of white powder material, its crystal structure and graphite are very similar, and both the physical and chemical properties are similar, so the hexagonal boron nitride is also referred to as "white graphite", in the heat conduction, lubrication, hydrogen storage, battery diaphragm material, high temperature oxidation resistance coating, catalysis, etc all have important applications.  

Hexagonal boron nitride is a new kind of composite material, which not only has the advantages of low density, high melting point, low hardness, good thermal vibration resistance and machinability, but also has excellent properties such as high temperature resistance, low thermal expansion coefficient, high thermal conductivity, low dielectric constant and reliable electrical insulation.

Structure of hexagonal boron nitride  

From the molecular structure diagram, hexagonal boron nitrite belongs to hexagonal crystal system, which has the same hexagonal crystal structure as graphene. It is stacked by multiple layers, and b-N-B is linked by Van der Waals force between different layers. Its lattice constants a=0.2506±0.0002nm, C =0.667±0.0004nm.  Rho = 2.25 g/cm3 density.  

CBN is very stable in air with a wide band gap (5.1eV) and high hardness (Mohs hardness 2). It can withstand high temperatures at 2270℃ and only sublimate at about 3270℃.  At the same time, hexagonal boron nitride has the advantages of good insulation, thermal conductivity and chemical stability, low thermal expansion/shrinkage ratio, and does not react with weak acid and strong base at room temperature.