Difficult-to-sinter ceramics—boron carbide

Boron carbide (B4C) has extremely strong B-B and B-C covalent bonds and is one of the most difficult ceramics to sinter. However, due to its low density (2.52 g.cm-3), high melting point (2450oC), high hardness (the microhardness Hv value is about 30 GPa, second only to diamond and cubic boron nitride), high elastic modulus (448 GPa) and high neutron absorption cross-section (600 target), thus becoming an extremely important strategic resource.

The atomic bond combination of B-B and B-C constructs the crystal structure of B4C. The B4C crystal can be described by a rhombohedral lattice and belongs to the R-3m space group. The special crystal structure of B4C determines its thermal, electrical and mechanical properties. Knowing the crystal structure of B4C is of great significance for understanding the special properties of B4C that distinguish it from other ceramics.