3M Technical Ceramics
Zweigniederlassung der 3M Deutschland GmbH

Also known as black diamond

Chemical properties

Formula B₄C
Molecular weight 55.25 g/mole
Crystalline structure rhombohedric

Chemically inert (completely resistant to hydrogen fluoride and hot nitric acid)

Physical properties

Specification Weight 2.51 g/cm³
Extreme hardness 9.6 mohs
  • High resistance to wear at low working temperatures
  • High rigidity and very high E-modulus
  • Electrically conducting

Thermal properties

Melting point 2,350 °C

Good thermal conductivity

Manufacture and form

Boron carbide is manufactured from the raw materials boron oxide and carbon in an arc furnace at temperatures above 2,400 °C. Concurrently, the following reaction takes place:

2 B₂O₃ + 7 C → B₄C + 6 CO

The resultant shiny black crystals are separated from unreacted material, ground and classified in further preparation steps. Depending on its further use, the material is ground until in the sub-micron range.

Boron carbide can be used as a powder with various grain sizes or as a ceramic component. To manufacture ceramic components with high relative density, fine boron carbide powder with sinter additives is moved, processed with conventional ceramic-shaping methods and sintered or hot press-molded at temperatures above 2,000 °C in an inert gas atmosphere.

Typical use for boron carbide powder and grains are:

Typical uses for boron carbide components are: