POLYCRYSTALLINE BORON CARBIDE SHAPED PARTICLES

A method of producing dense shaped articles of pure boron carbide that optionally contain 0.1 to 8% by weight of free carbon in the form of graphite is disclosed involving the steps of homogeneously mixing boron carbide in submicron powder form with small quantities of a carbon containing additive, forming the powder mixture into a shaped green body and then sintering the body in a controlled atmosphere and in the absence of external pressure at a temperature of about 2100 DEG -2200 DEG C. The shaped articles thus obtained are polycrystalline and, insofar as they correspond to the stoichiometric composition B4C, single-phase; they have an average grain size of not more than 10 mu m, a density of at least 90% of the theoretical density of boron carbide and a flexural strength of at least 300 N/mm2. The fracture mode of the sintered articles is completely transcrystalline.