[en] A method of sintering silicon carbide powders containing boron or boron - containing compounds as densification aids to produce a high-density silicon carbide ceramic material is described. It has been found that higher densification can be obtained by sintering the powders in an atmosphere containing boron. Boron may be introduced in the form of a gas, e.g. boron trichloride, mixed with the inert gas used, i.e. nitrogen, argon or helium, or boron compounds, e.g. boron carbide, may be applied to the interior of the sintering chamber as solutions or slurries. Alternatively a boron compound, per se, in the sintering chamber, or furnace components containing a significant amount of boron may be used. (U.K.)