Polycrystalline shaped body of silicon carbide and method for its production

Polycrystalline shaped body of a density of at least 98% of the theoretical density of silicon carbide, consisting of at least 92 weight % of alpha -silicon carbide and/or beta -silicon carbide, which is present in the form of a homogeneous texture with grains of maximal 10 mu m, and is characterized by the fact that, besides a content of up to 3 weight % of boron, a share of about 0.5 to 5 weight % of a metal or rare earth element that acts reducing or mixtures thereof is present, and the body shows a transverse rupture strength (determined by the four-point method) of at least 500 N/mm2 up to 1,400 C and is essentially free of free carbon. A method for the production of shaped bodies through the pressureless sintering of the silicon carbide starting material, characterized by the fact that about 0.5 to 5% of metals or rare earth elements are added individually or as mixtures to the starting material, that the resulting starting material mixture is shaped, and the shaped body pressureless sintered at temperatures from 1,900 DEG to 2,200 DEG C. under vacuum or in a protective gas atmosphere.