Ultrahigh-Temperature Ceramic Based on ZrB.sub.2-SiC: Preparation and Main Properties

Hot pressing of commercially available powders is used to prepare dense ceramic based on ZrB.sub.2 -SiC with different additives (Si.sub.3N.sub.4, TiSi.sub.2, ZrSi.sub.2, MoSi.sub.2). The main physicomechanical properties are measured in macro-specimens: ultimate strength in static three-point bending at room temperature 400 - 600 MPa, Vickers microhardness up to 15 GPa, and critical stress intensity factor up to 5.9 MPa·m.sup.1/2. Average LTEC, thermal diffusivity, thermal conductivity, and oxidation resistance over a wide temperature range are determined. Altogether the ceramic properties obtained are at the level of published indices.