DENSIFICATION OF TANTALUM CARBIDE CERAMICS WITH 5 MOL% Al, Cu, Ag AND Au

Tantalum carbide (TaC) has attracted extensive research interest as an ultrahigh temperature material suitable for aerospace applications as it has one of the highest melting points, up to 3997 C. However, pure TaC ceramics are extremely hard to densify. The effects of adding 5 mol% aluminium, copper, silver or gold on the densification, microstructures, mechanical properties and oxidation resistance at low air pressure of TaC ceramics were investigated. Full density and relatively high flexural strength (up to 738 MPa) were seen in the case of the Au addition after spark plasma sintering at 1700 C for 5 min under 30 MPa pressure. Due to wetting of the TaC grains by a thin metallic film, the consolidated materials showed enhanced oxidation resistance under low air pressure.