Effects of adding 5–20 mol% ZrC plus 5 mol% Cu as a sintering aid on microstructure and mechanical properties of the TaC ceramics

TaC ceramics were prepared by hot pressing at 1900   °C for 30   min under 30   MPa mechanical pressure. Effects of the addition of 20   mol% ZrC or 5–20   mol% ZrC plus 5   mol% Cu as sintering aids on densification , phase composition, microstructure and mechanical properties of the consolidated materials were investigated. The results showed the pure TaC had a relative density of 86%of the theoretical value. Densities >97% theoretical were reached in the materials when the sintering aids were used. ZrC and TaC reacted to form solid solutions . The grain average size decreased from 18   µm in the pure TaC to 6   µm at 20   mol% addition. Addition of 5   mol% Cu further refined the microstructures. The 20   mol% ZrC+5   mol% Cu and the 10   mol% ZrC+5   mol% Cu composition had good flexural strength of 608   MPa and fracture toughness of 5.4   MPa   m 1/2 , respectively.