Mechanical behaviors of hot-pressed 4TaC–1ZrC ceramics with and without Y2O3 and La2O3 additives

Abstract

4TaC–1ZrC ceramics with and without Y2O3 and La2O3 additives were prepared via hot-pressing at the temperatures ranging from 1650 °C to 1950 °C. Approximately 98% relative densities were obtained at or above 1900 °C for 4TaC–1ZrC ceramics with and without Y2O3 additive. Exceeding 99% relative density was obtained at 1700 °C for 4TaC–1ZrC ceramic with La2O3 additive. The elastic properties, electrical conductivity, hardness, fracture toughness and flexural strength of the highly-dense ceramics were evaluated. The results show that the elastic properties and hardness were insensitive to the sintering additives, but the fracture toughness, electrical conductivity and strength. The additions of Y2O3 or La2O3 significantly improved the room temperature strength of 4TaC–1ZrC ceramics, however, the strengthening effect substantially degraded at or above 1000 °C. The strengthening effect of La2O3 on 4TaC–1ZrC ceramic was the same as Y2O3 at room temperature, but was better than that of Y2O3 at elevated temperatures.