ZrB2-SiC Composites with Rare-Earth Oxide Additives

Abstract

The effect of different content (2, 5, and 10 wt.%) of two different types of rare earth (RE) oxides (Eu2O3 and Lu2O3) on the sintering, microstructure, room temperature mechanical properties, and ablation resistance of ZrB2-25vol.% SiC ceramics were investigated. The materials were prepared using non-reactive Field Assisted Sintering Technology (FAST) in the temperature range of 1950°C – 2050°C, with a pressure of 70 MPa and a dwell of 7 min. No significant effect of the addition of 2 and 5 wt.% RE2O3 on the microstructure and the room temperature mechanical properties (hardness, indentation fracture toughness, and flexural strength) were observed. On the other hand, the coarser microstructures led to the deterioration of flexural strength and the hardness of the composites sintered with 10 wt.% RE2O3. The ablation resistance of the materials (tested up to ~ 2670°C) gradually increased with the increasing amount of RE oxides. The material with 10 wt.% Lu2O3 showed the best ablation resistance among all of the investigated compositions, with more than two times a lower ablation rate than that of the reference ZrB2-25vol.%SiC.