Microstructure, mechanical properties and thermal stability of Al2O3/Al2O3 ceramic matrix composites obtained from submicron-sized powers

Improvement in thermal stability is especially important for the oxide/oxide composites, which are widely applied at high temperatures. Herein, the continuous alumina fiber reinforced alumina matrix (Al2O3/Al2O3) composites were fabricated at 1200–1400 °C using Al2O3 powders with a mean size of 0.6 μm. The Al2O3/Al2O3 composite fabricated at 1300 °C achieved a high flexural strength of 392.9 ± 20.1 MPa and a high interlaminar shear strength of 20.6 ± 1.0 MPa. After exposure at 1000 °C for 100 h and 1400 °C for 10 min, the 1300 °C fabricated Al2O3/Al2O3 composite showed no significant reduction in mechanical properties. A slight decrease in mechanical properties was observed after aging at 1200 °C for 100 h. The high strength retention after the heat treatment benefited from the coarse Al2O3 powders, which could not be easily sintered at high temperatures. This work can expand the selection of the Al2O3/Al2O3 composites for potential applications at service temperatures as high as 1400 °C for a short term.