Microstructure and Mechanical Properties of a Three‐Dimensional Oxide/Oxide Composite after Long‐Term Thermal Exposure

Herein, a three‐dimensional (3D) oxide fiber reinforced oxide matrix (oxide/oxide) composite is fabricated via slurry infiltration and sintering process. Subsequently, the effects of thermal aging on the microstructure and mechanical properties of the 3D oxide/oxide composite at 900 and 1100 °C are investigated. Experimental results indicate that the thermal aging affects the matrix microstructures and fiber/matrix interface. The elastic modulus of the matrix and interfacial shear strength increases with aging temperature and time. Aging treatment at 900 °C for 100 and 300 h results in a moderate decrease in the flexural strength and fracture toughness but improves the delamination resistance, whereas that at 1100 °C for 100 h lead to a significant decrease in the flexural strength and fracture toughness. The changes in mechanical properties might be attributed to matrix densification and enhanced interfacial bonding.