Effect of high temperature thermal exposure on properties of Al2O3/Al2O3 ceramic matrix composites

Abstract

The effect of thermal exposure at 1000 ℃ to 1200 ℃ on the properties of porous matrix Al2O3/Al2O3 ceramic matrix composites was studied. The results show that the thermal exposure at 1000 ℃ for 100 h has no effect on the tensile strength of the composites. After 100 h at 1100 ℃, the tensile strength of the composites decreases slightly, and after 100 h at 1200 ℃, the tensile strength of the composites decreases obviously. The effects of different thermal exposure durations at 1200 ℃ on the properties of Al2O3/Al2O3 composites, alumina fibers and alumina matrix are further studied, and the micro morphologies of the samples are characterized by optical microscopy and SEM. The results show that the thermal exposure at 1200 ℃ for 100 h has little effect on the performance of alumina fiber, but has a great effect on the alumina matrix. After the thermal exposure at 1200 ℃ for only 10 h, the porosity of alumina matrix is significantly reduced and the density is significantly increased. It can be seen from the SEM morphology of the matrix fracture that with the increase of thermal exposure time at 1200 ℃, the alumina grain size of the matrix gradually increases and the matrix is further sintered. Correspondingly， it can be seen from the fracture morphology of the Al2O3/Al2O3 composite that the length and number of fibers pulled out also decrease significantly. The degradation of the properties of the composites after high temperature thermal exposure is mainly due to the further sintering of alumina matrix, and the densification of porous matrix reduces the toughening effect of the composites.

Keywords

• thermal exposure
• alumina
• ceramic matrix composite
• tensile strength