Notch-Sensitivity of a Woven Oxide/Oxide Ceramic Matrix Composite

摘要

Oxide/oxide ceramic matrix composites (CMC) are currently being demonstrated in high-temperature aerospace applications. An oxide/oxide CMC under consideration by the U.S. Air Force is Nextel720/AS, which consists of an alumina-silica matrix (AS) reinforced with a woven Nextel720 fiber mat. The fracture behavior of notched Nextel720/AS at room and expected service temperatures is discussed in this paper. Specimens with semi-circular and narrow double-edge notches were tested under monotonic loading in laboratory air at 23 to 1200℃, and under sustained (creep) loading at 1100℃. The results show that Nextel720/AS is notch-insensitive at low temperatures (≤ 1000℃) and ≈22% notch-sensitive at higher temperatures (≥ 1100℃) under tensile loading. At 1100℃, the notch-sensitivity increased significantly under sustained loading.