The Effects of Environment on the Interlaminar Shear Performance of an Oxide/Oxide Ceramic Matrix Composite at Elevated Temperature
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
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This research investigated the interlaminar shear performance of an oxideoxide ceramic matrix composite consisting of Nextel trademark 720 fibers in a high purity, porous alumina Al2O3 matrix. The interlaminar shear performance was observed in both tension and compression of double notched specimens DNS at 1200 C. Interlaminar shear creep behavior was examined in both laboratory air and in steam environment at 1200 C. In air, the creep stress was -6.5 MPa. In steam creep stresses included -4.0, -5.0, and -6.5 MPa. Primary and secondary creep regimes were observed in all air creep tests and the creep test in steam at -4.0 MPa. Tertiary creep was also observed in the creep tests in steam at -5.0 and -6.5 MPa. The specimens tested in creep at -6.5 MPa in air achieved run-out, defined as 100 hours at creep stress. The residual strength increased after 100 h of creep in air at 1200 C. In the presence of steam, creep performance deteriorated rapidly and run-out was achieved only at 50 the interlaminar shear strength. The fracture surfaces and the matrix of all samples were examined in order to determine the failure and environmental degradation mechanisms behind the reduced creep performance of the matrix in steam.
- Ceramics, Refractories and Glass
- Laminates and Composite Materials