Compressive Creep Behavior of NEXTEL(TradeMark) 720/Alumina Ceramic Matrix Composite at 1200 Degrees C in Air and in Steam Environment
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH DEPT OF AERONAUTICS AND ASTRONAUTICS
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The aerospace community continues to push the envelope in engineering aircraft that fly higher, faster, and safer while operating with a greater degree of efficiency. To meet these operational requirements innovative aerospace components must be designed to operate in aggressive environments. This research will investigate the ultimate compressive strength and the compressive creep behavior of NextelTM 720Alumina ceramic matrix composite at 1200 deg. C in air and 100 steam environments. The effects of creep loading history on the tensile and compressive material behavior will also be examined. The primary strengths of the N720A composite are its oxideoxide composition which inherently resists oxidation and a porous matrix which enables crack deflection producing enhanced matrix damage tolerance. Mechanical testing showed a significant decrease in the compressive performance of N720A when exposed to steam environment. Conversely, N720A specimens tested in compressive creep in air experienced an increase in compressive performance. SEM analysis showed that densification of the alpha-alumina matrix occurred in both test environments. In air densification sinters the matrix resulting in a strengthening effect. Whereas, in steam environment analysis shows the addition of hydrogen induces hydrothermal softening of the matrix resulting in a significant loss of the compressive performance of N720A.
- Physical Chemistry
- Ceramics, Refractories and Glass