Effects of steam environment on creep behavior of Nextel™720/alumina ceramic composite at elevated temperature

Cyclic creep and recovery behavior of Nextel™720/alumina ceramic composite at 1200°C

“…Additional sintering of the matrix during the aging treatments was considered to be associated predominantly with Al 2 O 3 . Results or previous studies by Ruggles-Wrenn et al [28,32,33] suggest that the sintering of the matrix is accelerated in the presence of steam.…”

“…A previous study [28] revealed that for N720/A composite tested at 1200 • C in air and in steam, the fracture surface appearance could be correlated with the failure time, with a predominantly planar fracture surface corresponding to a short lifetime and fibrous fracture indicating longer lifetime. Examination of the fracture surfaces in Figs.…”

Creep of Hi-Nicalon S Ceramic Fiber Tows at 800 deg C in Air and in Silicic Acid-Saturated Steam

“…The dependence of tensile strength on stress rate observed by Ruggles-Wrenn et al [178][179][180] for CMCs and the failure of fibers at lower stresses and temperatures than expected (delayed failure) noted by Forio, Gautier, and Lamon [120,121,125] for Hi-Nicalon T M S fiber tows are related and akin to that observed for the monolithic ceramics at elevated temperatures [181][182][183]. For monolithic ceramics, these phenomena have been shown to proceed by environmentally assisted subcritical crack growth (or slow crack growth) [184].…”

“…For both oxide-and non-oxide-based CMCs and fiber tows, it has been shown that the monotonic tensile behavior and tensile properties are influenced by loading rate [4,120,121,125,[175][176][177][178][179][180]. This is of concern in structural applications where loading rates vary widely, such as the aerospace applications for which oxide and non-oxide CMCs are being developed.…”

Durability of Oxide/Oxide Ceramic Matrix Composites in Gas Turbine Combustors

“…The CMC matrix is alumina (designated A), infiltrated by the sol-gel process, and consolidated by firing. Table 1 summarizes materials' property data for N720 fiber and N720/A CMC plates, fabricated by ATK COI Ceramics (COIC) [17,[19][20][21][22].…”