High temperature compressive strength and creep behavior of SiTiCO fiber-bonded ceramics

Fiber bonded silicon carbide ceramic materials provide cost-advantage over traditional ceramic matrix composites and require fewer processing steps. Despite their interest in extreme environment thermostructural applications no data on long term mechanical reliability other than static fatigue is available for them. We studied the high temperature compressive strength and creep behavior of a fiber bonded SiC material obtained by hot-pressing of SiTiCO fibers. The deformation mechanism and onset of plasticity was evaluated and compared with other commercial SiC materials. Up to 1400 °C, plasticity is very limited and any macroscopic deformation proceeds by crack formation and damage propagation. A transient viscous creep stage is observed due to flow in the silica matrix and once steady state is established, a stress exponent n ∼ 4 and an activation energy Q ∼ 700 kJ mol−1 are found. These results are consistent with previous data on creep of polymer derived SiC fibers and polycrystals.