Hot gas stability of various ceramic matrix composites

This chapter examines the hot gas stability of oxide and non-oxide CMC, fabricated in different institutions of the CCeV in the burner rig of Fraunhofer IKTS Dresden. The tests were performed at 1250 °C and 1400 °C, a gas speed of 100 m/s and a water vapor pressure between 0.2 and 0.25 bar. The chapter also examines microstructure of surface and bulk material after hot gas test in comparison to the as fabricated materials. Various oxide materials were fabricated with hot gas resistant matrix materials, which exhibited superior hot gas stability. Information about the influence of the hot gas test on the mechanical behavior was obtained by comparison of the failure behavior in 3-point bending strength tests on samples prior and after the hot gas test. Embrittlement of the oxide CMC caused by grain coarsening of the ceramic fibers and matrix was observed with increasing test temperature.