Effects of Temperature and Environment on the Mechanical Properties of Tyranno-Hex™ Composites
SourceTyranno-Hex™ is a newly-developed ceramic matrix composite (CMC) containing a high volume fraction (typically 90%) of fibers. The as-processed material exhibits strong bonding at the fiber-matrix interface; hence the composite behaves as a linear-elastic, brittle material at room temperature. However, at high temperatures (∼1200° C), a composite “toughening” mechanism develops and a large non linear region is apparent on tensile stress-strain curves. This change in behavior is related primarily to the relaxation of the interfacial bonding following the crystallization of the silica matrix into cristobalite. The measured mechanical behavior is discussed based on the microstructural assessment using transmission electron microscopy (TEM). Preliminary studies on coating techniques (sol-gel and powder metallurgy derived) for oxidation protection of the composite are also presented.