ELEVATED-TEMPERATURE FRACTURE CHARACTERIZATION OF ADVANCED FIBROUS CERAMIC THERMAL INSULATORS

The elevated-temperature mechanical behavior of two low-density fibrou s ceramic thermal insulators is discussed. Fracture toughness and R-cu rve behavior are obtained from chevron notched bend bar and short doub le cantilever beam specimens, respectively. The fracture behavior is r elated to the bulk microstructures, the properties of the fibers, and the various fiber-to-fiber bond chemistries. A strong behavioral chang e at elevated temperatures is linked to the glass-softening temperatur e of the multiphase structure characteristic of each material.