A COMPARISON OF THE INTERPHASE DEVELOPMENT AND MECHANICAL-PROPERTIES OF NICALON AND TYRANNO SIC FIBER-REINFORCED ZRTIO4 MATRIX COMPOSITES

The differences in interphase development and mechanical properties between Nicalon and Tyranno fiber-reinforced ZrTiO4 matrix composites were assessed. The composites were reinforced with either uncoated or BN-coated fibers. The microstructure and interphase development were analyzed using scanning electron microscopy, transmission electron microscopy, and analytical electron microscopy. Mechanical behavior was characterized by strength and toughness measurements. Tyranno composites developed thinner interphases due to the differences in the structure and chemistry of the starting fiber resulting from the addition of Ti to the starting polymer precursor. BN-coated fiber composites developed a thicker carbon interphase layer due to incorporation of O into the as-received BN coating. Tyranno composites were weakened by fiber clustering and were not as tough as Nicalon composites due to a lack of thermal debonding.