Steven G. Steel

Monotonic and Fatigue Loading Behavior of an Oxide / Oxide Ceramic Matrix Composite Steven G. Steel

The demanding environment in aircraft turbine engines has driven the development of many innovative high temperature materials. This thesis examines one of the latest of these materials, an oxide/oxide ceramic matrix composite (CMC), N720/A. This CMC consists of a porous alumina matrix reinforced by Nextel 720 fibers in a balanced 8 harness satin weave. To characterize this material, monotonic tensile and cyclic fatigue tests were performed at room temperature and at 1200??. The effects of moisture on fatigue behavior were also investigated at 1200??. Modulus, maximum and minimum strain and stress strain hysteresis were monitored during the cycling to characterize fatigue damage mechanisms. Retained strength of all specimens that survived I Os cycles was also characterized. Microscopy and fractography were used to examine microstructure, damage mechanisms, and fracture surfaces. N720/A was found to have good room temperature and high temperature properties.