CREEP AND ENVIRONMENTAL DURABILITY OF ENVIRONMENTAL BARRIER COATINGS AND CERAMIC MATRIX COMPOSITES UNDER IMPOSED THERMAL GRADIENT CONDITIONS

摘要

Interest in silicon carbide (SiC) fiber-reinforced silicon carbide ceramic matrix composites (CMCs) and environmental barrier coating (EBC) systems for use in high temperature structural applications has prompted the need for characterization of material strength and creep performance in complex aerospace turbine engine environments. Stress-rupture tests were performed on SiC/SiC composite systems with varying coating schemes to demonstrate material behavior under isothermal conditions. Additional testing was conducted under thermal stress gradients to determine the effect on creep resistance and material durability. In order to understand the associated damage mechanisms, emphasis was placed on experimental techniques as well as implementation of non-destructive evaluation (NDE), including electrical resistivity monitoring. The influence of environmental and loading conditions on life-limiting material properties is discussed.