INVITED TALK: Thin Film Strain Gages for High Performance Applications

A key enabling technology to support advanced engine component development is strain and temperature measurement. Many issues arise when attempting to instrument ceramic matrix composites or CMC’s, considering they will be exposed to supersonic velocities, and gas temperatures approaching 1500°C. Thin film sensors are ideally suited for instrumenting CMC components, since they are deposited directly onto the surface of the CMC and become an integral part of the surface. Thin film sensors do not require adhesives and can survive the extremely large “g” forces. However, critical to their performance is the formation of a stable dielectric coating to electrically isolate the sensors from the CMC substrate. The merits of using metallic and ceramic thin film sensors for CMC’s will be reviewed and the most promising approaches for electrical isolation, temperature and strain measurement will be presented.