High temperature thermocouples for SiC-CMC based gas turbine engine components

K. Rivera, O.J. Gregory
University of Rhode Island,
United States

Keywords: thermoelectricity, thin films, barrier coatings, high temperature

Summary:

SiC-based ceramic matrix composites (CMCs) are replacing Ni based superalloys as the material of choice for advanced gas turbine engine components, due to their superior thermomechanical properties. At the present time, instrumentation to measure surface temperature of SiC-based CMC engine components does not exist. Thus, the development of sensors to accurately measure surface temperature is of considerable interest to the gas turbine engine industry. To address this need, thermocouples in which indium tin oxide is one thermoelement and the SiC-CMC itself is the other thermoelement, have been developed as a viable solution for surface temperature measurement. These thermocouples have a thermoelectric power of 270uV/°K, which is an order of magnitude larger than type-K thermocouples. When suitable diffusion barrier coatings were applied, these thermocouples were able to survive temperatures > 1100°C with drift rates