Metallic and Ceramic Thin Film Thermocouples

Abstract

Operating temperatures in the hot sections of modern gas turbine engines reach as high as 1500°C, making in situ monitoring of the severe temperature gradients on the surface of components rather difficult. Therefore, there is a need to develop thermocouples which can stably measure temperature in these harsh environments. Refractory metal and ceramic thin film thermocouples are well suited for this task since they have chemical and electrical stability at high temperatures in oxidizing atmospheres, they are compatible with thermal barrier coatings employed on engine components, have higher sensitivity than conventional wire thermocouples, and they are non-invasive to the engine environment. In this masters thesis, thin film combinatorial chemistry for materials discovery and characterization was the primary tool used to optimize thermo-element materials for thin film thermocouples. The resulting sensors based on ceramics, such as indium oxide and indium tin oxide, as well as others based on refractory metals, such as platinum and palladium, exhibited remarkable stability for many cycles at temperatures above 1000°C.