Title

Integrated ceramic temperature sensors for harsh environments

Document Type

Conference Proceeding

Date of Original Version

12-1-2004

Abstract

The increase in turbine operating temperatures for both power generation and propulsion has lead to designs that incorporate complex cooling systems and thermal barrier coatings. Embedded wire thermocouples and strain sensors are frequently used for critical measurements in the gas turbine engine environment but as the blades get thinner, serious structural and aerodynamic problems can be encountered. Ceramic thin film thermocouples and RTD's based on reactively sputtered indium-tin-oxide (ITO) are being developed to measure the surface temperature of engine components that operate at temperatures in excess of 1500 °C. To enhance the charge carrier concentration difference in the ceramic thermocouples, for example, ITO elements were prepared by r.f. sputtering in oxygen rich and nitrogen rich plasmas. Thermoelectric powers on the order of 6μV/°C over the temperature range 25-1250°C were observed for ceramic thermocouples prepared in this manner and the thermoelectric response was nearly linear over this temperature range. Ceramic RTD's based on ITO were also prepared in a nitrogen rich plasma and thermally cycled in various oxygen partial pressures. The results indicated that the temperature coefficient of resistance (TCR) varied only slightly with oxygen partial pressure. TCR's ranged from 1320ppm/°C for sensors tested in 0.1 atm oxygen to 1804ppm/°C for sensors tested in 1 atm oxygen at temperatures above 750°C. Based on these results, a multifunctional sensor array has been envisioned whereby a ceramic RTD and strain sensor can be combined with a ceramic thermocouple on a common substrate, such that only two separate depositions would be required. The electrical response of these ceramic temperature sensors prepared under different plasma conditions is presented and potential applications of these ceramic sensor arrays in harsh environments will be discussed. ©2004 IEEE.

Publication Title

Proceedings of IEEE Sensors

Volume

3

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