Enhanced high-temperature stability of indium tin oxide-Indium oxide thermocouples by two-step annealing

The complex internal structure of the aero-engine and the high-temperature, high-pressure, and high-speed airflow make it difficult to measure the internal temperature. Indium tin oxide (ITO) and In2O3 films have been studied for their application in high-temperature thermocouples and strain gauges. Due to their large Seebeck coefficient and high-temperature stability, ceramic thin-film thermocouples are expected to be used at high-temperature measure. In this paper, ITO-In2O3 thermocouples were fabricated by magnetron sputtering. Besides, the electrical properties of the air-annealed and two-step nitrogen-annealed thermocouples were compared, including the repeatability of thermoelectric response after multiple thermal cycles and the drift rate during the high-temperature duration. The microstructure and electrical conductivity of both the as-deposited and post-annealed ceramic thin films were tested respectively. The result shows that the resitivity and See-beck coefficient of the thin films annealed in nitrogen is reduced, but the stability at high temperature is greatly improved.

Automated summary

This paper studies the application of indium tin oxide (ITO) and indium oxide (In2O3) films in high-temperature thermocouples and strain gauges. ITO-In2O3 thermocouples were fabricated by magnetron sputtering. The electrical properties of air-annealed and two-step nitrogen-annealed thermocouples were compared.