Flexible miniaturized thin film thermocouples arrays for high temperature applications

Abstract

Thin film thermocouples (TFTCs) are critical for surface temperature measurements of hot components in high temperature environments. In this paper, miniaturized Pt/Pt-10%Rh thin film thermocouple arrays were fabricated on flexible Hastelloy substrates by magnetron sputtering. The morphology and microstructure of Al2O3/Y2O3 insulating films were investigated by a field-emission scanning electron microscope with an energy dispersive X-ray spectroscopy system. The thermoelectric performance of the TFTCs arrays was investigated by cyclic calibration and bending tests. During the whole calibration process, the average maximum temperature differences (ΔT′ ) of measuring points 2, 3, and 4 are 637 °C, 617 °C, and 574 °C, respectively, which differ from the maximum temperature difference (ΔT max ) of measuring point 1 by -13 °C, -34 °C, and -76 °C, respectively. The calibration results show that each single measuring point has good repeatability and stability during the five calibration processes, and the temperature difference between multiple measuring points is obvious, stable and reliable. The thermoelectric properties of the thin film thermocouple arrays barely change after 10,000 cyclic bending tests.