K-type Thin Film Thermocouples Deposited on Ni-based Superalloy Substrates

摘要

NiCr-NiSi K-type thin film thermocouples with multi-layer structure were fabricated on Ni-based superalloy substrates (95 mm×5 mm×2 mm). The multi-layer structure contains NiCrAlY buffer layer (2 urn)/ thermally grown AI2O_3 bond coating (200 nm)/ A12O_3 insulating layer (8 um)/ NiCr-NiSi thin film thermocouples (1 um)/ A1_2O_3 protecting layer (500 nm). The samples were statically calibrated in a tube furnace in the temperature range from 170 °C to 610 °C. The results show that the resistance of AI2O_3 insulating layer is about 14.6 kQ. at 800 °C and exceeds 100 M£2 at room temperature. The Seebeck coefficient a of the samples is about 34 uV/°C, and the sensitivity coefficient K is greater than 0.8 in the temperature range from 170 °C to 610 °C. The maximal sensitivity coefficient is about 0.97 at 265 °C.