Improved nicr-nisi thin-film thermocouple manufacturing process enables accurate temperature measurement of UAV engines

Abstract

UAV engine turbine blade temperature measurement is an important basis for its working condition monitoring and health management, and high-temperature thin film thermocouple is considered to be an effective method to solve the problem of its temperature measurement in extreme environment. In this paper, the K-type NiCr-NiSi thin film thermocouple is taken as the research object, and the NiCr-NiSi thin film thermocouple is prepared on Ni-based superalloy substrate using electron beam evaporation and magnetron sputtering, and the improved thin film thermocouple consists of the Ni-based superalloy substrate, the NiCrAlY transition layer, the Al₂O₃  thermal oxide layer, alumina insulating layer, NiCr-NiSi thin-film thermocouple layer, and alumina protective layer. The results of calibration and compositional tests of the thin film thermocouple samples show that the improved NiCr-NiSi thin film thermocouple has a good linearity of Seebeck coefficient of 40.5 μV/K in 50~650 ℃, which is slightly lower than that of the standard thermocouple of type K with Seebeck coefficient of 41.0 μV/K. The dynamic performance of the temperature sensors has been investigated and tested both theoretically and experimentally, and the theoretical and experimental performance of the thermocouple has been investigated and tested. The dynamic performance of the temperature sensor was investigated and tested from both theoretical and experimental points of view. The theoretically calculated time constant was 38.5 μs, and the experimentally tested time constant was 85.05 us, with the response time in the same order of magnitude. The temperature measurement performance of the temperature sensor tested in a constant temperature field can meet the temperature testing requirements in the environment of up to 650°C, and can be reliably applied to the accurate temperature measurement of UAV engines.