Temperature‐Independent Conductive Ceramic for High‐Temperature Strain‐Sensing Applications
Chao Wu, Yingping He, Lanlan Li, Guochun Chen, Yanzhang Fu, Yingjun Zeng, Lida Xu, Fan Lin, Xiaochuan Pan, Qinnan Chen, Yang Zhao, Daoheng Sun, Zhenyin Hai
Abstract
Temperature‐independent properties are critical for high‐temperature thin‐film strain gauges (TFSGs). In this study, by controlling the electron scattering and tunneling effects in the TiB 2 /SiCN composites, the environmental interference of temperature fluctuations is successfully eliminated, and a temperature‐independent TFSG is fabricated. The effects of pyrolysis temperature and TiB 2 content on the microstructural evolution and electrical properties of the ceramic films are studied. The temperature insensitivity is mainly attributed to the balance between the intrasheet resistance with a positive temperature coefficient of resistance (TCR) and the intersheet resistance with a negative TCR. This composite shows nearly constant resistance values over an ultrawide temperature range of 300–700 °C, with less than 0.05% deviation of the normalized resistance and TCR values as low as 1.6 ppm °C −1 . In addition, the TiB 2 /SiCN films exhibited stable piezoresistive responses, with a gauge factor of 4.28, and the temperature‐independent strain response in the high‐temperature range is verified.