TiB₂/SiCN Thin-Film Strain Gauges Fabricated by Direct Writing for High-Temperature Application

Abstract

The in situ strain/stress monitoring of hot components in harsh environments remains a challenging task. In this study, TiB ₂ /SiCN thin-film strain gauges were fabricated on nickel base alloy substrates via direct writing. The static and dynamic strain responses were investigated from 25 °C up to 800 °C. The results show that this thin-film strain gauge fabricated by ceramic-based materials exhibits excellent thermal stability and strain response. Without any anti-oxidative protective layer deposited, its operating temperature is as high as $700^{\circ }\text{C}$ , which is 200 °C higher than that of the high-temperature piezoresistive thin-film strain gauges that have been developed and comparable to thin-film strain gauges with protective layers. The gauge factor of theTiB ₂ /SiCN high-temperature thin-film strain gauge is 7.12, which is higher than that of most high-temperature thin-film strain gauges. In addition, the strain gauge exhibits excellent resistance stability with a mechanical hysteresis of $3~\mu \varepsilon $ and a resistance drift of 0.0008/h at room temperature. Therefore, TiB ₂ /SiCN thin-film strain gauges provide an effective approach for the measurement of in-situ static and dynamic strain of hot components in harsh environments.