Preparation and characterization of thermocouples on carbon fiber reinforced SiC ceramic matrix composites

Utilizing flame spraying technology, an Al 2 O 3 insulating layer was fabricated on a carbon fiber reinforced SiC ceramic matrix composite substrate. A Pt-PtRh 10 thermocouple was then constructed on the insulating layer through screen printing technology. The longitudinal resistance calibration results indicate that the insulating layer can support thermocouple operation at temperatures up to 1000 °C. High-temperature static calibration shows that the screen-printed thermocouple operates effectively at temperatures as high as 1042 °C for over 69 h, with an upper temperature limit of 1161 °C and potential for further enhancement. The average Seebeck coefficient stabilizes around 8.53 μV/°C, while drift rates gradually approach 0, stabilizing at 0.59 °C/h with increased cycles. These findings suggest that the screen-printed thermocouple offers extended lifetimes, excellent thermoelectric properties, significant stability, and outstanding reliability. This research provides valuable insights into sensor preparation on ceramic matrix composites.