Composite Coating-Based Heat Flux Sensor for In Situ Heat Flux Monitoring of Hot-End Components

The control of thermal energy during the operation of aeroengine turbine blades in extreme environments is crucial for the reliability of the associated equipment. Among the key parameters influencing thermal energy transfer, heat flux density plays a significant role. The development of heat flux sensors on the surface of turbine blades enables real-time measurement of these critical parameters. However, extreme conditions of high temperature and pressure present challenges, such as the tendency for surface coatings on turbine blades to peel off and for insulation properties to degrade. To address these issues, we propose a composite process for the in situ preparation of high-temperature heat flux sensors. The composite gradient coating, applied via plasma spraying, ensures the reliability of the coating and enhances its insulating properties, with the insulation resistance reaching 20 k<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Omega $ </tex-math></inline-formula> at a high temperature of 1100 °C. Additionally, curved, conformal high-temperature thin-film sensitive layer electrodes and thermal resistive layers are prepared in situ on the coating surface using physical vapor deposition (PVD). This method, characterized by nonintrusive flow and conformality, enables the measurement of heat flux up to 1.9 MW/m2, with a measurement error of less than ±2.5% FS. The proposed approach offers a feasible solution for the real-time monitoring of heat flux density parameters on blade surfaces in extreme environments.