Embedded Heat Flux Sensors with Direct Write Thermal Spray

Direct write thermal spray enables incorporation of sensors within plasma sprayed thermal barrier coatings for in-situ diagnostics and sensing, and ex-situ property characterization as well.  In this work, multiple heat flux sensors will be deposited onto an in-situ coating property (ICP) sensor, which provides evaluation of curvature and stress state of coating systems.  With thermocouples embedded into the coating at different in-plane and/or through-thickness locations, it is possible to extract heat flux through the coating and examine thermal gradients.  The in-plane sensor arrangement provides thermal response of lateral heat transfer, which occurs during thermal spraying process; while the through-thickness arrangement allows evaluation of thermal gradient in spraying direction, especially for the ex-situ aging studies. The as-sprayed coatings will be heat treated via a burner rig, and the output of heat flux sensors will be correlated to the thermal conductivity change due to graded annealing.  Moreover, modeling work will be developed to enable not only examination of the embedded sensor data but also allow an assessment of the dynamic evolution of the coating thermal performance during service.