Infrared Pyrometric Technique for in-situ Temperature Measurements inside the Substrate in Atmospheric Plasma Spray Coating Processes

Thermal spray coating processes have become one of the most used technologies for obtaining low-cost components with advanced surface requirements for multiple industrial sectors, such as aeronautics, automotive, medical, and electronics. Atmospheric plasma spraying (APS) is the most flexible thermal spray technique to allow the processing of a wide range of metallic materials, metal oxides, and even ceramics, with excellent control of coating thickness and surface characteristics. An important factor to consider in the APS process is the generation of residual stresses and cracks in the coating layer, mainly due to the high-temperature gradients generated in the surroundings of the coating-substrate interface. Several contact and non-contact temperature monitoring techniques have been used during the APS coating process; however, these techniques can only measure the temperature on the substrate surface. This work proposes a novel non-contact, low-cost infrared pyrometric technique for in-situ temperature measurement at different substrate depths without interfering with the coating process.