In-situ Sensors Deposited by Laser Cladding

A new method for fabricating microsensors which can provide accurate real-time temperature monitoring of thermal barrier coatings on gas turbine engines was developed. A high temperature K-type thermocouple sensor for hostile environments was deposited using a coaxial laser cladding process with optimized process parameters giving minimal intrusive features to the substrate and afterwards embedded in typical ceramic layers. The dimensions of the cladded thermocouple were less than two hundred microns in thickness and width. The thermal and electrical response of the cladded thermocouple was tested before and after embedding over temperatures ranging from ambient up to approximately 500 ^oC in a furnace with flowing argon as protective gas. The results were compared to that of a commercial standard K-type thermocouple, which indicate that laser cladding is a promising technology for manufacturing microsensors for in-situ monitoring in harsh operation environments.