Session: 05-01 Smart Sensors for SHM

Paper Number: 163432

163432 - Refractory Compact Heat Exchangers With Embedded Sensors Enabled by Hybrid Advanced Sintering and Additive Approach - Invited Speaker 

Structural health monitoring (SHM) of high-temperature refractory alloy compact heat exchangers (CHXs) is crucial for ensuring the reliability, safety, and efficiency of systems used in critical industries such as energy production, aerospace, and chemical processing. These CHXs operate under extreme conditions, where both thermal (over 1000°C), corrosion (molten salt environment), and mechanical stress exert significant load on material integrity and performance. Real-time SHM enabled by embedded sensors provides a proactive approach to sense the operational condition of the components. Additionally, these embedded sensors allow for the continuous assessment of thermal gradients, stress distributions, and potential failure point, thereby reducing the risk of unplanned downtime and supporting further design optimization of CHXs. However, embedding sensors in CHXs faces significant challenges due to the aspect ratio and limited space of the channels in CHXs. This study proposed the embedding of multimodal sensors in refractory CHXs via a hybrid approach consisting of electric field-assisted sintering (EFAS), material extrusion, and aerosol jet printing (AJP). The methodology started with the fabrication of sacrificial channel molds with material extrusion. After that, sensors were printed on sacrificial channel molds via AJP, after which the molds were embedded in refractory alloy powders and experienced sintering at high-temperatures and pressure using EFAS. After EFAS, the sacrificial channel molds were dissolved chemically, forming the CHX channels while the sensors were left behand and attached to the channel walls. Initial sensor development in this study includes the printing and testing of sensors from tungsten, gold, and platinum. These sensors were printed by AJP after the optimization of the sensor design, printing parameters, and sintering conditions. The printed sensors were tested in a furnace for temperature measurement. The results demonstrated that the sensors can successfully measure temperature up to 1000°C. However, tungsten sensor requires testing in oxygen-controlled environment to prevent oxidation of tungsten at temperature above 450°C. To further protect the sensor and provide electrical insulation when embedded in CHXs, a thin layer of ceramic coating was applied on the sensors which was observed to enhance the reliability of the sensors at high temperatures. After successful measuring of temperatures with the printed sensors, these sensors were embedded in refractory alloys using EFAS. The embedding was accomplished by encapsulating the sensors in powders being sintered. Direct bonding of printed sensors on CHX solid blocks was also explored via diffusion bonding technique. Sensing using the embedded sensors in refractory alloys was performed to demonstrate sensor functionality of these sensors. At last, both non-embedded and embedded sensors were examined using advanced microscopy to reveal the microstructural features of these sensors and their bonding with the refractory alloys.        

Presenting Author: Xinchang Zhang Idaho National Laboratory

Presenting Author Biography: Dr. Xinchang Zhang is a Materials Scientist within the Materials Science and Manufacturing Department at Idaho National Laboratory. His primary research areas are focused on the processing of advanced materials using advanced manufacturing techniques, process development using hybrid manufacturing, embedding of high-temperature sensors for structural health monitoring, and materials testing. He holds a Ph.D. in mechanical engineering from Missouri University of Science and Technology in 2019. His honors include Dean’s Ph.D. Scholar Award, Best Paper Award in 2018 International Solid Freeform Fabrication Symposium, NSF Travel Award, Outstanding Reviewer for the journal Additive Manufacturing, etc. He also serves as the reviewer for the leading journals in the area of advanced manufacturing and material science, including Additive Manufacturing, Materials Science and Engineering: A, Science and Technology of Welding and Joining, ASME-Journal of Manufacturing Science and Engineering, etc.