Advanced ceramic components with embedded sapphire optical fiber sensors for high temperature applications

Highlights: • We developed an additive manufacturing process to enable embedment of sensors in ceramic components during fabrication. • Sapphire optical fiber sensors for high temperature applications were embedded in additively manufactured alumina parts. • Scanning electron microscopy showed good bonding between sensors and parts, without any flaws/defects at their interfaces. • Sensors were able to endure the freeform extrusion fabrication process and also the post-processing. • Mechanical properties of parts with embedded sensors having diameters smaller than 250 microns were not deteriorated. This paper describes an extrusion-based additive manufacturing process that has been developed to enable embedment of sapphire optical fiber sensors in ceramic components during the part fabrication. In this process, an aqueous paste of ceramic particles is extruded through a moving nozzle to build the part layer-by-layer. In the case of sensor embedment, the fabrication process is halted after a certain number of layers have been deposited; the sensors are placed in their predetermined locations, and the remaining layers are deposited until the part fabrication is completed. Because the sensors are embedded during the fabrication process, they are fully integrated with the part and the problems of traditional sensor embedment can be eliminated. Scanning electron microscopy was used to observe the embedded sensors and to detect any possible flaws in the part or embedded sensor. Attenuation of the sensors was measured in near-infrared region (1500–1600 nm wavelength). Standard test methods were employed to examine the effect of embedded fibers on the strength and hardness of the parts. The results indicated that the sapphire fiber sensors with diameters smaller than 250 micrometers were able to endure the freeform extrusion fabrication process and the post-processing without compromising the part properties.