Embedment of sensors in ceramic structures

Demonstration of Embedded Sensors in Ceramic Structures

“…The low densities of the fused silica optical fibers make the fibers difficult to distinguish from voids in the XCT images. However, because previous material compatibility tests showed that the fibers survive the CVI process, as shown in Section 3.1 and previous work [4], the fibers are likely located in the regions indicated in Figure 8. Figure 8 shows that at least one of the two fibers was misaligned inside its sheath.…”

“…Because HCl is a product of MTS thermal decomposition, the sensors and sensor sheaths must be compatible with HCl and the H 2 carrier gas at temperatures of ~1,000°C. Previous work showed that Mo, Nb, and other refractory metals are promising sheath materials [4]. Amorphous SiO 2 optical fibers also survived the CVI process and were successfully embedded in SiC.…”

“…The 3D printing process, described briefly in the next section and in more detail in a previous work [3], involves binder jet printing complex geometries followed by densification with chemical vapor infiltration (CVI). This process provides a unique opportunity to directly embed sensors into the printed SiC ceramic components at strategic locations that would otherwise be inaccessible via traditional manufacturing approaches [4].…”

“…As mentioned in a previous work [4], the primary embedded sensors of interest for the TCR core include thermocouples, spatially distributed fiber-optic temperature sensors, and SPNDs. For the range of temperatures being considered for the TCR reactor (~350-550°C coolant temperatures), Type K and Type N thermocouples are well-suited.…”

“…The contents include results from materials compatibility tests to determine sensors and sheath materials that can survive CVI and initial trials for embedding functional sensors. The primary challenges for embedding sensors in SiC components include identifying suitable sensor and component geometries and materials and routing of the sensor leads during CVI [4]. The high temperatures and chemically aggressive environment to which the sensors are exposed during CVI greatly limit the candidate materials and sensors and require careful design to avoid breaking the sensors or damaging the sensor sheaths.…”