b'error in thermal diffusivity betweenCVD, CVI and fiber regions was 36.8, measurements taken on the inner15.7, and 6.4 mm 2 /s, respectively and outer surfaces of the cladding(obtained by Hua). This demon-curvature. Idaho National Labora- strates that the TCM instrument torys advanced data analysis (devel- is sensitive on the length scale of oped by Pavlov) allows for a correc- the heterogeneous features of the tion due to the curved geometry andSiC-SiC composite.that the correction factors of curvedA heating stage on the TCM was samples are different dependingused to heat a SiC-SiC cladding / Sn / upon the heating and measurementMo cross-section from room temper-Figure 2. Cross-section area of SiC-SiCsurfaces. This information will beature to 180C to examine the effect cladding where local thermal diffusivityused to correct the LFA measure- on thermal diffusivity from the measurements were collected.ments that will be conducted onSn bonding layer. Figure 3 shows Composite features are labeled in red the SiC-SiC cladding/Sn/Mo layered system in future work. the thermal diffusivity at various temperatures (obtained by Adkins The TCM instrument measuresand Hua) across the SiC-SiC clad-thermal diffusivity at the surfaceding, the Sn layer and the Mo center of a sample on a meso-scale levelregion. It is noteworthy that the which can be 20-100 m in lengthvalues for diffusivity in the SiC-SiC to capture microstructural effect onregion are lower than the CVD the thermal transport of that area ofand CVI values reported at room a material. The SiC-SiC compositetemperature up to 125C where was cut across the tube and athey begin to increase. The scatter portion was mounted into epoxy,in the values at all locations within polished and coated with a thina specific temperature is likely due layer of gold for data collection withto a high surface roughness at the the TCM. Five area cross-sectionslocation of the TCM measurement of the SiC-SiC cladding tube werewhich can scatter the laser beams examined for thermal diffusivity.and introduce noise into the data. Each area was a combination ofAbove 180C the integrity of the chemical vapor deposit (CVD) andgold coating was compromised in chemical vapor infiltration (CVI)the vacuum chamber during testing SiC and SiC fiber features. Figure 2 istherefore scattering the lasers an optical micrograph of one of thebeyond the ability to measure diffu-cross-sections that was examinedsivity. The next step in this study with the different features labeled.will be to conduct measurements The average thermal diffusivity ofinside the heating stage under an 64 2023|AFC ACCOMPLISHMENTS'