Sustainable high emissivity of Si–Zr–C–O fiber felts despite oxide layer formation in oxidative environment

抄録

The effect of oxide layer formation on the emissivity of Si–Zr–C–O fibers was examined in this study. In order to form a uniform oxide layer on each fiber surface, the Si–Zr–C–O fiber felt was exposed to air at a high temperature. The oxide layer consisted of SiO₂ (cristobalite) and dispersed 10–25 nm ZrO₂ particles. Whereas, the fiber core itself exhibited no microstructural changes crystallographically or morphologically despite the exposure. The total emissivity of the exposed fiber felt calculated at 1000°C was 87.6 ± 4.1% and exhibited a similar value to the initial total emissivity (89.2 ± 4.2%). These results indicated that the emissivity of the Si–Zr–C–O fiber felt was unchanged irrespective of the formation of the oxide layer when the layer thickness was less than 5–6 µm. Furthermore, the radiation heat transfer performance was theoretically evaluated taking into consideration the diameter degradation of the fiber core itself. This suggests that the decrease in size of the diameter of the fiber core do not have a significant effect on heat transfer in this study range.