| Autor: |
Liping Liu, Lingwei Yang, Haojun Ma, Jie Luo, Xueren Xiao, Changhao Zhao, Jun Zhang, Guolin Wang, Yiguang Wang |
| Předmět: |
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| Zdroj: |
Journal of Asian Ceramic Societies; Dec2021, Vol. 9 Issue 4, p1506-1515, 10p |
| Abstrakt: |
The emissivity of typical SiC-based thermal protection materials was measured in-situ at a wide temperature range (800 ~ 2300°C) inside a plasma wind tunnel that was capable of simulating hypersonic environments on-ground. Based on it, the evolution mechanism dominated by dynamic oxidation was discussed. The results suggest an emissivity of Cf/SiC 0.84 ~ 0.88 at 858 ~ 1502°C, prior to "temperature jump". If "temperature jump" emerged, the emissivity was decreased rapidly to ≈0.76. The emissivity drop was explained by the microstructural transition of the oxidized surfaces that were triggered by the dissipation of SiO2 oxide scale at 1600 ~ 1900°C. Similar emissivity evolution was observed in SiCf/SiC after "temperature jump". The effect of temperature on the emissivity of ZrB2-SiC was more pronounced. It was increased from ≈0.73 to ≈0.98 at 1009 ~ 1297°C, and was plateaued at 1298 ~ 1497°C, ≈0.98. This was a consequence of the formation of higher percentage SiO2-rich layers. However, due to the dissipation of SiO2 and B2O3, the emissivity of ZrB2-SiC was declined at higher temperatures, from ≈0.98 (≈1497°C) to ≈0.85 (≈1768°C). [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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