| 학회 | 한국재료학회 |
| 학술대회 | 2009년 봄 (05/21 ~ 05/22, 무주리조트) |
| 권호 | 15권 1호 |
| 발표분야 | 구조재료 |
| 제목 | Oxidation Behavior of Hf-based Ultra High Temperature Ceramics Fabricated by Reactive Hot Pressing |
| 초록 | Recent interest materials for thermal protection systems for hypersonic aerospace vehicles and reusable atmospheric re-entry vehicles have resulted in significant research activity focused on ultra high temperature ceramics (UHTCs). Among the UHTCs, transition metals boride likes hafnium and zirconium are currently accepted as potential candidates due to the high melting temperature (＞3000 oC), high mechanical properties and high thermal shock resistance. In this study, HfB2-SiC was fabricated by ‘in situ’ reactive hot pressing from Hf, B4C and Si powders. The reaction was conducted using two processes, (1) powder reactions at temperature from 900 to 1800 oC and (2) reactive hot pressing between 1800 and 1900 oC. The products from the powder reaction of a 2Hf/1B4C/1Si molar mixture were HfB2, SiC and HfO2. The final reactive hot pressed composition was HfB2, SiC with without any secondary phase. Microstructure analysis indicated that distribution of the in-situ forms HfB2 and SiC phase in the composites are no homogenous and residual porosities were observed. The particle size of HfB2 and SiC are in the particle size ranges of the starting powders of hafnium and silicon. In the oxidation test at 1500 oC, non uniform surface SiO2 distribution was observed. This might due to the non-homogeneous microstructure distribution. To make more homogeneous microstructure and reduce residual porosity, vibration milling of starting powders was conducted. Particle size of starting powders was reduced after 2 hours vibration milling. In this study, starting powder effect on densification and oxidation behavior will be discussed. |
| 저자 | Seung Jun1, Lee2, Do-Kyung1, Kim2 |
| 소속 | 1MSE, 2KAIST |
| 키워드 | Oxidation; UHTCs; Reactive Hot Pressing |
