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Journal of the Korean Ceramic Society 1991;28(8): 626. |
NaCl과 Na$_2$SO$_4$에 의한 SiC 고온 부식에 미치는 Alumina 첨가량의 영향 |
이수영, 고재웅, 김해두 |
한국기계연구소 요업재료실 |
Effect of Alumina Content on the Hot Corrosion of SiC by NaCl and Na2SO4 |
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ABSTRACT |
The specimens for the corrosion test were made by hot-pressing of SiC power with 2 wt% Nl2O3 and 10wt% Al2O3 additions at 200$0^{circ}C$ and 205$0^{circ}C$. The specimens were corroded in 37 mole% NaCl and 63 mole% Na2SO4 salt mixture at 100$0^{circ}C$ up to 60 min. SiO2 layer was formed on SiC and then this oxide layer was dissolved by Na2O ion in the salt mixture. The rate of corrosion of the specimen containing 10 wt% Al2O3 was slower than that of the specimen containing 2 wt% Al2O3. This is due to the presence of continuous grain boundary phase in the specimen containing 10 wt% Al2O3. The oxidation of SiC produced gas bubbles at the SiC-SiO2 interface. The rate of corrosion follows a linear rate law up to 50 min. and then was accelerated. This acceleration is due to the disruption oxide layer by the gas evolution at SiC-SiO2 interface. Pitting corrosion has found at open pores and grain boundaries. |
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