As the result of investigating the oxidation resistance and mechanical properties after heat-treatment when grain sizes of SiC were changed in Al_2O_3-SiC-C brick (C = 15 percent, SiC = 10 percent), the following findings were obtained. 1) Using average SiC grain diameter of less than 60pm, oxidation can be inhibited at the temperature of 1300 deg C, and at 1350 deg C in the case of less than 97mu m. In the case of average grain diameter of more than 360jim, no protective film against oxidation can be formed on the surface of brick. 20 There is a tendency that finer grain of SiC yields higher mechanical strength, but the properties are lowered at higher temperature due to volatilization of SiO(g). 3) With an increase in SiC grain diameter, spalling resistance improves, but the difference of SiC grain diameter is presumed to diminish at higher temperature of heat-treatment.
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