Fabrication of Low-Shrinkage Reaction-Bonded Alumina Ceramics

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J. Korean Ceram. Soc. > Volume 29(6); 1992 > Article

Journal of the Korean Ceramic Society 1992;29(6): 419.

저수축 반응소결 알루미나 세라믹스의 제조

박정현, 이현권, 정경원, 염강섭

연세대학교 세라믹공학과

Fabrication of Low-Shrinkage Reaction-Bonded Alumina Ceramics

ABSTRACT

Fabrication possibility of low-shrinkage alumina without oxidation and wetting agent was presented on the basis of observation about oxidation behavior, microstructure and physical characteristics of such reaction agents free Al2O3-Al system. The composition less than Al 10w/o where Al can act as a sintering agent for Al2O3 was excluded. Under the condition of present experiments oxidation of Al2O3-Al system was dependent not on holding time but mainly on oxidation temperature. In thes case of Al powder not comminuted effectively during powder mixing of Al2O3-Al, columnar structure which would act as a hindrance to the densification during sintering developed more during oxidation with higher Al contents, and which made the fabrication of low-shrinkage Al2O3 ceramics impossible. If Al powder was comminuted effectively due to co-mixed Al2O3 characteristics, densification was improved because of no columnar structure and made the fabrication of sintered body with -2.7% dimensional change and 81% relative density possible. As a result, it is possible to fabricate dense low-shrinkage Al2O3 ceramics without oxidation and wetting agent under conditions such as smaller particle size of Al, Al contents below 50v/o, higher green density of Al2O3-Al compact and the use of Al2O3 powder used for high-density ceramics.