• 한국세라믹학회지
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• 제30권2호
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• pp.157-163
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• 1993

Hot pressing after cold cyclic compaction of Al2O3 powder mixtures containing SiC whiskers or Al2O3 short fibers is studied with emphasis on the effects of cold cyclic compaction. The green density of the mixtures increases as the cycle number increases and the cyclic pressure becomes higher. The higher green density is also obtained by cold cyclic compaction with the lower pressrue than a single stroke cold compaction. To achieve a higher densification during hot pressing, cold cyclic compaction before hot pressing is more efficient compared to the conventional hot pressing process (without cold cyclic compaction). Moreover, a low cyclic pressure did not affect on toughening mechanism by whisker reinforcement.

• 한국세라믹학회지
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• 제34권3호
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• pp.296-302
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• 1997

SiC휘스커를 첨가한 알루미나 분말 기지 복합체의 치밀화에 미치는 상온 반복 압축의 영향을 조사하였다. 반복 압축 응력과 반복 횟수가 증가할수록, 또한 바이어스 압력이 낮을수록 복합체의 초기 성형 밀도가 증가하였으며 가압 및 제하 속도, 반복 속도는 분말의 미끄러짐과 재배열에 큰 영향을 미치지 않음을 알 수 있었다. 상온 반복 압축으로 인한 SiC 휘스커의 파단은 거의 없었으며 휘스커의 배열 방향은 반복 압축 방향에 관계없이 고른 분포를 나타냄으로써 상온 반복 압축 성형이 SiC 휘스커를 첨가한 알루미나 분말 기지 복합체의 초기 성형 밀도를 높일 수 있는 효과적인 방법임을 알 수 있었다.

• 한국세라믹학회지
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• 제30권1호
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• pp.62-68
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• 1993

Densification of alumina powder, grain size and fracture toughness of sintered body by hot pressing after cold compaction were investigated and compared to traditional hot pressing process (without cold cyclic compaction). To achieve a higher densification and to reduce the hot pressing time, hot pressing after cold cyclic compaction was more efficient compared to traditional hot pressing. This phenomenon resulted from the increment of packing densityby the acceleration fo rearrangement of powders under cold cyclic compaction. The grain size of sintered body was only dependent on relative density, and densification during hot pressing was governed by thelattice diffusion. Comprisons of grain size, densification mechanism and fracture toughness resulted from hot pressing after/without cold cyclic compaction showed that a low cyclic pressure may not effect on the fragmentation of alumina powders.