Effects of Dissolved Ca from Plaster Mold During Slip Casting on the Microstructure and Fracture Toughness of Sintered Alumina

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J. Korean Ceram. Soc. > Volume 28(12); 1991 > Article

Journal of the Korean Ceramic Society 1991;28(12): 1019.

석고 몰드에서 용출된 Ca이 주입성형 알루미나 소결체의 미세구조 및 파괴인성에 미치는 영향

박재관, 임동기, 김인태, 김윤호

한국과학기술연구원 정밀요업실

Effects of Dissolved Ca from Plaster Mold During Slip Casting on the Microstructure and Fracture Toughness of Sintered Alumina

ABSTRACT

The effect of dissolved Ca ion from plaster mold during slip casting on the microstructure and fracture toughness of high-purity sintered alumina were investigated. When the alumina slip containing 1000 ppm MgO was casted on a calcined alumina mold, the sintered compact had a homogeneous microstructure with equiaxed grains. However, when the same slip was casted on a plaster mold, the sintered compact consisted of the mixture of equiaxed and elongated grains. This inhomogeneous microstructure was also observed in the sintered alumina doped with 100o ppm MgO and 100 ppm CaO whose compact was prepared on the calcined alumina mold indicating that the inhomogeneity was caused by CaO. It was found that the specimen containing both MgO and CaO had higher fracture toughness than that containing MgO only. The enhanced fracture toughness by CaO is probably due to the crack deflection along the boundaries of the elongated grains.