The Study on Fabrication of LAS System Ceramics for Thermal Shock Resistance from Silicate Minerals: (II) Preparation of Spodumene Powders with Sillimanite, Kaolin and Pyrophyllite Group Minerals

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J. Korean Ceram. Soc. > Volume 31(7); 1994 > Article

Journal of the Korean Ceramic Society 1994;31(7): 784.

실리케이트 광물을 이용한 내열충격성 LAS계 세라믹스의 제조에 관한 연구: (II) Sillimanite, Kaolin 및 Pyrophyllite족 광물을 이용한 Spodumene 분말합성

박한수, 조경식¹, 문종수

경남대학교 무기재료공학과
¹연세대학교 세라믹공학과

The Study on Fabrication of LAS System Ceramics for Thermal Shock Resistance from Silicate Minerals: (II) Preparation of Spodumene Powders with Sillimanite, Kaolin and Pyrophyllite Group Minerals

ABSTRACT

Though spodumene have a law theraml expension and good thermal shock resistance, its sintering temperature is too close to its melting point in the application for industral purpose. Solving the problems, impurities within the silicate minerals act as a frit during firing, so its densification is expected through enlargement of sintering temperature range. By the heat treatment of starting materials, mixtures of silicate mineral, lithium carbonate, if necessary SiO2 or Al2O3 were added for stoichiometric correction, in the range of 1000~125$0^{circ}C$ for 10 hrs, $beta$-spodumene single phase was synthesized. Mixtures with sillimanite group minerals, $beta$-spodumene was formed at 120$0^{circ}C$ or 125$0^{circ}C$ via intermediate phases of petalite, Li2SiO3 and LiAlO2. For the case of kaolin group minerals, synthesis were completed at 110$0^{circ}C$ for Hadon pink kaolin, 120$0^{circ}C$ for New Zealand white kaolin, When pyrophyllite group minerals were used, those were at the range of 1000~125$0^{circ}C$. Spodumene was completed at lowest temperature, 100$0^{circ}C$ from the mixture of Wando pyrophyllite among them. Microstructure of synthesized powders showed the inrregular lump shape such as densed crystallines.