Phase Formation and Rheological Characteristics of LAS Derived from the Monophasic Sol-Gel Route

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J. Korean Ceram. Soc. > Volume 28(5); 1991 > Article

Journal of the Korean Ceramic Society 1991;28(5): 365.

Sol-Gel 반응으로 유도된 LAS의 상 생성과 점성 특성

장현명, 김광수¹, 정창주¹

포항공과대학 재료·금속공학과
¹전남대학교 공과대학 무기재료공학과

Phase Formation and Rheological Characteristics of LAS Derived from the Monophasic Sol-Gel Route

ABSTRACT

LAS (lithium aluminosilicate) sol was synthesized using the hydrolysis-condensation reaction of TEOS, chelated Al(OBus)3 and Li-salt with H2O in alcohol (EtOH+2-Propanol) medium. Effects of important reaction parameters on the properties of sol and gel-derived LAS were examined. The crystallization of the sol-gel derived LAS with ${beta}$-spodumene composition began at ∼600$^{circ}C$, and a series of polymorphic transformations occurred as temperature was increased to 1100$^{circ}C$: amorphous LASlongrightarrowhexagonal LiAl(SiO3)2longrightarrow${beta}$-spodumene. Lowering Li content in the gel enhanced densification and retarded the crystallization significantly. Optimum reaction conditions of LAS sol formation for thin coating applications were derived from rheological measurements, and these can be summarized as: H2O/total alkoxides molar ratio=4, pH=∼2.5, and aging time of ∼250h.