effect of Heating Rate on the Mechanical Properties in the Crystallization of <tex>$Li_2O$</tex>.<tex>$2SiO_2$</tex> Glass

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J. Korean Ceram. Soc. > Volume 33(7); 1996 > Article

Journal of the Korean Ceramic Society 1996;33(7): 809.

$Li_2O$.$2SiO_2$유리의 결정화에서 승온속도가 기계적 특성에 미치는 영향

최병현, 고경현¹, 안재환¹, 지응업

국립기술품질원 요업기술원
¹아주대학교 재료공학과

effect of Heating Rate on the Mechanical Properties in the Crystallization of $Li_2O$.$2SiO_2$ Glass

ABSTRACT

When Li2O.2SiO2 glass was crystallized between the temperature of maximum nucleation and the temperature of maximum crystal growth it was found that the control of heating rate had serious effect on the crystallinity and microstructure and the greatly changed physical properties. Density and elastic modulus tends to increase but thermal expansion coefficient decreased with increased crystallinity. When heating rate between the tempe-rature of maximum nucleation and the temperature of maximum crystal growth was 10~5$0^{circ}C$/hr. crystallinity was increased to result in the increment of strength. When nuclation was done at 44$0^{circ}C$ for 5 hours and the temperature of crystal growth was held at 575$^{circ}C$ strength was increased until crystallinity reached 65% and strength was decreased with higher crystallinity. These phenomena could be explained that even for the same crystallinity different heat rates resulted in different number and size of cracks.

Key words: Heating rate, Microstructure, Crystallinity, Strength, Crack