Method for Estimating Continuous Cooling Transformation Curves of Glasses
A method is proposed for estimating the critical cooling rate and continuous cooling transformation curve (CCT) from isothermal TTT data of glasses. The critical cooling rates and CCT curves for a group of lithium disilicate glasses containing different amounts of Pt as nucleating agent estimated through this method are compared with the experimentally measured values. By analysis of the experimental and calculated data of the lithium disilicate glasses, a simple relationship between the crystallised amount in the glasses during continuous cooling, X, and the temperature of undercooling, ΔT, was found to be X=AR-4exp(BΔT), where ΔT is the temperature difference between the theoretical melting point of the glass composition and the temperature in discussion, R is the cooling rate, and A and B are constants. The relation between the amount of crystallisation during continuous cooling and isothermal hold can be expressed as (X cT/XiT)=(4/B)4ΔT-4. X cT here stands for the crystallised amount in a glass during continuous cooling for a time t when the temperature comes to T, and X iT for the crystallised amount during isothermal hold at temperature T for a time t.
D. Zhu et al., "Method for Estimating Continuous Cooling Transformation Curves of Glasses," Physics and Chemistry of Glasses: European Journal of Glass Science and Technology Part B, vol. 47, no. 3, pp. 271-277, Society of Glass Technology, Jun 2006.
Materials Science and Engineering
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