Composition and crystallization kinetics of R 2O–Al 2O 3–SiO 2 glass–ceramics

Abstract

The crystallization behavior and microstructure of R 2O–Al 2O 3–SiO 2 (R means K, Na and Li) glass were investigated by means of differential scanning calorimeter (DSC), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The crystallization kinetic parameters including the crystallization apparent activation energy ( E a), the Avrami parameter ( n), glass transition temperature ( T g) and the activity energy of glass transition ( E t) were also measured with different methods. The results have shown that: the DSC traces of composition A parent glass have two different precipitation crystallization peaks corresponding to E a1(A) = 151.4 kJ/mol (Li 2SiO 3) and E a2(A) = 623.1 kJ/mol (Li 2Si 2O 5), the average value of n = 1.70 (Li 2Si 2O 5) for the surface crystallization and E t(A) = 202.8 kJ/mol. And E a(B) = 50.7 kJ/mol (Li 2SiO 3), the average value of n = 3.89 (Li 2SiO 3) for the bulk crystallization and E t (B) = 220.4 kJ/mol for the composition B parent glass. Because of the content of R 2O is bigger than composition A, composition B parent glass has a lower E a, T g and a larger n, E t.