BARC/PUB/2011/1158

 
 

Some studies on the phase formation and kinetics in TiO2 containing lithium aluminum silicate glasses nucleated by P2O5

 
     
 
Author(s)

Ananthanarayanan, A.; Dixit, A.; Lenka, R. K.; Purohit, R. D.; Shrikhande, V. K.; Kothiyal, G. P.

Source

Journal of Thermal Analysis and Calorimetry, 2011. Vol. 106 (3): pp. 839-844

ABSTRACT

Lithium aluminum silicate (LAS) glasses of compositions (wt%) 10.6Li2O–71.7SiO2–7.1Al2O3–4.9K2O–3.2B2O3–1.25P2O5–1.25TiO2 were prepared by the melt quench technique. Crystallization kinetics was investigated by the method of Kissinger and Augis–Bennett using differential thermal analysis (DTA). Based on the DTA data, glass ceramics were prepared by single-, two-, and three-step heat treatment schedules. The interdependence of different phases formed, microstructure, thermal expansion coefficient (TEC) and microhardness (MH) was investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), thermo-mechanical analysis (TMA), and microhardness (MH) measurements. Crystallization kinetics revealed that Li2SiO3 is the kinetically favored phase with activation energy of 91.10 kJ/mol. An Avrami exponent of n = 3.33 indicated the dominance of bulk crystallization. Based upon the formation of phases, it was observed that the two-stage heat treatment results in highest TEC glass ceramics. The single-step heat treatment yielded glass ceramics with the highest MH.

 
 
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