Effect of complex nucleation agents on preparation and crystallization of CaO-MgO-Al2O3-SiO2 glass-ceramics for float process

Abstract

CaO-MgO-Al2O3-SiO2 flat glass-ceramic produced by float process with excellent properties can be widely used in architectural decoration, electronics, environmental protection and other fields. The effects of complex nucleation agents (TiO2, CaF2 and P2O5) on melting and crystallization behaviors of glasses were investigated by DSC, XRD, SEM, FESEM, Raman spectroscopy and viscosity test. The results showed that the practical melting temperature and forming temperature of T specimen doped with 5wt% TiO2 were about 1489°C and 1286°C, and those of TF specimen doped with 5wt% TiO2 and 2wt% CaF2 were decreased to about 1463°C and 1260°C, respectively. However, the practical melting temperature, forming temperature and Tp of TP and TFP specimens doped with 5wt% TiO2+2wt% P2O5 and 5wt% TiO2+2wt% CaF2+2wt% P2O5 were shifted to higher temperature, which resulted in the difficulty of float process and crystallization. Diopside as the major crystalline phase was precipitated in four specimens with different nucleation agents. Furthermore, the crystallinity of TF specimen was increased with the addition of 2wt% CaF2. Nevertheless, the addition of P2O5 resulted in the decrease of diopside content and the precipitation of calcium phosphate.