Crystallization, microstructures and properties of low temperature co-fired CaO-Al2O3-SiO2 glass-ceramic

CaO-Al2O3-SiO2 glass-ceramic were prepared by melt quenching technique. The crystallization behavior and properties were studied by means of a non-isothermal, thermal analysis technique, X-ray diffraction and scanning electron microscopy. The influence of sintering temperature on phase formation, microstructure, bending strength, dielectric and thermal properties were determined. The activation energy of crystallization and the Avrami parameter were also discussed. The X-ray diffraction results show that SiO2 phase could be found in all samples and CaSiO3 and anorthite phases could only be observed in the samples sintered at above 875A degrees C. The densification of glass-ceramic starts at 730A degrees C after the liquid glass is formed and stops at 803A degrees C. Complete densification was achieved at 875A degrees C and the highest mechanical strength was obtained at 850A degrees C, but density significantly decreased at higher temperatures. The coefficient of thermal expansion and the dielectric constant increase with the increasing sintering temperature. The value of the Avrami parameter (n) is similar to 1.6 and the apparent activation energy (E) is 298 kJ/mol.