Effect of BaO on crystallization, sintering, and properties of MgO-Al2O3-SiO2 glass-ceramics

The effect of BaO on the crystallization, sintering, and properties of MgO-Al2O3-SiO2 glass-ceramics was investigated. The sintering kinetics suggested that doping BaO decreased the sintering activation energy and thus enhanced the densification of MAS glass-ceramics. DSC demonstrated that BaO increased the crystallization temperature of indialite and inhibited the precipitation of indialite. XRD indicated that the addition of BaO promoted the formation of (MgAl2Si3O10)(0.6) and even stabilized the existence of (MgAl2Si3O10)(0.6) phase. The precipitation of (MgAl2Si3O10)(0.6) with high thermal expansion coefficient increased the internal stress and the mosaic structure of co-existed indialite and (MgAl2Si3O10)(0.6) markedly improved mechanical properties. MAS glass-ceramics with 3 wt% BaO sintered at 950 degrees C showed good properties: epsilon(r) = 6.01, tan delta = 2.5 x 10(-3), sigma = 310 MPa, phi = 109.3 GPa, and alpha = 4.52 x 10(-6)/degrees C.

Automated summary

The addition of BaO improves the densification and mechanical properties of MgO-Al2O3-SiO2 glass-ceramics, and alters their crystallization behavior and phase structure.