Effects of alumina on densification of a low-temperature cofired crystalllizable glass plus alumina system

The effects of alumina particle size and content on densification of a low-temperature cofired crystallizable K2O-CaO-SrO-BaO-B2O3-SiO2 (TG) glass+alumina system have been investigated. The densification is improved by decreasing alumina content, or increasing alumina particle size. This is attributed to competitive kinetic processes between the viscous flow of the TG glass, and the dissolution of alumina into the TG glass. The dissolution changes the composition of the TG glass to become aluminum-rich, which increases the viscosity of the TG glass, and then slows down the densification kinetics caused by the viscous flow of the TG glass. However, de-densification would take place if the alumina content is not sufficient, or if the alumina particle size is too large because of the bloating of the TG glass.