Structure and Physical Properties of Non-Alkali Multicomponent Glasses

Abstract

Non-alkali multicomponent glasses in the system SiO₂-Al₂O₃-CaO-ZnO-TiO₂-B₂O₃ were prepared by the melt quenching method. The composition range was (in wt%), SiO₂=32.0-38.0, Al₂O₃=9.0-18.0, CaO=17.0-23.0, ZnO=12.0-18.0, TiO₂=10.0-19.0, and B₂O₃=2.0-7.0. Composition dependencies of glass transition temperature T_g, softening temperature T_d, thermal expansion coefficient α, and density ρ were investigated. It was found that an increase in SiO₂, Al₂O₃ or CaO content increases the T_g and T_d but anincrease in ZnO, TiO₂ or B₂O₃ content decreases these characteristic temperatures. The thermal expansion coefficient decreased with an increase in SiO₂, Al₂O₃, ZnO, TiO₂ or B₂O₃ content, but increased by the addition of CaO. It was speculated that alumina and titania are combined with CaO to produce AlO₄ or TiO₄ tetrahedra, which help SiO₂ poor compositions to form a rather stable glass network.