Cerammable mineral glass, glass-ceramic articles and preparation thereof

Abstract

The present invention relates to novel mineral glasses which are cerammable and which have a composition, expressed in percentages by weight of oxides, consisting essentially of: SiO2 65–70; Al2O3 18–20.5; Li2O 2.5–3.8; MgO 0.55–1.5; ZnO 1.2–2.8; BaO 0–1.4; SrO 0–1.4; with BaO+SrO 0.4–1.4; with MgO+BaO+SrO 1.1–2.3; Na2O 0–<1; K2O 0–<1; with Na2O+K2O 0–<1; with ⁢ ⁢ 2.8 ⁢ ⁢ Li 2 ⁢ O + 1.2 ⁢ ZnO 5.2 ⁢ ⁢ MgO > 1.8 ; TiO2 1.8–3.5; ZrO2 0.8–2.5; with ⁢ ⁢ 2.2 < TiO 2 ZrO 2 < 4.5 ; ⁢ preferably ⁢ ⁢ 2.3 < TiO 2 ZrO 2 < 4.5 ; and, optionally, an effective, non-excess amount of at least one fining agent. The present invention also relates to glass-ceramic articles made from such glass as well as processes for making such glass-ceramic articles.

Dependencies are inferred from the claim text.