HIGH-STRENGTH POLYCRYSTALLINE GLASS AND METHOD OF ITS PRODUCING Russian patent published in 2001 - IPC

FIELD: glass ceramic materials. SUBSTANCE: polycrystalline glass has the following components, wt.-%: SiO₂, 57.0-70.0; Li₂O, 12.7-19.0; NaPO₃, 2.0-4.0; K₂O, 1.7-2.5; CaF₂, 0.9-1.2; LiF, 4.0-8.0; CeO₂, 0.1-1.0; TiO₂ 0.1-9.0; CaO, 0.1-4.0; MnO/MnO₂ = 0.1-4.0; Al₂O₃, 0.1-4.0. High-strength polycrystalline glass is founded from lithium-silicate glass at 1300-1350 C, formation of specimens to cold form is carried out from temperature 1300-1350 C, annealing at temperature 400-420 C and thermal treatment after annealing is carried out by two-stage regimen: temperature rise to 480-520 C, keeping for 2-3 h, temperature rise to 680-720 C at the rate 1-4 degrees per minute, keeping at indicated temperature for 1-2 h followed by natural cooling to the room temperature. Obtained low-melting polycrystalline glass exhibits high strength parameters in combination with low density and can be used under conditions of extreme loadings. EFFECT: improved quality and properties of glass ceramic. 2 cl, 1 tbl