β-spodumene glass-ceramic materials and process for making the same

摘要

The present invention relates to glass-ceramic materials, processes for making the same and articles comprising the same. The glass-ceramic material has a composition, by weight of the total composition, comprising 55-68% SiO₂; 18-24% Al₂O₃; 3.3-4.1% Li₂O; 1.5-4.0% ZnO; 1.5-5.0% MgO; 2-5% TiO₂; 0-2% ZrO₂; 0-5% B₂O₃; 0-8% P₂O₅; 0-2% Na₂O, 0-2% K₂O; and at least one component resulting from an effective amount of at least one fining agent; wherein: the total of B₂O₃ and P₂O₅ is at least 1.5% by weight, the total of MgO and ZnO is at least about 3.5% by weight, the total of Na₂O and K₂O is less than about 3.0% by weight, the total of P₂O₅, B₂O₃, Na₂O and K₂O is less than about 11% by weight, the weight ratio of the sum total of Na₂O+K₂O to the sum total of P₂O₅+B₂O₃ ; $$ \left(\frac{{\mathrm{Na}}_{2}O+K_{2}O}{B_2{O}_3+P_2{O}_5}\right)$$is less than about 0.5; advantageously the total of P₂O₅, B₂O₃, Na₂O and K₂O is less than about 9% by weight and the total of Na₂O ad K₂O is less than about 2% by weight; and more advantageously the total of P₂O₅, B₂O₃, Na₂O and K₂O is less than about 7% by weight and the total of Na₂O ad K₂O is less than about 1% by weight. The glass-ceramic material comprises β-spodumene solid solution as the predominant crystalline phase.