| 摘要 |
This invention is directed to the production of unitary, transparent glass articles demonstrating exceptionally high flexural and impact strengths composed of an interior portion and an integral surface compression layer. The articles are prepared by contacting glass bodies consisting essentially, in mole percent, of 14-24% R2O, wherein R2O consists of 0-5% Li2O, 0-5% K2O, and the remainder Na2O, 17-21% Al2o3, 45-60% SiO2, 3-6% TiO2 and/or ZrO2, and 0-2% P2O5, the sum of those components constituting at least 85% of the total composition, at a temperature above the annealing point of the glass with a source of Li+ ions to replace at least part of the Na+ ions and, if present, K+ ions in a surface layer with a corresponding amount of Li+ ions and to react the Li+ ions with Al2O3 and SiO2 in the surface layer to form crystallites of beta-quartz solid solution nucleated by the TiO2 and/or ZrO2. |
