Glass composition including zirconium, chemically strengthened glass article, glass substrate for magnetic recording media, and method of producing glass sheet

摘要

The present invention provides a glass composition that has excellent heat resistance and ion exchange ability and can be provided with high strength by a chemical strengthening treatment through an ion exchange. This glass composition includes, in terms of mass %: 59 to 68% of SiO2; 9.5 to 15% of Al2O3; 0 to 1% of Li2O; 3 to 18% of Na2O; 0 to 3.5% of K2O; 0 to 15% of MgO; 1 to 15% of CaO; 0 to 4.5% of SrO; 0 to 1% of BaO; 0 to 2% of TiO2; and 1 to 10% of ZrO2. The glass composition of the present invention is suitable for a glass substrate for magnetic recording media and also can be formed as a chemically strengthened glass article through an ion-exchange treatment.