| 摘要 |
PROBLEM TO BE SOLVED: To provide a substrate, for an information recording medium, which can deal with the high-speed rotation of a drive and with the thin shape and the high recording density of the record medium and whose reliability is high, to provide a glass, for chemical reinforcement, which is used for the substrate and to provide a magnetic disk which uses the substrate. SOLUTION: A substrate for an information record medium is composed of a chemically reinforced glass obtained from a glass, for chemical reinforcement in which the total content of SiO2 , Al2 O3 and R2 O (where R represents an alkaline metal) exceeds 98 wt. % and whose specific mudulus of elasticity is at 30×10<2> or higher. In a magnetic disk, at least a magnetic layer is formed on the substrate. |
