GLASS MATERIAL FOR INFORMATION RECORDING GLASS SUBSTRATE, INFORMATION RECORDING GLASS SUBSTRATE, INFORMATION RECORDING DISK, AND HARD DISK DRIVE

摘要

PROBLEM TO BE SOLVED: To suppress lowering of strength caused by microcracks and to reduce the generation of cracks at the time of collision of a magnetic head by improving toughness of a glass material for an information recording glass substrate.;SOLUTION: The glass material for the information recording glass substrate has a composition containing, by mass, 5-15% Na₂O, 0-10% Li₂O, 5-15% Al₂O₃, 0-6% CaO, 2-10% TiO₂, and 53-75% SiO₂, and further 0.5-10%, expressed in terms of Nb₂O₅ or V₂O₅, of an Nb oxide and/or V oxide, or 5-15% Na₂O, 0-10% Li₂O, 5-15% Al₂O₃, 0-6% CaO, 2-6% TiO₂, 0-5% ZrO₂ and 53-75% SiO₂, and further containing 0.5-10%, expressed in terms of Nb₂O₅ or V₂O₅, of an Nb oxide and/or V oxide.;COPYRIGHT: (C)2005,JPO&NCIPI