| 摘要 |
PROBLEM TO BE SOLVED: To develop a glass substrate having high Young's modulus as the glass substrate for a hard disk in order to suppress deflection at the time of high-speed rotation of a disk, to avoid collision of a head against the disk and to attain stable reading/writing. SOLUTION: The glass substrate for an information recording medium is amorphous and has Young's modulus of >=8500 kg/mm2. The substrate consists of SiO2-Al2O3-B2O3 series amorphous components comprising, in particular, 5 to 75 wt.% SiO2, 5 to 35 wt.% Al2O3, 1 to 20 wt.% B2O3, 5 to 15 wt.% alkali component (including at least one kind among Na2O, K2O and Li2O) and 1 to 20 wt.% MgO as a RO component. Further as another additional component, 0.05 to 10.0 wt.% of at least one kind of oxide of Ti, Zr, Y, La, V, Ce, W, Sc, Nd, Eu, Er, Sm, Pr, Fe, As, Sb may be included.
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