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US 11,688,424 B2Granted
Glass for magnetic recording medium substrate, magnetic recording medium substrate, magnetic recording medium, glass spacer for magnetic recording and reproducing apparatus, and magnetic recording and reproducing apparatus
AssigneeHoya Corporation
InventorsKoichi Sato, Kazuaki Hashimoto
Life of this patent
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Abstract
Provided is a glass for a magnetic recording medium substrate, which is an amorphous glass, in which an SiO2 content is in a range of 54 mol % or more and 62 mol % or less, an MgO content is in a range of 15 mol % or more and 28 mol % or less, an Li2O content is in a range of 0.2 mol % or more, and an Na2O content is in a range of 5 mol % or less.
Claims12
A glass for a magnetic recording medium substrate or for a glass spacer for a magnetic recording and reproducing apparatus, which is an amorphous glass,
- wherein an SiO2 content is in a range of 54 mol % or more and 62 mol % or less,
- an MgO content is in a range of 15 mol % or more and 28 mol % or less,
- an Li2O content is in a range of 0.2 mol % or more,
- an Na2O content is in a range of 5 mol % or less,
- a mole ratio of the total content of SiO2 and MgO relative to the Li2O content [(SiO2+MgO)/Li2O] is 13 or more, as well as
- wherein a mole ratio of the total content of Al2O3 and CaO relative to the MgO content [(Al2O3+CaO)/MgO] is 0.80 or more, and/or
- a mole ratio of the MgO content relative to a CaO content (MgO/CaO) is 8 or more.
4 more elements
Dependencies are inferred from the claim text.