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US 11,447,414 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
Estimating the term…
Abstract
Provided is a glass for a magnetic recording medium substrate, which is an amorphous oxide glass, in which an SiO2 content ranges from 56 mol % to 80 mol %, an Li2O content ranges from 1 mol % to 10 mol %, a B2O3 content ranges from 0 mol % to 4 mol %, a total content of MgO and CaO (MgO+CaO) ranges from 9 mol % to 40 mol %, and the oxide glass has a specific gravity of 2.75 g/cm3 or less, a glass transition temperature of 650° C. or higher, and a Young's modulus of 90 GPa or more.
Claims20
A glass,
- which is a glass for a magnetic recording medium substrate or for a glass spacer for a magnetic recording and reproducing apparatus,
- which is an amorphous oxide glass,
- wherein an SiO2 content ranges from 56 mol % to 80 mol %;
- an Li2O content ranges from 1 mol % to 10 mol %;
- a B2O3 content ranges from 0 mol % to 4 mol %;
- a MgO content is less than 14 mol %;
- a total content of MgO and CaO (MgO+CaO) ranges from 9 mol % to 40 mol %;
- and
- the oxide glass has a specific gravity of 2.75 g/cm3 or less, a glass transition temperature of 650° C. or higher, and a Young's modulus of 90 GPa or more.
6 more elements
A glass,
- which is a glass for a magnetic recording medium substrate or for a glass spacer for a magnetic recording and reproducing apparatus,
- which is an amorphous oxide glass,
- wherein an SiO2 content ranges from 56 mol % to 80 mol %;
- an Li2O content ranges from 1 mol % to 10 mol %;
- a B2O3 content ranges from 0 mol % to 4 mol %;
- a MgO content is less than 14 mol %;
- a total content of MgO and CaO (MgO+CaO) ranges from 9 mol % to 40 mol %;
- a mole ratio of a total content of SiO2 and ZrO2 relative to an Al2O3 content ((SiO2+ZrO2)/Al2O3) ranges from 2 to 13;
- and
- the oxide glass has a glass transition temperature of 650° C. or higher, and a Young's modulus of 90 GPa or more.
7 more elements
Dependencies are inferred from the claim text.