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US 11,884,584 B2Granted
Glass for magnetic recording medium substrate or for glass spacer for magnetic recording and reproducing
AssigneeHoya Corporation
InventorsKoichi Sato, Kazuaki Hashimoto
Life of this patent
Estimating the term…
Abstract
A glass, which is a glass for a magnetic recording medium substrate or for a glass spacer for a magnetic recording and reproducing apparatus, is an amorphous oxide glass. 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 Na2O content is 0 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 Na2O content is 0 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 is equal to or less than 10 mol %;
- a B2O3 content ranges from 0 mol % to 4 mol %;
- a CaO content is 0 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
Dependencies are inferred from the claim text.