- Patent Title: 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
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Application No.: US18323378Application Date: 2023-05-24
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Publication No.: US12211533B2Publication Date: 2025-01-28
- Inventor: Koichi Sato , Kazuaki Hashimoto
- Applicant: HOYA CORPORATION
- Applicant Address: JP Tokyo
- Assignee: HOYA CORPORATION
- Current Assignee: HOYA CORPORATION
- Current Assignee Address: JP Tokyo
- Agency: Global IP Counselors, LLP
- Priority: JP2019-134578 20190722,JP2019-205993 20191114
- Main IPC: G11B5/73
- IPC: G11B5/73 ; C03C3/087
Abstract:
In an amorphous glass, an SiO2 content is in a range of 56 mol % or more. 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 total content of Al2O3, MgO, and CaO (Al2O3+MgO+CaO) is 36.50 mol % or less. The total content of SiO2, MgO, Li2O, Al2O3, and CaO (SiO2+MgO+Li2O+Al2O3+CaO) is 97.5 mol % or more. A mole ratio of the total content of SiO2 and MgO relative to the Li2O content [(SiO2+MgO)/Li2O] is 13 or more. A mole ratio of a CaO content relative to a total content of Al2O3 and MgO [CaO/(Al2O3+MgO)] is 0.10 or less.
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