- Patent Title: GLASS FOR MAGNETIC RECORDING MEDIUM SUBSTRATE OR FOR GLASS SPACER TO BE USED IN MAGNETIC RECORDING/REPRODUCING DEVICE, MAGNETIC RECORDING MEDIUM SUBSTRATE, MAGNETIC RECORDING MEDIUM, GLASS SPACER TO BE USED IN MAGNETIC RECORDING/REPRODUCING DEVICE, AND MAGNETIC RECORDING/REPRODUCING DEVICE
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Application No.: US17784528Application Date: 2020-12-11
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Publication No.: US20230192530A1Publication Date: 2023-06-22
- Inventor: Koichi SATO , Kazuaki HASHIMOTO
- Applicant: HOYA CORPORATION
- Applicant Address: JP Shinjuku-ku,Tokyo
- Assignee: HOYA CORPORATION
- Current Assignee: HOYA CORPORATION
- Current Assignee Address: JP Shinjuku-ku,Tokyo
- Priority: JP 19225368 2019.12.13
- International Application: PCT/JP2020/046405 2020.12.11
- Date entered country: 2022-06-10
- Main IPC: C03C3/095
- IPC: C03C3/095 ; C03C3/087 ; G11B5/72 ; G11B5/235
Abstract:
Provided is a glass for a magnetic recording medium substrate or for a glass spacer for a magnetic recording/reproducing apparatus, in which the total content of Li2O, Na2O, K2O, B2O3, and ZnO (Li2O+Na2O+K2O+B2O3+ZnO) is in a range of 0 mol % or more and 3 mol % or less, the mole ratio of the total content of Al2O3 and MgO relative to the total content of SiO2 and CaO [(Al2O3+MgO)/(SiO2+CaO)] is in a range of 0.30 or more and 0.6 or less, the total content of SiO2 and Al2O3 (SiO2+Al2O3) is in a range of 64 mol % or more and 85 mol % or less, and the total content of SiO2, Al2O3, MgO, and CaO (SiO2+Al2O3+MgO+CaO) is in a range of 87 mol % or more and 98 mol % or less.
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