Title:
GLASS FOR MAGNETIC RECORDING MEDIUM SUBSTRATES, MAGNETIC RECORDING MEDIUM SUBSTRATE, MAGNETIC RECORDING MEDIUM, AND GLASS SPACER FOR MAGNETIC RECORDING/REPRODUCING APPARATUSES
Document Type and Number:
WIPO Patent Application WO/2018/088563
Kind Code:
A1
Abstract:
Provided is a glass for magnetic recording medium substrates, which is an amorphous oxide glass that has, in mol%, an SiO2 content of 45-68%, an Al2O3 content of 5-20%, a total content of SiO2 and Al2O3 of 60-80%, a B2O3 content of 0-5%, an MgO content of 3-28%, a CaO content of 0-18%, a total content of BaO and SrO of 0-2%, a total content of alkaline earth metal oxides of 12-30%, and a total content of alkali metal oxides of 3.5-15%, while containing at least one oxide selected from the group consisting of Sn oxides and Ce oxides, with the total content of the Sn oxides and the Ce oxides being 0.05-2.00%. The amorphous oxide glass has a glass transition temperature of 625°C or higher, a Young's modulus of 83 GPa or more, a specific gravity of 2.85 or less and an average linear expansion coefficient of 48 × 10-7/°C or more over the temperature range from 100°C to 300°C.
Inventors:
SATO KOICHI (JP)
Application Number:
PCT/JP2017/040833
Publication Date:
May 17, 2018
Filing Date:
November 14, 2017
Export Citation:
Assignee:
HOYA CORP (JP)
International Classes:
C03C3/091; C03C3/085; C03C3/087; G11B5/73
Domestic Patent References:
| WO2001021539A1 | 2001-03-29 |
Foreign References:
| JP2001076336A | 2001-03-23 | |||
| JP2001039732A | 2001-02-13 | |||
| JP2015054794A | 2015-03-23 |
Attorney, Agent or Firm:
SIKS & CO. (JP)
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