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US 6,645,889 B2Granted
Glass composition for crystallized glass
AssigneeMinolta Co., Ltd.
InventorsHideki Nagata, Hiroshi Yuki, Toshiharu Mori, Hideki Kawai, Kazuhiko Ishimaru
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Abstract
A polished glass disk medium substrate suitable for use as a substrate for a hard disk, a hard disk containing the substrate and methods for making the substrate. The substrate containing glass forming raw materials may be formed so as to have a Young's modulus of 110 or higher.
Claims38
A polished glass ceramic disk medium substrate comprising crystalline and amorphous phases formed of a mixture of glass forming raw materials comprising
- about 35% to about 50% by weight of SiO2;
- about 5% to about 30% by weight of Al2O3;
- about 10% to about 30% by weight of MgO;
- about 8% to about 20% by weight of TiO2;
- and
- about 0.1% to about 2.4% by weight of Li2O;
- wherein said glass disk medium substrate includes one or more crystalline phases selected from clinoenstatite, magnesium aluminum silicate, Zn2Ti3O8, Zn2TiO4, or a main crystalline phase of clinoenstatite and a secondary crystalline phase of enstatite.
4 more elements
A method of making a glass ceramic disk medium substrate comprising:
- heating glass forming raw materials to a temperature sufficiently high to melt the raw materials;
- forming a disk medium substrate;
- and
- crystallizing the disk medium substrate, wherein said crystallizing comprises heating the disk medium substrate to a temperature, T1, between about 500 and 680° C. to generate crystal nuclei;
- heating at a temperature, T2, between about 680 and about 800° C to grow crystal nuclei;
- and cooling to obtain crystallized glass;
- wherein said glass disk medium substrate is formed of a mixture of glass forming raw materials comprising,
- about 35% to about 50% by weight of SiO2;
- about 5% to about 30% by weight of Al2O3,
- about 10% to about 30% by weight of MgO;
- about 8% to about 20% by weight of TiO2;
- and
- about 0.1% to about 2.4% by weight of Li2O.
10 more elements
Dependencies are inferred from the claim text.