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US 6,635,591 B2Granted
Glass composition for crystallized glass
AssigneeMinolta Co., Ltd.
InventorsHideki Nagata, Hiroshi Yuki, Toshiharu Mori, Hideki Kawai, Kazuhiko Ishimaru
Life of this patent
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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.
Claims35
A polished glass disk substrate formed of a mixture of glass forming raw materials comprising:
- about 65% to about 80% by weight SiO2;
- about 3% to about 15% by weight Al2O3;
- about 0.1% to about 12% by weight MgO;
- about 3% to about 12% by weight Li2O;
- and
- about 5% to about 22% by weight ZnO.
3 more elements
A method of making a glass disk substrate comprising:
- heating glass forming raw materials comprising
- about 65% to about 80% by weight SiO2;
- about 3% to about 15% by weight Al2O3;
- about 0.1% to about 12% by weight MgO;
- about 3% to about 12% by weight Li2O;
- and
- about 5% to about 22% by weight ZnO,
- to a temperature sufficiently high to melt the raw materials;
- forming a disk substrate;
- and
- crystallizing the disk substrate, wherein said crystallizing comprises heating the disk 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.
10 more elements
Dependencies are inferred from the claim text.