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US 2001/0056022 A1Published application
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 disk medium substrate formed of a mixture of glass forming raw materials comprising
- about 35% to about 50% by weight SiO2;
- about 5% to about 20% by weight Al2O3;
- about 9% to about 25% by weight MgO;
- about 0.1% to about 12% by weight TiO2;
- about 0.1% to about 12% by weight Li2O;
- and
- about 5% to about 22% by weight ZnO.
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A method of making a glass 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 crystalized glass.
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Dependencies are inferred from the claim text.