Glass for information recording medium substrate, glass substrate for information recording medium and magnetic disk
US8168313B2 · kind B2 · utility
20Cited by
9References
20Claims
0Family size
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Key dates
| Filing date | Mar 16, 2010 |
| Grant date | May 1, 2012 |
| Priority date | — |
| Expiry date | Mar 16, 2030 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B5/73921
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
A glass for an information recording medium substrate, which comprises, as represented by mol % based on the following oxides, from 61 to 72% of SiO2, from 3 to 11% of Al2O3, from 0 to 14.3% of Li2O, from 0 to 22% of Na2O, from 0 to 22% of K2O, from 4 to 13% of MgO, from 0 to 6% of TiO2 and from 0 to 5% of ZrO2, provided that the total content of Li2O, Na2O and K2O (R2O) is from 10 to 22%, and (a) the ratio of the content of Li2O to R2O (Li2O/R2O) is at most 0.52, (b) the ratio of the content of Na2O to R2O (Na2O/R2O) is at least 0.35, or (c) the ratio of the content of K2O to R2O (K2O/R2O) is at least 0.45.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.