Glass-ceramic composition for recording disk substrate
AssigneeMinolta Co., Ltd.
InventorsHideki Nagata, Toshiharu Mori, Hiroshi Yuki, Hideki Kawai, Akira Sugimoto, Kazuhiko Ishimaru
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Abstract
A glass ceramics composition for recording disk substrate contains, essentially, expressed in terms of weight percent on the oxide basis, from 47.5 to 58 wt % of SiO2, from 10 to 30 wt % of Al2O3, from 10 to 30 wt % of MgO, and from 0.1 to 2.8 wt % of ZrO2.
Claims24
A glass ceramics composition for recording disk substrate consisting essentially, expressed in terms of weight percent on an oxide basis, of
- from 47.5 to 58 wt % of SiO2,
- from 10 to 30 wt % of Al2O3,
- from 10 to 30 wt % of MgO, and
- from 0.1 to 2.8 wt % of ZrO2,
- wherein the glass ceramic has a main crystalline phase containing magnesium alumina silicate as a predominant constituent.
A glass ceramic recording disk substrate, wherein the glass ceramic is prepared from a composition which consists essentially, expressed in terms of weight percent on an oxide basis, of
- from 47.5 to 58 wt % of SiO2,
- from 10 to 30 wt % of Al2O3,
- from 10 to 30 wt % of MgO, and
- from 0.1 to 2.8 wt % of ZrO2,
- wherein the glass ceramic has a main crystalline phase containing magnesium alumina silicate as a predominant constituent.
Dependencies are inferred from the claim text.