Magnetic-disk glass substrate
AssigneeHoya Corporation
InventorShuhei Azuma
Life of this patent
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Abstract
An edge surface of a magnetic-disk glass substrate containing an alkali metal component as a glass composition is a mirror surface, and in a bearing ratio curve of roughness cross-sectional areas obtained by measuring a surface roughness of the edge surface obtained by etching the edge surface by 2.5 μm, a roughness percentage when a bearing ratio of a roughness cross-sectional area is 50% is 40% or more.
Claims20
A magnetic-disk glass substrate containing an alkali metal component as a glass composition, the magnetic-disk glass substrate comprising:
- an edge surface that is a mirror surface,
- the edge surface including a surface with a roughness percentage that is 40% or more and about 67% or less when a bearing ratio of a roughness cross-sectional area is 50%, in a bearing ratio curve of roughness cross-sectional areas obtained when a surface roughness of the edge surface obtained by etching the edge surface by 2.5 μm is measured.
A glass substrate containing an alkali metal component as a glass composition, the glass substrate comprising:
- an edge surface that is a mirror surface,
- the edge surface including a surface with a roughness percentage that is 40% or more and about 67% or less when a bearing ratio of a roughness cross-sectional area is 50%, in a bearing ratio curve of roughness cross-sectional areas obtained when a surface roughness of the edge surface obtained by etching the edge surface by 2.5 μm is measured.
Dependencies are inferred from the claim text.