Glass manufacturing – Processes – With chemically reactive treatment of glass preform
Reexamination Certificate
2005-06-20
2009-12-01
Tarazano, D. Lawrence (Department: 1794)
Glass manufacturing
Processes
With chemically reactive treatment of glass preform
C428S846900, C428S848600, C501S123000
Reexamination Certificate
active
07624594
ABSTRACT:
The present invention is a magnetic recording medium substrate made of amorphous glass of B2O3—Al2O3—SiO2—Li2O type, wherein a chamfer is formed between an edge face at an outer circumference side or an inner circumference side of the substrate and a principal plane of the substrate, and a content of sodium and potassium at a surface area of the inner or outer circumference side edge face and a surface area of the chamfer is greater than a mean content of sodium and potassium of the magnetic recording medium substrate. With the present invention, it is possible to prevent generation of projections on a magnetic film, a protective film or the like due to movement of lithium ions in a magnetic recording medium substrate made of amorphous glass which includes lithium.
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Translation JA 11-191212.
Translation JA 2001-180969.
Aida Katsuaki
Matsumura Yukihisa
Falasco Louis
Showa Denko K.K.
Sughrue & Mion, PLLC
Tarazano D. Lawrence
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