The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 01, 1996
Filed:
Jul. 28, 1995
Kabushiki Kaisya Ohara, , JP;
Abstract
Glass-ceramic for information recording disks have a crystalline structure suitably used for substrate materials and the like for magnetic disks and magneto-optic disks as well as have improved surface characteristics obtained by polishing the glass, and besides the base glass thereof is excellent in melting properties and moldability thereof. The base glass composition consists essentially of ingredients of SiO.sub.2 -Al.sub.2 O.sub.3 -ZnO-MgO-CaO-SrO-BaO-TiO.sub.2 system. The main crystalline phase of the glass-ceramic produced by heat-treating the base glass having a viscosity of log .eta.=3.0 poise or less at 1250.degree. C. is gahnite, a size of the crystal grain is within a range of from 50 to 1000 Angstrom, and a degree of surface roughness (Ra) of the polished glass-ceramic is within a range of from 0.5 to 9.0 Angstrom.