Glass-ceramic for information recording disk

Details Glass-ceramic for information recording disk Glass-ceramic for information recording disk

1995-07-28

1996-10-01

Group, Karl

Compositions: ceramic

Ceramic compositions

Devitrified glass-ceramics

501 57, 501 59, 501 67, 501 69, 501 70, C03C 3087, C03C 3093

Patent

active

055610897

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.

REFERENCES:
patent: 4687750 (1987-08-01), Pinckney
patent: 4985375 (1991-01-01), Tanaka et al.
patent: 5028567 (1991-07-01), Gotoh et al.
patent: 5330939 (1994-07-01), Marazzi et al.
patent: 5476821 (1995-12-01), Beall et al.

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