| 摘要 |
PURPOSE: To obtain a disk substrate provided with a property suitable as a magnetic disk for a high density recording by controlling the crystal phase of a crystallized glass to be a prescribed composition and the particle size in the polished surface of a magnetic disk substrate to be a prescribed value. CONSTITUTION: The magnetic disk substrate is composed of the crystallized glass having a crystal structure improved in surface characteristic after polished, a magnetic disk is formed by applying a film forming, process to the substrate and the crystallized glass for producing the magnetic disk substrate has the crystal phase consisting of lithium oxide disilicate (Li2 O.2SiO2 ) andα-quartz (α-SiO2 ). The grown crystal particle ofα-quartz has a spherical particle structure composed of respectively aggregated plural particles and the spherical particle is composed of the crystallized glass having 0.3-3.0μm particle diameter. And the surface roughness Ra of the polished surface of the magnetic disk substrate is controlled to 15-50Å. As a result, the magnetic disk substrate provided with the property suitable as the magnetic disk for high density recording is stably mass-produced at a low cost.
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