Magnetic recording disc and process for producing the same

Details Magnetic recording disc and process for producing the same Magnetic recording disc and process for producing the same

1986-11-19

1989-02-28

Robinson, Ellis P.

Stock material or miscellaneous articles

Circular sheet or circular blank

Recording medium or carrier

20419215, 20419216, 2041922, 20419223, 427128, 427129, 427130, 427131, 427132, 428 65, 428141, 428426, 428433, 4283184, 4283191, 428428, 428694, 428704, 428900, G11B 582, G11B 572

Patent

active

048084557

ABSTRACT:
An improved magnetic recording disc comprising: a substrate member of an alumina-based ceramic material having micropores of 5 .mu.m or below and having a relative theoretical density of 90% or higher; a glass coating layer of a thickness of 3 to 200 .mu.m with a surface roughness (R.sub.z) of 180 angstroms or below, and being free from micropores and strain; a magnetic thin film formed on the surface of the glass coating layer; and a protective film formed thereon.
A process for production of the magnetic recording disc comprises: forming a glass coating layer to a thickness of 5 to 220 .mu.m on the surface of an alumina-based ceramic substrate having micropores of 5 .mu.m or below and a relative theoretical density of at least 90%; then subjecting the glass coating layer to mechanochemical polishing to a layer thickness of 3 to 200 .mu.m, to make free from micropores and strain, and to have a surface roughness (R.sub.z) of 180 angstroms or below; and further coating the surface of the glass coating layer with a magnetic thin film and a protective film.

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