Amorphous carbon substrate for a magnetic disk and a method of manufacturing the same
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United States of America Patent
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Jul 5, 1994
Grant Date -
N/A
app pub date -
Mar 28, 1991
filing date -
Mar 29, 1990
priority date (Note) -
Expired
status (Latency Note)
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Abstract
The surface of a blank for a textured amorphous carbon substrate is polished in a surface with a predetermined surface roughness, and then the blank with a polished surface is heated at a predetermined temperature in an oxidizing atmosphere to form minute irregularities in the polished surface through a reaction expressed by C+O.sub.2 =CO.sub.2 so that the surface is textured in an appropriate surface roughness. A randomly textured amorphous carbon substrate has a randomly textured surface with a surface roughness Ra in the range of 20 to 100 .ANG. and the ratio Ra.sub.2 /Ra.sub.1, where Ra.sub.1 is the surface roughness with respect to a circumferential direction, and Ra.sub.2 is the surface roughness with respect to a radial direction, in the range of 0.75 to 1.25 .ANG.. A concentrically textured amorphous carbon substrate has a concentrically textured surface with a surface roughness Ra in the range of 30 to 100 .ANG. or in the range of 40 to 200 .ANG., and the ratio Ra.sub.2 /Ra.sub.1 of 1.75 or greater.
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