| 摘要 |
PURPOSE:To realize a good medium characteristic by coating a nonmagnetic NiP layer on the surface of an aluminum alloy plate on the surface of an aluminum alloy plate and providing an oxide layer of NiP on the surface of the NiP layer. CONSTITUTION:A nonmagnetic hard NiP layer is formed on the surface of an aluminum alloy disc plate and thereafter the surface is polished to a specular surface. Such plate is put into a plasma oxidizing device and is thereby oxidized. A Co-added gamma-Fe2O3 film is formed on the base plate A manufactured in such a way by a sputtering method (formation of an Fe3O4 film conversion to the gamma-Fe2O3 film by thermal oxidation). The medium characteristics better than the case in which a magnetic medium is directly formed on the underlying surface of the NiP are thus realized and the manufacture of a ferrite film magnetic disc and Co-Cr vertical medium having the high quality (non-defectiveness) of the underlying base plate for the NiP layer and good magnetic characteristic in combination is made possible.
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