| 摘要 |
PURPOSE:To obtain a magnetic recording medium having superior corrosion resistance by exposing a ferromagnetic layer contg. a specified amt. of Cr to an atmosphere at a specified humidity and temp. CONSTITUTION:The amt. of Cr in a material forming a ferromagnetic layer is regulated to 3-30atom.%. In case of <3atom.% concn. of Cr, it is difficult to form a Cr-rich layer capable of exhibiting satisfactory corrosion resistance. In case of >30atom.% concn. of Cr, the saturation magnetization of the ferromagnetic layer is reduced and the reproduction output is reduced. The ferromagnetic layer is treated in an atmosphere having 70-98% relative humidity (RH). In case of <70% RH, a high temp. of >=300 deg.C is required so as to cause selective oxidation of Cr. In case of >98% RH, an ununiform Cr-rich layer is formed by dew condensation and the corrosion resistance is not considerably improved. The temp. of the atmosphere is regulated to >=50 deg.C so as to cause satisfactory selective oxidation.
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