| 摘要 |
PURPOSE:To provide excellent corrosion resistance and a high recording density characteristic by covering a thin metallic film medium consisting of a cobalt alloy contg. titanium and platinum or a cobalt alloy contg. molybdenum and platinum on an alloy disc and covering a protective film thereon. CONSTITUTION:A nickel-phosphorus alloy is plated on a base plate 1 and the surface of the ground body 2 is finished by mechanical polishing to a specular surface having <=0.03mum max. surface roughness. A thin metallic film medium consisting of a cobalt alloy contg. molybdenum or titanium and platinum is coated on the specularly polished surface of the body 2 by a high-frequency sputtering method as a magnetic medium 3. A protective film 4 as represented by SiO2 is further coated on the medium 3 by a high frequency sputtering method. The thin metallic film medium exhibits the hysteresis characteristic within a range of 500-1,200 oe (oersted) coercive force (Hv), <=1,200 G (gauss) saturation magnetic flux density (Bs), 0.7-0.9 squareness ratio (Br/Bs) and 0.7-0.9 squareness ratio of coercive force (S). |
