MAGNETIC RECORDING MEDIUM

摘要

PURPOSE:To improve magnetic characteristics and corrosion resistance by consisting a magnetic layer of a Co-Ni alloy contg. 2.5-12at% Sm and consisting of a nonmagnetic metallic underlying layer of W. CONSTITUTION:A nonmagnetic substrate 2 is formed by using a disk-shaped aluminum plate finished to <=20mum surface in both circumferential and radial directions, forming an electroless plating film of the Ni-P alloy thereon to about 30mum thickness and finishing the plating film to a specular surface up to 0.02mum average surface roughness and 15mum thickness. The nonmagnetic metallic underlying layer 3 is then formed on the substrate 2 by sputtering W. The magnetic layer 4 is formed by sputtering onto the W underlying layer 3 to about 500Angstrom thickness within the same sputtering vessel immediately after the formation of the layer 3. The Co-30at%Ni alloy contg. 10at% Sm is used as the magnetic layer to determine the thickness of the W film. The time for sputtering is thus shortened by using the thin W film for the nonmagnetic metallic underlying layer nd the magnetic layer made of the compsn. exhibiting the good magnetic characteristics is obtd. Excellent corrosion resistance is obtd. as well.