| 摘要 |
PROBLEM TO BE SOLVED: To form the magnetic layer surface, which provides a good head wear resistance, a superior head cleaning characteristic and durability by providing at least one layer or more of the magnetic layer on the surface of a nonmagnetic supporting body and making the layer to include Al2 O3 having two kinds or more of different crystal systems as abrasives. SOLUTION: Al2 O3 having two kinds or more of different crystal systems is used as the abrasives used for the magnetic coating material to form a magnetic layer. In general,α,β,γ,θandκtypes are available for the crystal systems. However, it is desirable to use the combination of theαandβtypes. Ifαandβtype Al2 O3 are included as the abrasives, it is desirable to make the X-ray diffraction strength ratio of aβ-Al2 O3 (107) surface against the X-ray diffraction strength diffracted from anα-Al2 O3 (113) surface to be 0.2 to 2%. Moreover, it is desirable, from the durability improvement point of view, that the average particle diameter of Al2 O3 , as abrasives, to be 0.02 to 1μm. As a matter of fact, it is most desirable to set the diameter within the range of 0.05 to 0.7μm.
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