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AssigneeShowa Denko K.K.
InventorsAkira Sakawaki, Masato Kokubu, Hiroshi Sakai
Estimating the term…
A magnetic recording medium which exhibits excellent magnetic characteristics and which can be easily produced is disclosed. A magnetic recording medium containing a non-metallic substrate 1, a non-magnetic undercoat film 3, a cobalt alloy hexagonal closed packed (hcp) (110) textured magnetic film 4, and a protective film 5 formed on the substrate. An orientation-determining film 2, which determines the crystal orientation of an undercoat film provided directly thereon to cause the texture of the undercoat film to be (200), is formed between the substrate 1 and the undercoat film 3. The orientation-determining film 2 has a crystal structure such that columnar fine crystal grains 2a are inclined in a radial direction of the substrate 1, and the ratio of a coercive force in a circumferential direction of the medium (Hcc) to a coercive force in a radial direction of the medium (Hcr); i.e., Hcc/Hcr, is more than 1.
A magnetic recording medium comprising (1) a non-metallic substrate, (2) an orientation-determining film which determines the crystal orientation of an undercoat film provided directly thereon to cause the texture of the undercoat film to be (200), (3) a non-magnetic undercoat film, (4) a cobalt alloy hexagonal closed packed (hcp) (110) textured magnetic film, and (5) a protective film in order;
A magnetic recording medium comprising (1) a non-metallic substrate, (2) an orientation-determining film which determines the crystal orientation of an undercoat film provided directly thereon to cause the texture of the undercoat film to be (200), (3) a non-magnetic undercoat film, (4) a magnetic film, and (5) a protective film in order;
Dependencies are inferred from the claim text.
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From the US filing history. Foreign family members aren’t listed.
Processes or apparatus specially adapted for manufacturing record carriers: manufacturing base layers
Two or more non-magnetic underlayers, e.g. seed layers or barrier layers: physical structure of underlayer, e.g. texture
Stock material or miscellaneous articles: magnetic feature
All metal or with adjacent metals: having magnetic properties, or preformed fiber orientation coordinate with shape
Term ended 11 Oct 2021 (estimated)
The present invention relates to a magnetic recording medium used in an apparatus such as a magnetic disk apparatus; a process and an apparatus for producing the magnetic recording medium; and a magnetic recording and reproducing apparatus incorporating the magnetic recording medium.
Conventionally, a metallic substrate formed from, for example, an aluminum alloy is widely used as a substrate for producing a magnetic recording medium. Usually, such a metallic substrate undergoes texturing, and is used for producing a magnetic recording medium.
Texturing is a process for forming irregularities on a substrate along a predetermined direction (usually in a circumferential direction) of the substrate. When the surface of a substrate undergoes texturing, the crystal orientation of an undercoat film and a magnetic film, which are formed on the substrate, is enhanced, and the magnetic film exhibits magnetic anisotropy, and thus magnetic characteristics, such as thermal stability and resolution, of a magnetic recording medium can be enhanced.
FIG. 1(a) is a partial cross-sectional view showing an embodiment of the magnetic recording medium of the present invention.
FIG. 1(b) is an enlarged view showing an essential portion of the magnetic recording medium shown in FIG. 1(a), which is prepared from the transmission electron microscope (TEM) photograph of the cross section of the medium.
FIG. 2 is a schematic representation showing an embodiment of the production apparatus for the magnetic recording medium of the present invention.
1. Non-metallic substrate
1a. Non-metallic substrate surface (deposition surface)
2. Orientation-determining film