Patent US4840844A successfully refreshed from Google Patents.
US4840844A
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Magnetic recording medium
Assignee: HGST Japan Ltd
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Filing: 1987-06-02
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Granted: 1989-06-20
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Expires: 2007-06-02
Abstract
Abstract A magnetic recording medium which comprises a non-magnetic substrate, a magnetic film formed on the substrate and a protective film provided on the magnetic film, the protective film being composed of at least two groups of element, the element in one group being at least one of B and C having a smaller atomic size, and a concentration of the element increasing from the interface side of the protective film with the magnetic film toward the opposite face side throughout the protective film has an improved durability against a magnetic head.
Inventors
- 👤 Masaaki Futamoto
- 👤 Yukio Honda
- 👤 Shinichiro Saito
- 👤 Takashi Nishimura
- 👤 Kazuetsu Yoshida
- 👤 Toyoji Okuwaki
- 👤 Hitoshi Iwata
- 👤 Hiroyuki Suzuki
- 👤 Kazushige Imagawa
- 👤 Hideo Daimon
- 👤 Osamu Kitakami
- 👤 Hideo Fujiwara
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 21:39
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/72; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/26; Y10T428/263; Y10T428/264; Y10T428/265; Y10T428/30; Y10T428/31504; Y10T428/31678
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
84 words
A magnetic recording medium which comprises a non-magnetic substrate, a magnetic film formed on the substrate and a protective film having a thickness of 50 to 2,000 Å provided on the magnetic film, the protective film containing at least one selected element selected from the group consisting of B and C as a constituent element, and the concentration of the selected element increasing throughout the protective film from the interface side with the magnetic film toward the opposite face side in a continuous manner.
Claim 2
Dependent Claim
84 words
A magnetic recording medium which comprises a non-magnetic substrate, a magnetic film formed on the substrate and a protective film having a thickness of 50 to 2,000 Å provided on the magnetic film, the protective film containing at least one selected element selected from the group consisting of B and C as a constituent element, and the concentration of the selected element increasing throughout the protective film from the interface side with the magnetic film toward the opposite face side in a continuous manner.
Claim 3
Dependent Claim
52 words
A magnetic recording medium according to claim 1, wherein at least one additional element selected from the group consisting of Ti, Zr, Hf, V, Nb, W, Ta, Al and Si is contained in the protective film beside the at least one selected element selected from the group consisting of B and C.
Claim 4
Dependent Claim
44 words
A magnetic recording medium according to claim 1, wherein a difference in the protective film between the concentration of the selected element on the interface side with the magnetic film and that on the face side of the protective film is at least 5%.
Claim 5
Dependent Claim
105 words
A recording magnetic medium which comprises a non-magnetic substrate, a magnetic film formed on the substrate and a protective film provided on the magnetic film, the protective film being in a multi-layer structure composed of a plurality of carbon layers and a plurality of metal layers, alternately laid one upon another, the outermost layer of the protective film in contact with the magnetic film being a metal layer composed of at least one element selected from the group consisting of Si, Zr, W, V, B, Cr, Ti and Ta, and the outermost layer on the face side of the protective film being a carbon layer.
Claim 6
Dependent Claim
105 words
A recording magnetic medium which comprises a non-magnetic substrate, a magnetic film formed on the substrate and a protective film provided on the magnetic film, the protective film being in a multi-layer structure composed of a plurality of carbon layers and a plurality of metal layers, alternately laid one upon another, the outermost layer of the protective film in contact with the magnetic film being a metal layer composed of at least one element selected from the group consisting of Si, Zr, W, V, B, Cr, Ti and Ta, and the outermost layer on the face side of the protective film being a carbon layer.
Claim 7
Dependent Claim
50 words
A recording magnetic medium according to claim 4, wherein said outermost layer on the face side of the protective film has a thickness of 0.5 to 10 nm and said outermost layer of the protective film in contact with the magnetic frilm has a thickness of 0.5 to 30 nm.
Claim 8
Dependent Claim
29 words
A recording magnetic medium according to claim 4, wherein said multi-layer structure has been heated in a vacuum to promote interfusion between said carbon layers and said metal layers.
Claim 9
Dependent Claim
32 words
A recording magnetic medium according to claim, 6, wherein each of said plurality of metal layers and each of said plurality of carbon layers has a thickness of 0.5 to 2.0 nm.
Claim 10
Dependent Claim
20 words
A magnetic recording medium according to claim 9 wherein said protective film has a thickness of 100 to 300 Å.
Claim 11
Dependent Claim
107 words
A magnetic recording medium which comprises a non-magnetic substrate, a magnetic film formed on the substrate and a protective film having a thickness of 50 to 2,000Å provided on the magnetic film, the protective film containing at least one selected element selected from the group consisting of B and C as a constituent element and at least one additional element having an atomic size equal to or larger than those of the constituent elements of said magnetic film, and the concentration of the selected element increasing throughout the protective film from the interface side with the magnetic film toward the opposite face side in a continuous manner.
Claim 12
Dependent Claim
107 words
A magnetic recording medium which comprises a non-magnetic substrate, a magnetic film formed on the substrate and a protective film having a thickness of 50 to 2,000Å provided on the magnetic film, the protective film containing at least one selected element selected from the group consisting of B and C as a constituent element and at least one additional element having an atomic size equal to or larger than those of the constituent elements of said magnetic film, and the concentration of the selected element increasing throughout the protective film from the interface side with the magnetic film toward the opposite face side in a continuous manner.
Claim 13
Dependent Claim
20 words
A magnetic recording medium according to claim 9, wherein said protective film has a thickness of 100 to 300 Å.
Claim 14
Dependent Claim
33 words
A magnetic recording medium according to claim 9, wherein said additional element is at least one member selected from the group consisting of Ti, Zr, Hf, V, Nb, W, Ta, Al and Si.
Claim 15
Dependent Claim
44 words
A magnetic recording medium according to claim 9, wherein a difference in the protective film between the concentration of the selected element on the interface side with the magnetic film and that on the face side of the protective film is at least 5%.
Claim 16
Dependent Claim
78 words
A magnetic recording medium which comprises a non-magnetic substrate, a magnetic film formed on the substrate and a protective film having a thickness of 50 to 2,000 Å provided on the magnetic film, the protective film being composed of B, C and Si, and a concentration in total of B and C increasing from the interface side of the protective film with the magnetic film toward the opposite face side throughout the protective film in a continuous manner.
Claim 17
Dependent Claim
78 words
A magnetic recording medium which comprises a non-magnetic substrate, a magnetic film formed on the substrate and a protective film having a thickness of 50 to 2,000 Å provided on the magnetic film, the protective film being composed of B, C and Si, and a concentration in total of B and C increasing from the interface side of the protective film with the magnetic film toward the opposite face side throughout the protective film in a continuous manner.
Claim 18
Dependent Claim
46 words
A magnetic recording medium according to claim 13, wherein a difference in the protective film between the concentration in total of B and C on the interface side with the magnetic film and that on the face side of the protective film is at least 5%.
Claim 19
Dependent Claim
20 words
A magnetic recording medium according to claim 13, wherein said protective film has a thickness of 100 to 300 Å.
Claim 20
Dependent Claim
69 words
A magnetic recording medium which comprises a non-magnetic substrate, a magnetic film formed on the substrate and a protective film having a thickness of 50 to 2,000 Å provided on the magnetic film, the protective film being composed of B and C, and a concentration of C increasing from the interface side of the protective film toward the opposite face side throughout the protective film in a continuous manner.
Claim 21
Dependent Claim
69 words
A magnetic recording medium which comprises a non-magnetic substrate, a magnetic film formed on the substrate and a protective film having a thickness of 50 to 2,000 Å provided on the magnetic film, the protective film being composed of B and C, and a concentration of C increasing from the interface side of the protective film toward the opposite face side throughout the protective film in a continuous manner.
Claim 22
Dependent Claim
45 words
A magnetic recording medium according to claim 16, wherein a difference in the protective film between the concentration in total of B and C on the interface side with the magnetic film and that on the face of the protective film is at least 5%.
Claim 23
Dependent Claim
20 words
A magnetic recording medium according to claim 16, wherein said protective film has a thickness of 100 to 300 Å.
References Cited (Backward Citations)
US32464A
Cited
USRE32464E
Cited
US4411963A
Cited
US4503125A
Cited
US4664976A
Cited
US4647494A
Cited
JPH11331A
Cited
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