EP0435159A1
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Longitudinal magnetic recording medium
Assignee: Mitsubishi Chemical Corp
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Filing: 1990-12-19
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Granted: —
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Expires: 2010-12-19
Abstract
Abstract A longitudinal magnetic recording medium comprising a non-magnetic substrate having a texture with a central line average roughness Ra in a circumferential direction of at least 20 Å and a magnetic alloy layer comprising cobalt and chromium as the main components, formed on the substrate, wherein the magnetic alloy layer has (i) a feature that when the orientation degree of the hcp crystal structure is represented by the diffraction ray intensity of electron diffraction by transmission electron diffractiometry, the intensity ratio of the electron diffraction ring in the Co (002) plane between the circumferential direction and the radial direction of the substrate is at least 3, and (ii) a segregation structure having low chromium concentration regions surrounded by high chromium concentration regions, the diameters of the defined low chromium concentration regions being within a range of from 80 to 500 Å, and the number of the surrounded low chromium concentration regions being from 600 to 1,500 regions/µm².
Inventors
- 👤 Yukihiro Miyamoto
- 👤 Fumiaki Yokoyama
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 09:35
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/64; G11B5/65; G11B5/656; G11B5/73; G11B5/733; G11B5/7368; G11B5/7373; G11B5/739; G11B5/73911; G11B5/73913; G11B5/73917; G11B5/73919; G11B5/73921; G11B5/73923; G11B2005/0002; G11B2005/0026; G11B2005/0029; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10S428/922; Y10S428/9265; Y10S428/928; Y10T; Y10T428/00; Y10T428/12; Y10T428/12465; Y10T428/12493; Y10T428/12736; Y10T428/1275; Y10T428/12771; Y10T428/12806; Y10T428/12826; Y10T428/12847; Y10T428/12854; Y10T428/12861; Y10T428/12944; Y10T428/26; Y10T428/263; Y10T428/264; Y10T428/265; Y10T428/31
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
157 words
A longitudinal magnetic recording medium comprising a non-magnetic substrate having a texture with a central line average roughness Ra in a circumferential direction of at least 20 Å and a magnetic alloy layer comprising cobalt and chromium as the main components, formed on the substrate, wherein the magnetic alloy layer has (i) a feature that when the orientation degree of the hcp crystal structure is represented by the diffraction ray intensity of electron diffraction by transmission electron diffractiometry, the intensity ratio of the electron diffraction ring in the Co (002) plane between the circumferential direction and the radial direction of the substrate is at least 3, and (ii) a segregation structure having low chromium concentration regions surrounded by high chromium concentration regions, the diameters of the surrounded low chromium concentration regions being within a range of from 80 to 500 Å, and the number of the surrounded low chromium concentration regions being from 600 to 1,500 regions/µm².
Claim 2
Dependent Claim
33 words
The longitudinal magnetic recording medium according to Claim 1, wherein the non-magnetic substrate has a texture with a central line average roughness Ra in a circumferential direction of from 30 to 300 Å.
Claim 3
Dependent Claim
54 words
The longitudinal magnetic recording medium according to Claim 1, wherein the orientation degree of the hcp crystal structure of the magnetic alloy layer is such that the intensity ratio of the electron diffraction ring in the Co (002) plane between the circumferential direction and the radial direction of the substrate is at least 5.
Claim 4
Dependent Claim
31 words
The longitudinal magnetic recording medium according to Claim 1, wherein at least 95% of the surrounded low chromium concentration regions have diameters within the range of from 80 to 500 Å.
Claim 5
Dependent Claim
25 words
The longitudinal magnetic recording medium according to Claim 1, wherein the number of the surrounded low chromium concentration regions is from 800 to 1,500 regions/µm².
Claim 6
Dependent Claim
28 words
The longitudinal magnetic recording medium according to Claim 1, wherein the chromium concentration in the magnetic alloy layer is from 6 to 25 atomic % relative to cobalt.
Claim 7
Dependent Claim
33 words
The longitudinal magnetic recording medium according to Claim 1, wherein the magnetic alloy layer contains additive elements selected from the group consisting of Ta, Nb, Pt, Pd, Ni, Zr, W, Mo and Hf.
Claim 8
Dependent Claim
49 words
The longitudinal magnetic recording medium according to Claim 1, wherein the magnetic alloy layer is provided on the non-magnetic substrate having a texture with a non-magnetic primer layer having a thickness of from 500 to 2,000 Å interposed therebetween, and the non-magnetic primer layer is a chromium primer layer.
Claim 9
Dependent Claim
29 words
The longitudinal magnetic recording medium according to Claim 1, wherein the non-magnetic substrate having a texture is an aluminum alloy plate having a Ni-P layer formed by electroless plating.
Claim 10
Dependent Claim
36 words
The longitudinal magnetic recording medium according to Claim 1, wherein the non-magnetic substrate having a texture is selected from the group consisting of a metal substrate, a glass substrate, a ceramic substrate and a resin substrate.
Claim 11
Dependent Claim
23 words
The longitudinal magnetic recording medium according to Claim 1, wherein the magnetic alloy layer has a thickness of from 300 to 1,500 Å.
Claim 12
Dependent Claim
24 words
The in-plane magnetic recording medium according to Claim 1, wherein a protective layer and/or a lubricating layer is formed on the magnetic alloy layer.
Claim 13
Dependent Claim
206 words
An longitudinal magnetic recording medium comprising a non-magnetic substrate having a texture with a central line average roughness Ra in a circumferential direction of at least 20 Å provided on an aluminum alloy plate having a Ni-P layer formed by electroless plating, and a magnetic alloy layer comprising cobalt and chromium as the main components, formed on the substrate with a non-magnetic primer layer having a thickness of from 500 to 2,000 Å interposed therebetween, wherein the magnetic alloy layer has (i) a feature that when the orientation degree of the hcp crystal structure is represented by the diffraction ray intensity of electron diffraction by transmission electron diffractiometry, the intensity ratio of the electron diffraction ring in the Co (002) plane between the circumferential direction and the radial direction of the substrate is at least 3, and (ii) a segregation structure having low chromium concentration regions surrounded by high chromium concentration regions, the diameters of the surrounded low chromium concentration regions being within a range of from 80 to 500 Å, and the number of the surrounded low chromium concentration regions being from 600 to 1,500 regions/µm², and a protecting layer is formed on the magnetic alloy layer, and a lubricating layer is formed further thereon.
References Cited (Backward Citations)
GB2071145A
Cited
DE3629582A1
Cited
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