Patent US4808463A successfully refreshed from Google Patents.
US4808463A
Expired / Lapsed
US
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Substrate for magnetic disks
Assignee: Kyocera Corp
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Filing: 1986-07-22
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Granted: 1989-02-28
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Expires: 2006-07-22
Abstract
Abstract A substrate for magnetic disk comprises a ceramic support having a glaze layer formed on the surface which is to be coated with a magnetic recording material. The ceramic support may be made of alumina, and the glaze layer is made of a material having substantially the same expansion coefficient as that of the ceramic support. That material has a relatively high melting point.
Inventors
- 👤 Okabayashi Yoshikatsu
- 👤 Matsuda Osamu
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 14:40
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/01; C04B35/10; C04B35/111; G; G11; G11B; G11B5/00; G11B5/62; G11B5/73; G11B5/739; G11B5/73911; G11B5/73913; G11B5/73921; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/24; Y10T428/24942; Y10T428/2495; Y10T428/24967; Y10T428/24975; Y10T428/26; Y10T428/263; Y10T428/264; Y10T428/265
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
94 words
A substrate for magnetic disks comprising a support including at least a polycrystalline ceramic material having a crystalline particulate diameter of no greater than 100 μm and a glaze layer formed on at least one surface of said support, said glaze layer being coated with a magnetic recording material, wherein said support and said glaze layer have substantially the same thermal expansion coefficient and said support and said glaze layer can withstand temperatures up to 500° C. with substantially no dimensional instability wherein the glaze layer has a thickness of not greater than 150μm.
Claim 2
Dependent Claim
94 words
A substrate for magnetic disks comprising a support including at least a polycrystalline ceramic material having a crystalline particulate diameter of no greater than 100 μm and a glaze layer formed on at least one surface of said support, said glaze layer being coated with a magnetic recording material, wherein said support and said glaze layer have substantially the same thermal expansion coefficient and said support and said glaze layer can withstand temperatures up to 500° C. with substantially no dimensional instability wherein the glaze layer has a thickness of not greater than 150μm.
Claim 3
Dependent Claim
23 words
The substrate according to claim 1, wherein the thermal expansion coefficient of said glaze layer is in the range of 55-75×10 -7 /°C.
Claim 4
Dependent Claim
23 words
The substrate according to claim 1, wherein the thermal expansion coefficient of said glaze layer is in the range of 60-70×10 -7 /°C.
Claim 5
Dependent Claim
21 words
The substrate according to claim 1, wherein the thermal coefficient of said support is in the range of 60-80×10 -7 /°C.
Claim 6
Dependent Claim
25 words
The substrate according to claim 1, wherein a difference in thermal coefficient between said support and said glaze layer is 10×10 -7 /°C. or less.
Claim 7
Dependent Claim
25 words
The substrate according to claim 1, wherein a difference in thermal coefficient between said support and said glaze layer is 5×10 -7 /°C. or less.
Claim 8
Dependent Claim
22 words
The substrate according to claim 1, wherein said support is made of alumina base material containing 90% by weight or more alumina.
Claim 9
Dependent Claim
39 words
The substrate according to claim 1, wherein said glaze layer is made of 50% SiO 2 , 25% BaO, and 12% CaO by weight, small amounts of B 2 O, Al 2 O 3 and ZnO and the balance.
Claim 10
Dependent Claim
16 words
The substrate according to claim 1, wherein said glaze layer has a relatively high melting point.
Claim 11
Dependent Claim
16 words
The substrate according to claim 9, wherein said melting point is not lower than 600° C.
Claim 12
Dependent Claim
17 words
The substrate according to claim 1, wherein said glaze layer has a softening temperature of 850° C.
Claim 13
Dependent Claim
95 words
A substrate for magnetic disk comprising a support including at least a polycrystalline ceramic material having a crystalline particulate diameter of no greater than 100 μm and a glaze layer formed on at least one surface of said support, said glaze layer being coated with a magnetic recording material, wherein a thermal coefficient of said support is greater than that of said glaze layer and said support and said glaze layer can withstand temperatures up to 500° C. with substantially no dimensional instability wherein the glaze layer has a thickness of not greater than 150μm.
Claim 14
Dependent Claim
95 words
A substrate for magnetic disk comprising a support including at least a polycrystalline ceramic material having a crystalline particulate diameter of no greater than 100 μm and a glaze layer formed on at least one surface of said support, said glaze layer being coated with a magnetic recording material, wherein a thermal coefficient of said support is greater than that of said glaze layer and said support and said glaze layer can withstand temperatures up to 500° C. with substantially no dimensional instability wherein the glaze layer has a thickness of not greater than 150μm.
Claim 15
Dependent Claim
23 words
The substrate according to claim 12, wherein the thermal expansion coefficient of said glaze layer is in the range of 55-75×10 -7 /°C.
Claim 16
Dependent Claim
23 words
The substrate according to claim 12, wherein the thermal expansion coefficient of said glaze layer is in the range of 60-70×10 -7 /°C.
Claim 17
Dependent Claim
21 words
The substrate according to claim 12, wherein the thermal coefficient of said support is in the range of 60-80×10 -7 /°C.
Claim 18
Dependent Claim
22 words
The substrate according to claim 12, wherein said support is made of alumina base material containing 90% by weight or more alumina.
Claim 19
Dependent Claim
39 words
The substrate according to claim 12, wherein said glaze layer is made of 50% SiO 2 , 25% BaO, and 12% CaO by weight, small amounts of B 2 O, Al 2 O 3 and ZnO and the balance.
Claim 20
Dependent Claim
16 words
The substrate according to claim 12, wherein said glaze layer as a relatively high melting point.
Claim 21
Dependent Claim
16 words
The substrate according to claim 18, wherein said melting point is not lower than 600° C.
Claim 22
Dependent Claim
17 words
The substrate according to claim 12, wherein said glaze layer has a softening temperature of 850° C.
Claim 23
Dependent Claim
80 words
A substrate for magnetic discs comprising a support including at least a polycrystalline ceramic material having a crystalline particulate diameter of no greater than 100 μm and a glaze layer formed on at least one surface of said support, wherein said glaze layer has a relatively high melting point and said support and said glaze layer can withstand temperatures up to 500° C. with substantially no dimensional instability wherein the glaze layer has a thickness of not greater than 150μm.
Claim 24
Dependent Claim
80 words
A substrate for magnetic discs comprising a support including at least a polycrystalline ceramic material having a crystalline particulate diameter of no greater than 100 μm and a glaze layer formed on at least one surface of said support, wherein said glaze layer has a relatively high melting point and said support and said glaze layer can withstand temperatures up to 500° C. with substantially no dimensional instability wherein the glaze layer has a thickness of not greater than 150μm.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-02-28 | 1992-08-29 | 1993-02-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-02-28 | 1996-08-29 | 1997-02-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-02-28 | 2000-08-29 | 2001-02-28 | $7700.00 | Window Closed / Lapsed |