US4690846A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Recording disk substrate members and process for producing same
Assignee: Proterial Ltd
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Filing: 1985-07-26
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Granted: 1987-09-01
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Expires: 2005-07-26
Abstract
Abstract A substrate member for recording disk characterized in that a glass coating film is provided on an alumina base ceramic material having micropores of no larger than 5 microns and a relative theoretical density of no less than 96%, said glass coating film having a surface roughness of no more than 80 angstroms, being substantially pore-free and strain-free on the surface, and having a thickness of 0.3 to 200 microns and a relative difference of no more than 10 -6 /deg in the coefficient of thermal expansion with respect to said base material.
Inventors
- 👤 Toshiaki Wada
- 👤 Yoshiaki Katsuyama
- 👤 Junichi Nakaoka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 18:27
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/73; G11B5/739; G11B5/73911; G11B5/73921; G11B5/73913; Y; Y10; Y10T; Y10T428/00; Y10T428/31
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
95 words
A substrate member for recording disk characterized in that a glass coating film is provided on an alumina base ceramic material having micropores of no larger than 5 microns and a relative theoretical density of no less than 96%, said glass coating film having a surface roughness of no more than 80 angstroms, being substantially pore-free and strain-free on the surface, and having a thickness of 0.3 to 200 microns and a relative difference of no more than 10 -6 /deg in the coefficient of thermal expansion with respect to said alumina base ceramic material.
Claim 2
Dependent Claim
95 words
A substrate member for recording disk characterized in that a glass coating film is provided on an alumina base ceramic material having micropores of no larger than 5 microns and a relative theoretical density of no less than 96%, said glass coating film having a surface roughness of no more than 80 angstroms, being substantially pore-free and strain-free on the surface, and having a thickness of 0.3 to 200 microns and a relative difference of no more than 10 -6 /deg in the coefficient of thermal expansion with respect to said alumina base ceramic material.
Claim 3
Dependent Claim
18 words
The substrate member as defined in claim 1, wherein the surface roughness is no more than 50 angstroms.
Claim 4
Dependent Claim
18 words
The substrate member as defined in claim 2, wherein the surface roughness is no more than 20 angstroms.
Claim 5
Dependent Claim
19 words
The substrate member as defined in claim 1, wherein the Bailby layer thickness is no more than 50 angstroms.
Claim 6
Dependent Claim
19 words
The substrate member as defined in claim 4, wherein the Bailby layer thickness is no more than 20 angstroms.
Claim 7
Dependent Claim
20 words
The substrate member as defined in claim 1, wherein the surface includes no pores having a diameter exceeding 0.2 micron.
Claim 8
Dependent Claim
20 words
The substrate member as defined in claim 1, wherein the surface includes no pores having a diameter exceeding 0.1 micron.
Claim 9
Dependent Claim
47 words
The substrate member as defined in claim 1, wherein said alumina base ceramic material is a sintered product of Al 2 O 3 , Al 2 O 3 --TiC--TiO 2 , Al 2 O 3 --TiO 2 or Al 2 O 3 --Fe 2 O 3 --TiC.
References Cited (Backward Citations)
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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) | 1990-08-31 | 1991-03-02 | 1991-09-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-08-31 | 1995-03-02 | 1995-09-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-08-31 | 1999-03-02 | 1999-09-01 | $7700.00 | Window Closed / Lapsed |