Patent US4657816A successfully refreshed from Google Patents.
US4657816A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ferromagnetic recording materials
Assignee: Memorex Telex NV
•
Filing: 1982-04-19
•
Granted: 1987-04-14
•
Expires: 2002-04-19
Abstract
Abstract Low performance ferromagnetic oxides are taught to be convertible into high performance ferromagnetic oxides with vastly improved coercivity by suspending ferromagnetic oxide particles in aqueous media, forming a layer of the first metal on the surfaces of the particles, forming a layer of second metal on the surfaces of the first metal and lastly, forming a layer of third metal on the surfaces of the second metal. The first and third metals can be the same in preferably transition metals such as cobalt. The second metal must be different than the first and third metals such as, for example, iron.
Inventors
- 👤 Mohammed Siddiq
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 18:40
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/706; G11B5/70626; G11B5/70642; G11B5/70647; G11B5/712; H; H01; H01F; H01F1/00; H01F1/01; H01F1/03; H01F1/032; H01F1/10; H01F1/11; H01F1/112; A; A63; A63B; A63B2225/00; A63B2225/50; A63B43/00; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/29; Y10T428/2982; Y10T428/2991
Claims Analysis
Total Claims: 42
Claim 1
Independent Claim
120 words
A method of converting low performance ferromagnetic oxides into high performance ferromagnetic oxides adapted for a prescribed magnetic recording media coating comprising: a. Suspending low performance ferromagnetic oxide particles in an aqueous medium; b. Adding a first magnetic metal moiety and treating to form a layer of a first metal compound on the surfaces of the particles; c. Adding a second magnetic metal moiety and treating to form a layer of a second metal compound on the surfaces of the first metal; and d. Adding a third magnetic metal moiety and treating to form a layer of a third metal compound on the surfaces of the second metal compound; and e. Preparing the resultant particles for inclusion in said coating.
Claim 2
Independent Claim
120 words
A method of converting low performance ferromagnetic oxides into high performance ferromagnetic oxides adapted for a prescribed magnetic recording media coating comprising: a. Suspending low performance ferromagnetic oxide particles in an aqueous medium; b. Adding a first magnetic metal moiety and treating to form a layer of a first metal compound on the surfaces of the particles; c. Adding a second magnetic metal moiety and treating to form a layer of a second metal compound on the surfaces of the first metal; and d. Adding a third magnetic metal moiety and treating to form a layer of a third metal compound on the surfaces of the second metal compound; and e. Preparing the resultant particles for inclusion in said coating.
Claim 3
Dependent Claim
41 words
The method of claim 1 wherein the first metal compound and third metal compound are comprised of the same magnetic metal, executing all these forming steps as part of a single sequence in a single vessel and using wet chemistry methods.
Claim 4
Dependent Claim
27 words
The method of claim 2 wherein said first metal and third metal are selected from the group consisting of cobalt, iron, manganese, nickel, zinc, and mixtures thereof.
Claim 5
Dependent Claim
20 words
The method of claim 3 wherein said first metal and third metal are cobalt and said second metal is iron.
Claim 6
Dependent Claim
20 words
The method of claim 3 wherein said first metal and third metal are iron and said second metal is cobalt.
Claim 7
Dependent Claim
22 words
The method of claim 1 wherein additional alternating layers of metal compounds are formed on the surfaces of said third metal compound.
Claim 8
Dependent Claim
32 words
The method of claim 6 wherein the additional alternating layers of metal compounds are comprised of a metal selected from the group consisting of coablt, iron, manganese, nickel, zinc and mixtures thereof.
Claim 9
Dependent Claim
55 words
The method of claim 1 wherein said first, second and third metal compound layers are formed by providing individual solutions of metal salts of each metal compound separately and adding a sufficient quantity of a base to cause metal ion adsorption reactions to take place on each surface to which the metal compounds are applied.
Claim 10
Dependent Claim
29 words
The method of claim 8 wherein the metal ions in each solution are added in each instance in an amount to saturate the surfaces to which they are applied.
Claim 11
Dependent Claim
32 words
The method of claim 1 wherein said low performance ferromagnetic oxides are selected from the group consisting of γ-Fe 2 O 3 , Fe 3 O 4 , and intermediate oxides thereof.
Claim 12
Dependent Claim
28 words
The method of claim 8 wherein the first and third metal compound layers comprise cobalt ions derived from CoSO 4 .7H 2 O and other divalent cobalt salts.
Claim 13
Dependent Claim
26 words
The method of claim 11 wherein the second metal compound layer comprises iron ions derived from FeSO 4 .7H 2 O and other divalent ion salts.
Claim 14
Dependent Claim
10 words
The method of claim 8 wherein the base comprises NaOH.
Claim 15
Dependent Claim
34 words
A high performance ferromagnetic oxide particle comprising a ferromagnetic oxide core, and coatings of three metal compounds thereon wherein the second metal compound coating is dissimilar to the first and third metal compound coatings.
Claim 16
Dependent Claim
34 words
A high performance ferromagnetic oxide particle comprising a ferromagnetic oxide core, and coatings of three metal compounds thereon wherein the second metal compound coating is dissimilar to the first and third metal compound coatings.
Claim 17
Dependent Claim
20 words
The high performance ferromagnetic oxide particle of claim 14 wherein said first and third metal compound coatings are the same.
Claim 18
Dependent Claim
31 words
The high performance ferromagnetic oxide particle of claim 15 wherein the first metal and third metal are selected from the group consisting of cobalt, iron, manganese, nickel, zinc and mixtures thereof.
Claim 19
Dependent Claim
27 words
The high performance ferromagnetic oxide particle of claim 16 wherein said first metal ion and third metal ion comprise cobalt and said second metal ion comprises iron.
Claim 20
Dependent Claim
27 words
The high performance ferromagnetic oxide particle of claim 16 wherein said first metal ion and third metal ion comprise iron and said second metal ion comprise cobalt.
Claim 21
Dependent Claim
26 words
The high performance ferromagnetic oxide particle of claim 14 further comprising additional alternating layers of metal compounds formed on the surface of said third metal compound.
Claim 22
Dependent Claim
36 words
The high performance ferromagnetic oxide particle of claim 19 wherein the said alternating layers of metal compounds are comprised of metal ions selected from the group consisting of cobalt, iron, manganese, nickel, zinc and mixtures thereof.
Claim 23
Dependent Claim
32 words
A high performance ferromagnetic oxide particle comprising a ferromagnetic oxide core, and coatings of two metal compounds thereon, wherein the second metal compound coating is dissimilar to the first metal compound coating.
Claim 24
Dependent Claim
32 words
A high performance ferromagnetic oxide particle comprising a ferromagnetic oxide core, and coatings of two metal compounds thereon, wherein the second metal compound coating is dissimilar to the first metal compound coating.
Claim 25
Dependent Claim
31 words
The high performance ferromagnetic oxide particle of claim 21 wherein said first and second metal ions are selected from the group consisting of cobalt, iron, magnanese, nickel, zinc and mixtures thereof.
Claim 26
Dependent Claim
38 words
The high performance ferromagnetic oxide particle of claim 22 wherein the coercivity of the particle is further increased by subjecting the particle to heat treatment after the metal compound coatings have been applied to the ferromagnetic oxide core.
Claim 27
Dependent Claim
19 words
In a magnetic recording member the improvement comprising the high performance ferromagnetic oxide particles of claims 14 or 21.
Claim 28
Independent Claim
119 words
A method of converting low performance ferromagnetic oxides into high performance ferromagnetic oxides without need for post-heating and without need to resort to separate reactive vessels or to other than wet chemistry methods, this method comprising: a. Suspending low performance ferromagnetic oxide particles in an aqueous media; b. Forming a layer of a first metallic constituent on the surfaces of the particles; and forming at least one other pair of layers thereon, each such pair formed by; c. Forming a layer of a second metal constituent on the surfaces of the first constituents; and d. Forming a layer of a third metal constituent on the surfaces of the second metal constituent; said second constituent being different from the others.
Claim 29
Independent Claim
119 words
A method of converting low performance ferromagnetic oxides into high performance ferromagnetic oxides without need for post-heating and without need to resort to separate reactive vessels or to other than wet chemistry methods, this method comprising: a. Suspending low performance ferromagnetic oxide particles in an aqueous media; b. Forming a layer of a first metallic constituent on the surfaces of the particles; and forming at least one other pair of layers thereon, each such pair formed by; c. Forming a layer of a second metal constituent on the surfaces of the first constituents; and d. Forming a layer of a third metal constituent on the surfaces of the second metal constituent; said second constituent being different from the others.
Claim 30
Dependent Claim
19 words
The method of claim 25 wherein the first and third metal constituents are formed of the same metal ions.
Claim 31
Dependent Claim
30 words
The method of claim 26 wherein the metal constituents of the first and third layers are selected from the group consisting of cobalt, iron, manganese, nickel, zinc, and mixtures thereof.
Claim 32
Dependent Claim
24 words
The method of claim 27 wherein the metal of the first and third metal layers is cobalt, while the second metal layer comprises iron.
Claim 33
Dependent Claim
23 words
The method of claim 27 wherein the first and third metal layers are comprised of iron and the second metal layer of cobalt.
Claim 34
Dependent Claim
22 words
The method of claim 25 wherein additional alternating layers of dissimilar metals are formed on the surfaces of said third metal layer.
Claim 35
Dependent Claim
46 words
A high performance ferromagnetic particle comprising a ferromagnetic oxide core, and at least three coatings of metal constituents thereon wherein the metallic composition of the second and all other successive even-number layers is dissimilar from the composition of the first and all other successive odd-numbered layers.
Claim 36
Dependent Claim
46 words
A high performance ferromagnetic particle comprising a ferromagnetic oxide core, and at least three coatings of metal constituents thereon wherein the metallic composition of the second and all other successive even-number layers is dissimilar from the composition of the first and all other successive odd-numbered layers.
Claim 37
Dependent Claim
20 words
The high performance ferromagnetic oxide particle of claim 31 wherein the odd-number layers are comprised of the same metallic composition.
Claim 38
Dependent Claim
33 words
The high performance ferromagnetic oxide particle of claim 32 wherein the odd-number layers are formed from identical metal ions selected from the group consisting of cobalt, iron, manganese, nickel, zinc and mixtures thereof.
Claim 39
Dependent Claim
21 words
The high performance ferromagnetic oxide particle of claim 33 wherein the odd-number layers comprise cobalt and the even-number layers comprise iron.
Claim 40
Dependent Claim
21 words
The high performance ferromagnetic oxide particle of claim 32 wherein the odd-number layers comprise iron and the even-number layers comprise cobalt.
Claim 41
Dependent Claim
31 words
The high performance ferromagnetic oxide particle of claim 31 further comprising at least one additional pair of alternating layers of different metallic composition formed on the surface of the third layer.
Claim 42
Dependent Claim
35 words
The high performance ferromagnetic oxide particle of claim 36 wherein the metal ions selected to form the different alternating layers are selected from the group consisting of cobalt, iron, manganese, nickel, zinc and mixtures thereof.
References Cited (Backward Citations)
US3770500A
Cited
US3958068A
Cited
US4069367A
Cited
US3977985A
Cited
US4064292A
Cited
US4010310A
Cited
US4200680A
Cited
US4067755A
Cited
US4066565A
Cited
US4066564A
Cited
US4125474A
Cited
US4188302A
Cited
US4267207A
Cited
US4224175A
Cited
US4226909A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-04-13 | 1990-10-13 | 1991-04-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-04-13 | 1994-10-13 | 1995-04-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-04-13 | 1998-10-13 | 1999-04-14 | $7700.00 | Window Closed / Lapsed |