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Patent US4253886A successfully refreshed from Google Patents.
US4253886A
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Corrosion resistant ferromagnetic metal powders and method of preparing the same
Assignee: Fujifilm Holdings Corp
•
Filing: 1977-08-08
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Granted: 1981-03-03
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Expires: 1997-08-08
Abstract
Abstract Corrosion resistant ferromagnetic metal powders in which a volatile corrosion inhibitor is adsorbed on at least a part of the surface of ferromagnetic metal powders having an average particle size of 1000 A or less are disclosed. A method of preparing the corrosion resistant ferromagnetic metal powders is also disclosed.
Inventors
- 👤 Masashi Aonuma
- 👤 Yasuo Tamai
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 11:21
CPC Classifications
H; H01; H01F; H01F1/00; H01F1/01; H01F1/03; H01F1/032; H01F1/04; H01F1/06; H01F1/061; B; B22; B22F; B22F1/00; B22F1/10; B22F1/102; G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/706; G11B5/70605; G11B5/70615; G11B5/70621
Claims Analysis
Total Claims: 79
Claim 1
Independent Claim
164 words
A method of preparing a corrosion-resistant ferromagnetic metal powder after forming said ferromagnetic metal powder comprising washing the formed ferromagnetic metal powder with a solution containing (a) at least one volatile corrosion inhibitor, said volatile corrosion inhibitor being an organic amine, amide or imide, or an organic or inorganic salt thereof, containing 1 to 4 nitrogen atoms and 1 to 12 carbon atoms and having a molecular weight of 50 to 200 and a vapor pressure of about 0.1×10 -5 to 1×10 2 mmHg at a temperature of 15° to 25° C.; (b) (1) water, (2) an organic solvent miscible with water, or (3) a mixture of water and at least one organic solvent miscible with water; and (c) an anionic surface active agent selected from the group consisting of a carboxylic acid or salt thereof, a salt of a sulfuric acid ester, a salt of a phosphoric acid ester, a salt of a dithiophosphoric acid ester and a salt of a sulfonic acid.
Claim 2
Independent Claim
164 words
A method of preparing a corrosion-resistant ferromagnetic metal powder after forming said ferromagnetic metal powder comprising washing the formed ferromagnetic metal powder with a solution containing (a) at least one volatile corrosion inhibitor, said volatile corrosion inhibitor being an organic amine, amide or imide, or an organic or inorganic salt thereof, containing 1 to 4 nitrogen atoms and 1 to 12 carbon atoms and having a molecular weight of 50 to 200 and a vapor pressure of about 0.1×10 -5 to 1×10 2 mmHg at a temperature of 15° to 25° C.; (b) (1) water, (2) an organic solvent miscible with water, or (3) a mixture of water and at least one organic solvent miscible with water; and (c) an anionic surface active agent selected from the group consisting of a carboxylic acid or salt thereof, a salt of a sulfuric acid ester, a salt of a phosphoric acid ester, a salt of a dithiophosphoric acid ester and a salt of a sulfonic acid.
Claim 3
Independent Claim
177 words
A method of preparing a corrosion resistant ferromagnetic metal powder after forming said ferromagnetic metal powder comprising washing the formed ferromagnetic metal powder with a solution containing (a) at least one volatile corrosion inhibitor, said volatile corrosion inhibitor being an organic amine, amide or imide, or an organic or inorganic salt thereof, containing 1 to 4 nitrogen atoms and 1 to 12 carbon atoms and having a molecular weight of 50 to 200 and a vapor pressure of about 0.1×10 -5 to 1×10 2 mmHg at a temperature of 15° to 25° C.; and (b) (1) water, (2) an organic solvent miscible with water, or (3) a mixture of water and at least one organic solvent miscible with water; and additionally contacting said ferromagnetic metal powder thereafter with an aqueous solution containing an anionic surface active agent selected from the group consisting of a carboxylic acid or salt thereof, a salt of a sulfuric acid ester, a salt of a phosphoric acid ester, a salt of a dithiophosphoric acid ester and a salt of a sulfonic acid.
Claim 4
Independent Claim
177 words
A method of preparing a corrosion resistant ferromagnetic metal powder after forming said ferromagnetic metal powder comprising washing the formed ferromagnetic metal powder with a solution containing (a) at least one volatile corrosion inhibitor, said volatile corrosion inhibitor being an organic amine, amide or imide, or an organic or inorganic salt thereof, containing 1 to 4 nitrogen atoms and 1 to 12 carbon atoms and having a molecular weight of 50 to 200 and a vapor pressure of about 0.1×10 -5 to 1×10 2 mmHg at a temperature of 15° to 25° C.; and (b) (1) water, (2) an organic solvent miscible with water, or (3) a mixture of water and at least one organic solvent miscible with water; and additionally contacting said ferromagnetic metal powder thereafter with an aqueous solution containing an anionic surface active agent selected from the group consisting of a carboxylic acid or salt thereof, a salt of a sulfuric acid ester, a salt of a phosphoric acid ester, a salt of a dithiophosphoric acid ester and a salt of a sulfonic acid.
Claim 5
Independent Claim
149 words
A method of preparing a corrosion resistant ferromagnetic metal powder after forming said ferromagnetic metal powder comprising drying the formed ferromagnetic metal powder in an atmosphere containing at least one volatile corrosion inhibitor, said volatile corrosion inhibitor being an organic amine, amide or imide, or an organic or inorganic salt thereof, containing 1 to 4 nitrogen atoms and 1 to 12 carbon atoms and having a molecular weight of 50 to 200 and a vapor pressure of about 0.1×10 -5 to 1×10 2 mmHg at a temperature of 15° to 25° C.; and additionally contacting said ferromagnetic metal powder with an aqueous solution containing an anionic surface active agent selected from the group consisting of a carboxylic acid or salt thereof, a salt of a sulfuric acid ester, a salt of a phosphoric acid ester, a salt of a dithiophosphoric acid ester and a salt of a sulfonic acid.
Claim 6
Independent Claim
149 words
A method of preparing a corrosion resistant ferromagnetic metal powder after forming said ferromagnetic metal powder comprising drying the formed ferromagnetic metal powder in an atmosphere containing at least one volatile corrosion inhibitor, said volatile corrosion inhibitor being an organic amine, amide or imide, or an organic or inorganic salt thereof, containing 1 to 4 nitrogen atoms and 1 to 12 carbon atoms and having a molecular weight of 50 to 200 and a vapor pressure of about 0.1×10 -5 to 1×10 2 mmHg at a temperature of 15° to 25° C.; and additionally contacting said ferromagnetic metal powder with an aqueous solution containing an anionic surface active agent selected from the group consisting of a carboxylic acid or salt thereof, a salt of a sulfuric acid ester, a salt of a phosphoric acid ester, a salt of a dithiophosphoric acid ester and a salt of a sulfonic acid.
Claim 7
Dependent Claim
61 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 1, in which the ferromagnetic metal powder has an average particle size of 50 to 1000 A, wherein each particle comprises at least about 75% by weight of a metal, and the metal contains at least one of Fe, Fe-Co, Fe-Ni, Co-Ni or Fe-Co-Ni as a main component.
Claim 8
Dependent Claim
61 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 2, in which the ferromagnetic metal powder has an average particle size of 50 to 1000 A, wherein each particle comprises at least about 75% by weight of a metal, and the metal contains at least one of Fe, Fe-Co, Fe-Ni, Co-Ni or Fe-Co-Ni as a main component.
Claim 9
Dependent Claim
61 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 3, in which the ferromagnetic metal powder has an average particle size of 50 to 1000 A, wherein each particle comprises at least about 75% by weight of a metal, and the metal contains at least one of Fe, Fe-Co, Fe-Ni, Co-Ni or Fe-Co-Ni as a main component.
Claim 10
Dependent Claim
28 words
The method of preparing a corrosion resistant ferromagnetic metal powder as claimed in claim 1, in which the volatile corrosion inhibitor is a nitrite of an organic amine.
Claim 11
Dependent Claim
28 words
The method of preparing a corrosion resistant ferromagnetic metal powder as claimed in claim 2, in which the volatile corrosion inhibitor is a nitrite of an organic amine.
Claim 12
Dependent Claim
28 words
The method of preparing a corrosion resistant ferromagnetic metal powder as claimed in claim 3, in which the volatile corrosion inhibitor is a nitrite of an organic amine.
Claim 13
Dependent Claim
28 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 7, in which the nitrite of an organic amine is dicyclohexylamine nitrite or diisopropylamine nitrite.
Claim 14
Dependent Claim
28 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 8, in which the nitrite of an organic amine is dicyclohexylamine nitrite or diisopropylamine nitrite.
Claim 15
Dependent Claim
28 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 9, in which the nitrite of an organic amine is dicyclohexylamine nitrite or diisopropylamine nitrite.
Claim 16
Dependent Claim
30 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 1, in which the anionic surface active agent is an alkali metal salt of an aliphatic acid.
Claim 17
Dependent Claim
30 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 2, in which the anionic surface active agent is an alkali metal salt of an aliphatic acid.
Claim 18
Dependent Claim
30 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 3, in which the anionic surface active agent is an alkali metal salt of an aliphatic acid.
Claim 19
Dependent Claim
30 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 1, wherein said ferromagnetic metal powder is the product of an oxidation-reduction reaction in an aqueous solution.
Claim 20
Dependent Claim
30 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 2, wherein said ferromagnetic metal powder is the product of an oxidation-reduction reaction in an aqueous solution.
Claim 21
Dependent Claim
30 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 3, wherein said ferromagnetic metal powder is the product of an oxidation-reduction reaction in an aqueous solution.
Claim 22
Dependent Claim
37 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 1, wherein the concentration of the volatile corrosion inhibitor in said solution is 0.005% by weight or more based on the total solution weight.
Claim 23
Dependent Claim
37 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 2, wherein the concentration of the volatile corrosion inhibitor in said solution is 0.005% by weight or more based on the total solution weight.
Claim 24
Dependent Claim
28 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 19, wherein the concentration of the volatile corrosion inhibitor is 0.01 to 20% by weight.
Claim 25
Dependent Claim
28 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 20, wherein the concentration of the volatile corrosion inhibitor is 0.01 to 20% by weight.
Claim 26
Dependent Claim
40 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 1, wherein the ferromagnetic metal powder is washed with water containing said volatile corrosion inhibitor and the pH of the solution is about 5 to about 9.
Claim 27
Dependent Claim
40 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 2, wherein the ferromagnetic metal powder is washed with water containing said volatile corrosion inhibitor and the pH of the solution is about 5 to about 9.
Claim 28
Dependent Claim
26 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 1, wherein the temperature employed during the washing is 120° C. or less.
Claim 29
Dependent Claim
26 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 2, wherein the temperature employed during the washing is 120° C. or less.
Claim 30
Dependent Claim
26 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 3, wherein the temperature employed during the drying is 120° C. or less.
Claim 31
Dependent Claim
39 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 3, wherein the ferromagnetic metal powder is dried in an atmosphere containing said volatile corrosion inhibitor and the pressure is from about 0.5 to 5 atmospheres.
Claim 32
Dependent Claim
54 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 3, wherein the ferromagnetic metal powder is dried in an atmosphere containing said volatile corrosion inhibitor and said volatile corrosion inhibitor is present in an amount of from about 10 g/m 3 to about 2 Kg/m 3 of the treating atmosphere.
Claim 33
Dependent Claim
29 words
The method of preparing a corrosion-resistant feromagnetic metal powder as claimed in claim 1, wherein the ferromagnetic metal powder is washed and the pressure is 0.5 to 5 atmospheres.
Claim 34
Dependent Claim
29 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 2, wherein the ferromagnetic metal powder is washed and the pressure is 0.5 to 5 atmospheres.
Claim 35
Dependent Claim
28 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 1, wherein the contact time with said ferromagnetic metal powder is at least 1 minute.
Claim 36
Dependent Claim
28 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 2, wherein the contact time with said ferromagnetic metal powder is at least 1 minute.
Claim 37
Dependent Claim
28 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 3, wherein the contact time with said ferromagnetic metal powder is at least 1 minute.
Claim 38
Dependent Claim
61 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 1, wherein said volatile corrosion inhibitor has a high vapor pressure of 1×10 -2 to 1×10 2 mmHg at 20° C. and is used in combination with a volatile corrosion inhibitor having a lower vapor pressure of 0.1×10 -5 to less than 1×10 -2 mmHg at 20° C.
Claim 39
Dependent Claim
61 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 2, wherein said volatile corrosion inhibitor has a high vapor pressure of 1×10 -2 to 1×10 2 mmHg at 20° C. and is used in combination with a volatile corrosion inhibitor having a lower vapor pressure of 0.1×10 -5 to less than 1×10 -2 mmHg at 20° C.
Claim 40
Dependent Claim
61 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 3, wherein said volatile corrosion inhibitor has a high vapor pressure of 1×10 -2 to 1×10 2 mmHg at 20° C. and is used in combination with a volatile corrosion inhibitor having a lower vapor pressure of 0.1×10 -5 to less than 1×10 -2 mmHg at 20° C.
Claim 41
Dependent Claim
45 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 35, wherein the high vapor pressure volatile corrosion inhibitor is cyclohexylammonium carbonate, diisopropylamine nitrate, or guanidine carbonate and the low vapor pressure volatile corrosion inhibitor is dicyclohexylamine nitrite, dicyclohexylamine chromate or hexamethylenetetraamine.
Claim 42
Dependent Claim
45 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 36, wherein the high vapor pressure volatile corrosion inhibitor is cyclohexylammonium carbonate, diisopropylamine nitrate, or guanidine carbonate and the low vapor pressure volatile corrosion inhibitor is dicyclohexylamine nitrite, dicyclohexylamine chromate or hexamethylenetetraamine.
Claim 43
Dependent Claim
45 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 37, wherein the high vapor pressure volatile corrosion inhibitor is cyclohexylammonium carbonate, diisopropylamine nitrate, or guanidine carbonate and the low vapor pressure volatile corrosion inhibitor is dicyclohexylamine nitrite, dicyclohexylamine chromate or hexamethylenetetraamine.
Claim 44
Dependent Claim
46 words
The method of preparing a corrosion resistant ferromagnetic metal powder as claimed in claim 1, wherein said ferromagnetic metal powder comprises the product obtained on thermally decomposing an organic acid salt of a ferromagnetic metal and then reducing the thermal decomposition product with a reducing gas.
Claim 45
Dependent Claim
46 words
The method of preparing a corrosion resistant ferromagnetic metal powder as claimed in claim 2, wherein said ferromagnetic metal powder comprises the product obtained on thermally decomposing an organic acid salt of a ferromagnetic metal and then reducing the thermal decomposition product with a reducing gas.
Claim 46
Dependent Claim
46 words
The method of preparing a corrosion resistant ferromgnetic metal powder as claimed in claim 3, wherein said ferromagnetic metal powder comprises the product obtained on thermally decomposing an organic acid salt of a ferromagnetic metal and then reducing the thermal decomposition product with a reducing gas.
Claim 47
Dependent Claim
44 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 1, wherein said ferromagnetic metal powder is the product obtained on reducing needle-like iron oxyhydroxides, needle-like iron oxyhydroxides having a metal contained therein or needle-like iron oxides obtained from these hydroxides.
Claim 48
Dependent Claim
44 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 2, wherein said ferromagnetic metal powder is the product obtained on reducing needle-like iron oxyhydroxides, needle-like iron oxyhydroxides having a metal contained therein or needle-like iron oxides obtained from these hydroxides.
Claim 49
Dependent Claim
44 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 3, wherein said ferromagnetic metal powder is the product obtained on reducing needle-like iron oxyhydroxides, needle-like iron oxyhydroxides having a metal contained therein or needle-like iron oxides obtained from these hydroxides.
Claim 50
Dependent Claim
35 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 1, wherein said ferromagnetic metal powder is the product obtained on evaporating a ferromagnetic metal in an inert gas under low pressure.
Claim 51
Dependent Claim
35 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 2, wherein said ferromagnetic metal powder is the product obtained on evaporating a ferromagnetic metal in an inert gas under low pressure.
Claim 52
Dependent Claim
35 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 3, wherein said ferromagnetic metal powder is the product obtained on evaporating a ferromagnetic metal in an inert gas under low pressure.
Claim 53
Dependent Claim
31 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 1, wherein said ferromagnetic metal powder is the product obtained on thermally decomposing a ferromagnetic metal carbonyl compound.
Claim 54
Dependent Claim
31 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 2, wherein said ferromagnetic metal powder is the product obtained on thermally decomposing a ferromagnetic metal carbonyl compound.
Claim 55
Dependent Claim
31 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 3, wherein said ferromagnetic metal powder is the product obtained on thermally decomposing a ferromagnetic metal carbonyl compound.
Claim 56
Dependent Claim
43 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 1, wherein said ferromagnetic metal powder is the product obtained on electrodepositing a ferromagnetic metal powder using a mercury cathode and then separating the ferromagnetic metal powder from the mercury.
Claim 57
Dependent Claim
43 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 2, wherein said ferromagnetic metal powder is the product obtained on electrodepositing a ferromagnetic metal powder using a mercury cathode and then separating the ferromagnetic metal powder from the mercury.
Claim 58
Dependent Claim
43 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 3, wherein said ferromagnetic metal powder is the product obtained on electrodepositing a ferromagnetic metal powder using a mercury cathode and then separating the ferromagnetic metal powder from the mercury.
Claim 59
Dependent Claim
42 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 1, wherein said ferromagnetic metal powder is the product obtained on adding a reducing agent to a solution containing a salt of a ferromagnetic metal to reduce the salt.
Claim 60
Dependent Claim
42 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 2, wherein said ferromagnetic metal powder is the product obtained on adding a reducing agent to a solution containing a salt of a ferromagnetic metal to reduce the salt.
Claim 61
Dependent Claim
42 words
The method of preparing a corrosion-resistant ferromagnetic metal powder as claimed in claim 3, wherein said ferromagnetic metal powder is the product obtained on adding a reducing agent to a solution containing a salt of a ferromagnetic metal to reduce the salt.
Claim 62
Dependent Claim
46 words
Corrosion-resistant ferromagnetic metal powder characterized in that a volatile corrosion inhibitor is adsorbed on at least a part of the surface of a ferromagnetic metal powder having an average particle size of about 1,000 A or less, produced by the method as claimed in claim 1.
Claim 63
Dependent Claim
46 words
Corrosion-resistant ferromagnetic metal powder characterized in that a volatile corrosion inhibitor is adsorbed on at least a part of the surface of a ferromagnetic metal powder having an average particle size of about 1,000 A or less, produced by the method as claimed in claim 2.
Claim 64
Dependent Claim
46 words
Corrosion-resistant ferromagnetic metal powder characterized in that a volatile corrosion inhibitor is adsorbed on at least a part of the surface of a ferromagnetic metal powder having an average particle size of about 1,000 A or less, produced by the method as claimed in claim 3.
Claim 65
Dependent Claim
60 words
Corrosion-resistant ferromagnetic metal powder produced by the method as claimed in claim 1, in which the ferromagnetic metal powder has an average particle size of 50 to 1,000 A, wherein each particle comprises at least about 75% by weight of a metal, and said metal contains at least one of Fe, Fe-Co, Fe-Ni, Co-Ni or Fe-Co-Ni as a main component.
Claim 66
Dependent Claim
60 words
Corrosion-resistant ferromagnetic metal powder produced by the method as claimed in claim 2, in which the ferromagnetic metal powder has an average particle size of 50 to 1,000 A, wherein each particle comprises at least about 75% by weight of a metal, and said metal contains at least one of Fe, Fe-Co, Fe-Ni, Co-Ni or Fe-Co-Ni as a main component.
Claim 67
Dependent Claim
60 words
Corrosion-resistant ferromagnetic metal powder produced by the method as claimed in claim 3, in which the ferromagnetic metal powder has an average particle size of 50 to 1,000 A, wherein each particle comprises at least about 75% by weight of a metal, and said metal contains at least one of Fe, Fe-Co, Fe-Ni, Co-Ni or Fe-Co-Ni as a main component.
Claim 68
Dependent Claim
26 words
Corrosion-resistant ferromagnetic metal powder produced by the method as claimed in claim 1, in which the volatile corrosion inhibitor is a nitrite of an organic amine.
Claim 69
Dependent Claim
26 words
Corrosion-resistant ferromagnetic metal powder produced by the method as claimed in claim 2, in which the volatile corrosion inhibitor is a nitrite of an organic amine.
Claim 70
Dependent Claim
26 words
Corrosion-resistant ferromagnetic metal powder produced by the method as claimed in claim 3, in which the volatile corrosion inhibitor is a nitrite of an organic amine.
Claim 71
Dependent Claim
23 words
Corrosion-resistant ferromagnetic metal powder as claimed in claim 65, in which the nitrite of an organic amine is dicyclohexylamine nitrite or diisopropylamine nitrite.
Claim 72
Dependent Claim
23 words
Corrosion-resistant ferromagnetic metal powder as claimed in claim 66, in which the nitrite of an organic amine is dicyclohexylamine nitrite or diisopropylamine nitrite.
Claim 73
Dependent Claim
23 words
Corrosion-resistant ferromagnetic metal powder as claimed in claim 67, in which the nitrite of an organic amine is dicyclohexylamine nitrite or diisopropylamine nitrite.
Claim 74
Dependent Claim
13 words
A ferromagnetic metal powder produced by the process as claimed in claim 1.
Claim 75
Dependent Claim
13 words
A ferromagnetic metal powder produced by the process as claimed in claim 2.
Claim 76
Dependent Claim
13 words
A ferromagnetic metal powder produced by the process as claimed in claim 3.
Claim 77
Dependent Claim
18 words
A magnetic recording medium comprising a ferromagnetic metal powder produced by the process as claimed in claim 1.
Claim 78
Dependent Claim
18 words
A magnetic recording medium comprising a ferromagnetic metal powder produced by the process as claimed in claim 2.
Claim 79
Dependent Claim
18 words
A magnetic recording medium comprising a ferromagnetic metal powder produced by the process as claimed in claim 3.
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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) | 1984-03-02 | 1984-09-01 | 1985-03-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-03-02 | 1988-09-01 | 1989-03-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-03-02 | 1992-09-01 | 1993-03-03 | $7700.00 | Window Closed / Lapsed |