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Patent US4436696A successfully refreshed from Google Patents.
US4436696A
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US
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Process for providing a uniform carbon distribution in ferrous compacts at high temperatures
Assignee: Air Products and Chemicals Inc
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Filing: 1981-05-20
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Granted: 1984-03-13
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Expires: 2001-05-20
Abstract
Abstract A process for high temperature sintering of ferrous powder metallurgy compacts having a substantially uniform carbon distribution which comprises: (a) heating the ferrous powder metallurgy compact in the heating zone of a sintering furnace to a temperature of about 2,300° to 2,550° F. (1,260° to 1,399° C.), (b) introducing to the heating zone an atmosphere comprising about 2 to less than 10 volume percent hydrogen, about 0.5 to 2.0 volume percent carbon monoxide, about 0.5 to 1.0 volume percent methane and the balance nitrogen, and (c) removing the sintered product from the furnace.
Inventors
- 👤 Daniel M. Buck
- 👤 Alan T. Sibley
- 👤 John J. Kaiser
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 12:18
CPC Classifications
C; C22; C22C; C22C33/00; C22C33/02; B; B22; B22F; B22F3/00; B22F3/10; B22F3/1003; B22F3/1007
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
123 words
A process for high temperature sintering which provides a substantially uniform carbon distribution in a ferrous powder metallurgy compact, which process comprises: (a) heating the ferrous powder metallurgy compact in the heating zone of a sintering furnace to a temperature of at least 2,200° F., (b) introducing into the heating zone an atmosphere comprising about 2 to less than 10 volume percent hydrogen, about 0.5 to 2.0 volume percent carbon monoxide, about 0.5 to 1.0 volume percent methane, the level of either the carbon monoxide or the methane being at least slightly greater than 0.5 volume percent when the other is about 0.5 volume percent and the hydrogen is about 2 volume percent, and the balance nitrogen, and (c) removing the sintered compact.
Claim 2
Dependent Claim
123 words
A process for high temperature sintering which provides a substantially uniform carbon distribution in a ferrous powder metallurgy compact, which process comprises: (a) heating the ferrous powder metallurgy compact in the heating zone of a sintering furnace to a temperature of at least 2,200° F., (b) introducing into the heating zone an atmosphere comprising about 2 to less than 10 volume percent hydrogen, about 0.5 to 2.0 volume percent carbon monoxide, about 0.5 to 1.0 volume percent methane, the level of either the carbon monoxide or the methane being at least slightly greater than 0.5 volume percent when the other is about 0.5 volume percent and the hydrogen is about 2 volume percent, and the balance nitrogen, and (c) removing the sintered compact.
Claim 3
Dependent Claim
50 words
The process of claim 1 in which a mixture comprising nitrogen, methanol and 0.5 to 1.0 volume percent methane is introduced into the heating zone, the nitrogen and methanol being in such proportion to afford when subjected to the high temperature in the heating zone the atmosphere of step (b).
Claim 4
Dependent Claim
23 words
The process of claim 1 in which the ferrous powder metallurgy compact is heated to a temperature from about 2,300° to 2,550° F.
Claim 5
Dependent Claim
22 words
The process of claim 1, 2 or 3 in which hydrogen content of the atmosphere is about 2 to 6 volume percent.
Claim 6
Dependent Claim
20 words
The process of claim 4 in which the hydrogen content of the atmosphere is about 2 to 4.5 volume percent.
Claim 7
Dependent Claim
27 words
The process of claim 1, 2 or 3 in which the ferrous powder metallurgy compact has a medium to high combined carbon content of at least 0.4%.
Claim 8
Dependent Claim
16 words
The process of claim 3 in which the ferrous powder metallurgy compact contains copper or nickel.
Claim 9
Dependent Claim
136 words
A process for high temperature sintering which provides a substantially uniform carbon distribution in a ferrous powder metallurgy compact having a medium to high combined carbon content of at least 0.4%, which process comprises: (a) heating the ferrous powder metallurgy compact in the heating zone of a sintering furnace to a temperature from about 2,300° to 2,550° F., (b) introducing to the heating zone an atmosphere comprising about 2 to less than 10 volume percent hydrogen, about 0.5 to 2.0 volume percent carbon monoxide, about 0.5 to 1.0 volume percent methane, the level of either the carbon monoxide or the methane being a least slightly greater than 0.5 volume percent when the other is about 0.5 volume percent and the hydrogen is about 2 volume percent, and the balance nitrogen, and (c) removing the sintered compact.
Claim 10
Dependent Claim
136 words
A process for high temperature sintering which provides a substantially uniform carbon distribution in a ferrous powder metallurgy compact having a medium to high combined carbon content of at least 0.4%, which process comprises: (a) heating the ferrous powder metallurgy compact in the heating zone of a sintering furnace to a temperature from about 2,300° to 2,550° F., (b) introducing to the heating zone an atmosphere comprising about 2 to less than 10 volume percent hydrogen, about 0.5 to 2.0 volume percent carbon monoxide, about 0.5 to 1.0 volume percent methane, the level of either the carbon monoxide or the methane being a least slightly greater than 0.5 volume percent when the other is about 0.5 volume percent and the hydrogen is about 2 volume percent, and the balance nitrogen, and (c) removing the sintered compact.
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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) | 1987-03-13 | 1987-09-12 | 1988-03-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-03-13 | 1991-09-12 | 1992-03-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-03-13 | 1995-09-12 | 1996-03-13 | $7700.00 | Window Closed / Lapsed |