US4996022A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for producing a sintered body
Assignee: Juki Corp
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Filing: 1990-07-10
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Granted: 1991-02-26
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Expires: 2010-07-10
Abstract
Abstract A sintered body is produced by a process comprising the steps of mixing one or more metal powder particles with an organic binder, injection-molding the mixture to form a green body of a predetermined shape, removing the binder from the green body to form a porous body substantially made of the metal powder, and heating the porous body to a sintering temperature and holding it at that temperature to produce a sintered body, in which process the binder is removed through the sequence of the following steps: preheating the green body in an inert gas atmosphere in a temperature range that creates open pores in it; placing the green body, in which open pores have started to form, in a hydrogen gas atmosphere optionally mixed with an inert gas; holding the green body in a temperature range where the metal powder is not carburized and where the open pores will be maintained, so that the greater part of the binder is removed to form a porous body that is substantially made of the metal powder alone; and further holding said porous body at said heating temperature for a sufficient period of time to vaporize the carbon in the small amount of residual binder in the porous body through reaction with hydrogen.
Inventors
- 👤 Norikazu Shindo
- 👤 Tomoyuki Sekine
- 👤 Yoshikatsu Nakamura
- 👤 Takashi Kawamoto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 02:04
CPC Classifications
B; B22; B22F; B22F3/00; B22F3/22; B22F3/225; B22F3/10; B22F3/1017; B22F3/1021; B22F2201/00; B22F2201/01; B22F2201/02; B22F2201/20; B22F2998/00
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
211 words
In a process for producing a sintered body comprising the steps of mixing one or more metal powder particles with an organic binder, injection-molding the mixture to form a green body of a predetermined shape, removing the binder from the green body to form a porous body substantially composed of the metal powder, and heating the porous body to a sintering temperature and holding it at that temperature to produce a sintered body, the improvement wherein the binder is removed through the sequence of the following steps: preheating the green body in an inert gas atmosphere in a temperature range that creates open pores in it; placing the green body, in which open pores have started to form, in a hydrogen gas atmosphere optionally mixed with an inert gas; holding the green body in a temperature range where the metal powder is not carburized and where the open pores will be maintained, so that the greater part of the binder is removed to form a porous body that is substantially made of the metal powder alone; and further holding said porous body at said heating temperature for a sufficient period of time to vaporize the carbon in the small amount of residual binder in the porous body through reaction with hydrogen.
Claim 2
Dependent Claim
211 words
In a process for producing a sintered body comprising the steps of mixing one or more metal powder particles with an organic binder, injection-molding the mixture to form a green body of a predetermined shape, removing the binder from the green body to form a porous body substantially composed of the metal powder, and heating the porous body to a sintering temperature and holding it at that temperature to produce a sintered body, the improvement wherein the binder is removed through the sequence of the following steps: preheating the green body in an inert gas atmosphere in a temperature range that creates open pores in it; placing the green body, in which open pores have started to form, in a hydrogen gas atmosphere optionally mixed with an inert gas; holding the green body in a temperature range where the metal powder is not carburized and where the open pores will be maintained, so that the greater part of the binder is removed to form a porous body that is substantially made of the metal powder alone; and further holding said porous body at said heating temperature for a sufficient period of time to vaporize the carbon in the small amount of residual binder in the porous body through reaction with hydrogen.
Claim 3
Dependent Claim
18 words
The process according to claim 1 wherein the hydrogen content of said gaseous mixture is at least 5%.
Claim 4
Dependent Claim
22 words
The process according to claim 1 or 2 wherein the binder is removed at a temperature in the range of 600°-800° C.
Claim 5
Dependent Claim
34 words
The process according to claim 1 or 2 wherein the porous body obtained by removing the binder from said green body is presintered by elevating its temperature, with the presintered body being subsequently sintered.
Claim 6
Dependent Claim
15 words
The process according to claim 4 wherein the temperature for presintering is at 600°-800° C.
Claim 7
Dependent Claim
32 words
The process according to claim 3 wherein the porous body obtained by removing the binder from said green body is presintered by elevating its temperature, with the presintered body being subsequently sintered.
Claim 8
Dependent Claim
15 words
The process according to claim 6 wherein the temperature for presintering is at 600°-800° C.
Claim 9
Dependent Claim
15 words
The process according to claim 4 wherein the temperature for presintering is about 700° C.
Claim 10
Dependent Claim
15 words
The process according to claim 7 wherein the temperature for presintering is about 700° C.
Claim 11
Dependent Claim
11 words
The process according to claim 1 wherein said metal is iron.
Claim 12
Dependent Claim
11 words
The process according to claim 7 wherein said metal is iron.
Claim 13
Dependent Claim
16 words
The process according to claim 1 wherein iron carbonyl powder is mixed with a thermoplastic binder.
Claim 14
Dependent Claim
24 words
The process according to claim 7 wherein 60 vol. % of iron carbonyl powder is mixed with 40 vol. % of a thermoplastic binder.
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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) | 1994-02-25 | 1994-08-27 | 1995-02-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-02-25 | 1998-08-27 | 1999-02-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-02-25 | 2002-08-27 | 2003-02-26 | $7700.00 | Window Closed / Lapsed |