Patent US4849164A successfully refreshed from Google Patents.
US4849164A
Expired / Lapsed
US
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Method of producing iron powder article
Assignee: Motors Liquidation Co
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Filing: 1988-02-29
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Granted: 1989-07-18
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Expires: 2008-02-29
Abstract
Abstract A sintering aid is disclosed for use in a powder metallurgical method for manufacturing an iron alloy article by compacting and sintering a predominantly iron powder mixture comprising carbon powder and a boron-containing additive, such as nickel boride. The sintering aid comprises an oxygen getter to inhibit boron oxidation that, if formed, is believed to retard carbon diffusion. The sintering aid also preferably includes a second constituent to produce, in combination with the getter, a melting point suitable for forming a transient liquid phase during the early stages of sintering. Preferred sintering aids include intermetallic iron titanium compounds, intermetallic ferro-vanadium compound and intermetallic nickel magnesium compound.
Inventors
- 👤 William F. Jandeska
- 👤 Vadim Rezhets
- 👤 Carlo Ligotti
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 09:13
CPC Classifications
B; B22; B22F; B22F3/00; B22F3/10; B22F3/1003; C; C22; C22C; C22C33/00; C22C33/02; C22C33/0207
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
112 words
In a method for manufacturing an iron alloy article by compacting and sintering a powder mixture composed predominantly of iron powder and comprising carbon powder and a boron-containing powder, said sintering being carried out at an elevated temperature to bond the mixture into an integral iron-base structure and diffusing the carbon and the boron into the structure, the improvement comprising including in said mixture prior to compaction a sintering aid comprising a metallic constituent preferentially reactive with oxygen relative to boron, said sintering aid being formulated to form a transient liquid phase during sintering, to inhibit boron oxidation and thereby to promote diffusion of said carbon and boron into the iron structure.
Claim 2
Dependent Claim
112 words
In a method for manufacturing an iron alloy article by compacting and sintering a powder mixture composed predominantly of iron powder and comprising carbon powder and a boron-containing powder, said sintering being carried out at an elevated temperature to bond the mixture into an integral iron-base structure and diffusing the carbon and the boron into the structure, the improvement comprising including in said mixture prior to compaction a sintering aid comprising a metallic constituent preferentially reactive with oxygen relative to boron, said sintering aid being formulated to form a transient liquid phase during sintering, to inhibit boron oxidation and thereby to promote diffusion of said carbon and boron into the iron structure.
Claim 3
Dependent Claim
139 words
In a method for manufacturing an iron alloy article by compacting and sintering a powder mixture composed predominantly of iron powder and comprising carbon powder and a boron-containing powder, said sintering being carried out at an elevated temperature to bond the mixture into an integral iron-base structure and diffusing the carbon and the boron into the structure, the improvement comprising adding to said mixture prior to compaction a sintering aid suitable for forming a transient liquid phase during sintering and comprising a preferentially oxygen-reactive metallic constituent having a standard free energy of oxide formation at sintering temperatures less than the standard free energy of oxide formation of boron, such that said constituent reacts with oxygen within said compact during sintering to inhibit oxidation of said boron and thereby to promote diffusion of carbon and boron into the iron structure.
Claim 4
Dependent Claim
139 words
In a method for manufacturing an iron alloy article by compacting and sintering a powder mixture composed predominantly of iron powder and comprising carbon powder and a boron-containing powder, said sintering being carried out at an elevated temperature to bond the mixture into an integral iron-base structure and diffusing the carbon and the boron into the structure, the improvement comprising adding to said mixture prior to compaction a sintering aid suitable for forming a transient liquid phase during sintering and comprising a preferentially oxygen-reactive metallic constituent having a standard free energy of oxide formation at sintering temperatures less than the standard free energy of oxide formation of boron, such that said constituent reacts with oxygen within said compact during sintering to inhibit oxidation of said boron and thereby to promote diffusion of carbon and boron into the iron structure.
Claim 5
Dependent Claim
139 words
In a method for manufacturing an iron alloy article by compacting and sintering a powder mixture composed predominantly of iron powder and comprising carbon powder and a boron-containing powder, said sintering being carried out at an elevated temperature to bond the mixture into an integral iron-base structure and diffusing the carbon and the boron into the structure, the improvement comprising including in the powder mixture prior to compaction a powder comprising a preferentially oxygen-reactive constituent selected from the group consisting of titanium, vanadium, magnesium and rare earth elements and a melting point depressant constituent suitable in combination with said oxygen-reactive constituent for reducing the melting point of said sintering aid to form a transient liquid phase during sintering, such that during sintering the oxygen-reactive constituent inhibits boron oxidation and promotes diffusion of carbon and boron into the iron structure.
Claim 6
Dependent Claim
139 words
In a method for manufacturing an iron alloy article by compacting and sintering a powder mixture composed predominantly of iron powder and comprising carbon powder and a boron-containing powder, said sintering being carried out at an elevated temperature to bond the mixture into an integral iron-base structure and diffusing the carbon and the boron into the structure, the improvement comprising including in the powder mixture prior to compaction a powder comprising a preferentially oxygen-reactive constituent selected from the group consisting of titanium, vanadium, magnesium and rare earth elements and a melting point depressant constituent suitable in combination with said oxygen-reactive constituent for reducing the melting point of said sintering aid to form a transient liquid phase during sintering, such that during sintering the oxygen-reactive constituent inhibits boron oxidation and promotes diffusion of carbon and boron into the iron structure.
Claim 7
Dependent Claim
23 words
The method according to claim 3 wherein the melting point depressant constituent is selected from the group consisting of iron, copper and nickel.
Claim 8
Dependent Claim
14 words
The method according to claim 4 wherein the sintering aid comprises iron titanium alloy.
Claim 9
Dependent Claim
16 words
The method according to claim 4 wherein the sintering aid is composed of intermetallic ferro-vanadium compound.
Claim 10
Dependent Claim
17 words
The method according to claim 4 wherein the sintering aid is composed of intermetallic nickel magnesium compound.
Claim 11
Dependent Claim
13 words
The method according to claim 4 wherein the sintering aid further comprises boron.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-07-17 | 1993-01-16 | 1993-07-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-07-17 | 1997-01-16 | 1997-07-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-07-17 | 2001-01-16 | 2001-07-18 | $7700.00 | Window Closed / Lapsed |