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EP0052922A1
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EP
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Dimensionally-controlled cobalt-containing precision molded metal article
Assignee: 3M Co
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Filing: 1981-09-10
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Granted: —
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Expires: 2001-09-10
Abstract
Abstract Counteracting of the shrinkage normally encountered in the powder metallurgy process of moulding a mixture of spherical cobalt-containing particles (1) and thermoplastic binder, heating the resulting moulded article to degrade the binder and form a porous preform, and infiltrating the same infiltrant (19) by adding finely divided elemental iron or elemental nickel to the spherical cobalt-contaihing particles iron or nickel forming with other elements coating (3). In addition to improving dimensional control, the elemental powder addition increases impact strength while maintaining hardness.
Inventors
- 👤 Kenneth R. Dillon
- 👤 Richard L. Terchek
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-07 21:24
CPC Classifications
B; B22; B22F; B22F3/00; B22F3/24; B22F3/26; C; C22; C22C; C22C1/00; C22C1/04; C22C1/05; C22C1/051; B22F2998/00; B22F2998/10; Y; Y10; Y10T; Y10T428/00; Y10T428/12; Y10T428/12014; Y10T428/1216; Y10T428/12167
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
168 words
A shaped, homogeneous, monolithic metal article, containing (A) a skeleton, comprising a plurality of generally spherical domains having an average diameter less than 200 micrometers, said domains, when viewed using backscattered electron imaging, comprising granules of chromium carbide homogeneously dispersed throughout a first solid solution comprising cobalt and chromium, and either iron, nickel, or both iron and nickel, and (B) infiltrant, comprising a continuous phase of metal or alloy occupying the volume of said article not occupied by said skeleton, said skeleton and said infiltrant thereby comprising two intermeshed matrices and said article being substantially void-free, characterized in that said skeleton contains a second solid solution comprising cobalt, chromium, and either iron, nickel, or both iron and nickel, said second solid solution: (i) containing a greater percentage of cobalt and a lesser percentage of chromium than said first solid solution, (ii) being essentially free of carbides, and (iii) enveloping the majority of said spherical domains, the so-enveloped domains and second solid solution being interconnected to form said skeleton.
Claim 2
Dependent Claim
168 words
A shaped, homogeneous, monolithic metal article, containing (A) a skeleton, comprising a plurality of generally spherical domains having an average diameter less than 200 micrometers, said domains, when viewed using backscattered electron imaging, comprising granules of chromium carbide homogeneously dispersed throughout a first solid solution comprising cobalt and chromium, and either iron, nickel, or both iron and nickel, and (B) infiltrant, comprising a continuous phase of metal or alloy occupying the volume of said article not occupied by said skeleton, said skeleton and said infiltrant thereby comprising two intermeshed matrices and said article being substantially void-free, characterized in that said skeleton contains a second solid solution comprising cobalt, chromium, and either iron, nickel, or both iron and nickel, said second solid solution: (i) containing a greater percentage of cobalt and a lesser percentage of chromium than said first solid solution, (ii) being essentially free of carbides, and (iii) enveloping the majority of said spherical domains, the so-enveloped domains and second solid solution being interconnected to form said skeleton.
Claim 3
Dependent Claim
22 words
An article according to Claim 1, further characterized in that granules of tungsten carbide are homogeneously dispersed throughout said first solid solution.
Claim 4
Dependent Claim
38 words
An article according to any preceding claim, further characterized in that the total content of iron and nickel in said second solid solution is greater than the total content of iron and nickel in said first solid solution.
Claim 5
Dependent Claim
43 words
An article according to any preceding claim, further characterized in that the percentage content of iron plus nickel in said second solid solution is 1.3 or more times as great as the percentage content of iron plus nickel in said first solid solution.
Claim 6
Dependent Claim
30 words
An article according to any preceding claim, further characterized in that said first solid solution contains 6% or more iron, and said second solid solution contains 7% or more iron.
Claim 7
Dependent Claim
30 words
An article according to any preceding claim, further characterized in that said first solid solution contains 10% or more iron, and said second solid solution contains 13% or more iron.
Claim 8
Dependent Claim
23 words
An article according to any preceding claim, further characterized in that said spherical domains have an average diameter between 1 and 44 micrometers.
Claim 9
Dependent Claim
41 words
An article according to any preceding claim, further characterized in that the portions of said second solid solution enveloping individual spherical domains have an average thickness, measured radially outward from the center of such spherical domains, of 5 micrometers or less.
Claim 10
Dependent Claim
8 words
A die cavity according to any preceding claim.
Claim 11
Dependent Claim
157 words
A process for making infiltrated molded metal articles according to Claim 1 characterized in that there is molded in a flexible mold of a master a plastic mixture of spherical cobalt-containing powder and heat fugitive binder comprising thermoplastic material to which has been added up to 11% by weight, based on the weight of said spherical cobalt-containing powder, of elemental iron or elemental nickel particles having an average particle diameter less than 10 micrometers, whereupon (A) a green article of predetermined shape and dimensions so obtained is (i) removed from said mold, and (ii) heated to remove said binder and consolidate said spherical cobalt-containing powder in the form of a porous, monolithic skeleton of particles of cobalt-containing metal, (B) said skeleton is infiltrated with a molten metal having a melting point that is at least 25°C less than the melting point of the lowest melting of said cobalt-containing metal particles, and (C) said infiltrated skeleton is cooled.
References Cited (Backward Citations)
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