EP0533745B1 - Procede de fabrication de produits composes - Google Patents

Procede de fabrication de produits composes Download PDF

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Publication number
EP0533745B1
EP0533745B1 EP91910811A EP91910811A EP0533745B1 EP 0533745 B1 EP0533745 B1 EP 0533745B1 EP 91910811 A EP91910811 A EP 91910811A EP 91910811 A EP91910811 A EP 91910811A EP 0533745 B1 EP0533745 B1 EP 0533745B1
Authority
EP
European Patent Office
Prior art keywords
preformed
powder
capsule
loose
sintered
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP91910811A
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German (de)
English (en)
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EP0533745A1 (fr
Inventor
Sigurd Friborg
Kurt Lill
Krister Torssell
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ABB AB
Original Assignee
Asea Brown Boveri AB
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Filing date
Publication date
Application filed by Asea Brown Boveri AB filed Critical Asea Brown Boveri AB
Publication of EP0533745A1 publication Critical patent/EP0533745A1/fr
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F7/00—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression
    • B22F7/06—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite workpieces or articles from parts, e.g. to form tipped tools

Definitions

  • the invention relates to method of manufacturing compound products according to the precharacterising part of claim 1. Such a method is known from the WO-A-8502570.
  • the method according to the invention belongs to those which deal with compaction of at least two powder materials into products with essentially full density while at the same time a metallic bond between the materials included in obtained.
  • the invention is particularly applicable to the manufacture of products in which property combinations are required which are normally not obtained with the same material, for example good erosion and corrosion properties or great hardness combined with toughness, good thermal conductivity or thermal shock resistance.
  • One of or all the materials may in certain cases be preformed into solid bodies, which are placed in a capsule and compressed.
  • the powder may be filled around the solid preformed bodies, whereafter the powder is compacted together with the solid bodies. Differences in density between the solid bodies and the loose powder lead to powder and body being compacted to varying degrees during the pressing operation. In certain cases this gives rise to internal stresses or other imperfections in the compound product, which limits the applications of the compound technique since for certain fields of application, material combinations or product geometries, for which these internal imperfections cannot be tolerated, the optimum solutions which can be obtained with compound technique must be dispensed with.
  • the WO-A-8502570 describes a method for manufacturing a tool for shaping material.
  • the tool consists of two components of material of different properties, one material for the shaping surface of the tool, which effects the actual shaping work, and the other material for supporting said surface material.
  • To manufacture this tool an enlarged model with exhibits the shaping surface of the tool is first placed into a pressure sintering chamber. Then, a powder to form the surface layer of the tool is applied to the model and thereafter a powder which is supposed to form the support for the surface layer is applied against the first mentioned powder. Then the powders are pressure sintered into a solid body.
  • the boundary layer between the model and the powder forming the surface of the tool comprises a material which, during the sintering process, will not fuse or bind together in order to allow the model to be removed upon completion of the sintering process.
  • the invention aims at developing a method of manufacturing compound products which avoids the above mentioned problems with the removal of partitions as well as the problem with different degrees of compaction in different parts of the compound product by preforming bodies.
  • the invention suggests a method of manufacturing compound products according to the introductory part of claim 1, which is characterized by the features of the characterizing part of claim 1.
  • the preformed bodies are compacted and sintered into essentially the same density as the components which are subjected to the pressure sintering in the form of loose powder.
  • At least one of the materials included in the compound product is preformed and loose-sintered from powder into a body of the desired shape.
  • the density during preforming and loose sintering preferably increases to a density of the loose-sintered body of 75-85% of the theoretical density (hereinafter abbreviated "T.D.") from an apparent density of the filled powder (hereinfafter referred to as "filling density") of 65-75% of T.D.
  • the preformed, loose-sintered body is thereafter placed, together with at least one additional powder material, in a capsule.
  • the capsule is sealed essentially gas-tightly and isostatically compressed into an essentially fully dense body with an essentially perfect metallic bond, atomic bond, between the materials included.
  • the capsule is removed and the product is after-treated in conventional manner by machining and heat treatment.
  • a body preformed according to the foregoing description is sintered according to the invention into a porous body; preferably the body is sintered at a temperature corresponding to 30 - 60% of the melting point of the material.
  • the purpose of the sintering is only to hold together the preformed body during the handling up to the point where it is placed in the capsule. At the same time, any organic binders used during the forming are driven off.
  • the sintering is preferably performed under vacuum or in a protective gas atmosphere to avoid reactions on the surfaces of the powder grains.
  • the temperature is chosen such that the powder grains are bonded together at the points of contact, only an insignificant increase of the density then being obtained.
  • the density during preforming and loose sintering increases from a filling density of 65-75% of T.D. to a density of the loose-sintered body of 75-85% of T.D.
  • the preformed body is sintered, according to the invention, when using spherical powder, for example obtained by gas atomisation of metal melts, into a porous body with a density of 75-80% starting from a filling density of about 70%.
  • At least one loose-sintered body is placed in a capsule together with at least one additional powder material.
  • the capsule which at least at the pressing temperature is deformable, is thereafter sealed essentially gas-tightly and is compacted by means of isostatic pressing, preferably hot-isostatic pressing, the compound product in its entirety being compacted into essentially full density, while at the same time the materials are bonded together with a metallic bond.
  • isostatic pressing preferably hot-isostatic pressing
  • Figure 1 illustrates the manufacture of compound products according to the invention and Figure 2 shows how the invention is applied when a diffuse transition is desired between the materials united in the compound product.
  • powdered material is formed at 1 and loose-sintered at 2 into a body 10, the density of which insignificantly exceeds the filling density of the used powder.
  • the loose-sintered body 1 may consist of only one powder material or be a composite of a plurality of powder materials.
  • the loose sintering at 2 takes place under inert conditions for the powder, preferably under vacuum or in a protective gas atmosphere, to avoid reactions on the surfaces of the powder grains.
  • the loose-sintered body 10 is placed in a capsule 11 which is filled, at 4, with at least one additional powder material before it is evacuated, at 5, and gas-tightly sealed, at 6.
  • the loose-sintered body 10 of course undergoes the usual steps such as checks and analyses of a quality-assuring nature, dimensional adjustments and other conventional operations before being placed in the capsule 11.
  • the compaction, at 7, preferably takes place in a hot-isostatic press.
  • the manufacture of a compound product 12, according to the invention comprises conventional operations in powdermetallurgical manufacture, carried out both on the loose-sintered body 10 and on the finished compound product 12, to ensure quality, dimensions, and material structure.
  • a transition zone between the materials included, where the interface between the materials is made diffuse may require a transition zone between the materials included, where the interface between the materials is made diffuse.
  • this is achieved by forming a body, in Figure 2 exemplified by the sleeve 100 which will be described below, with a diffuse transition from one of the materials A, in Figure 2 exemplified as a surface layer 101 on a compound roll 120, to the material B, which in Figure 2 constitutes the material in the core 105 of the roll.
  • the preformed sleeve 100 comprises the surface layer 101, consisting of the material A, and a transition zone 102 where the content of the material B is gradually increased to achieve a diffuse transition between the materials.
  • the sleeve is preformed according to the steps shown in Figure 1, that is, preforming 1 and loose sintering 2 whereupon the sleeve 100 consisting of the surface layer 101 and the transition zone 102 is placed in a capsule. Thereafter, at 4, the capsule is filled with material B in the form of a powder material. The capsule is evacuated, at 5, and gas-tightly sealed, at 6, before it is isostatically compacted, at 7, with preformed sleeve and powder material, into an essentially dense compound roll 120.
  • the compaction 7 is preferably performed in a hot-isostatic press.
  • the manufacture of a compound roll according to the invention, of course comprises conventional operations for powdermetallurgical manufacture, carried out on the loose-sintered sleeve 100 as well as on the finished compound roll 120, to assure quality, dimensions and material structure.
  • the invention is applicable, for example, to the manufacture of valve seats and valve cones in which parts exposed to wear are formed as loose-sintered bodies in hard wear-resistant materials, for example Co-based alloys, loose-sintered at 500-700°C in a vacuum furnace.
  • the loose-sintered body is then placed in a capsule made of steel plate, whereupon a powder of a high temperature material, such as a 12% Cr steel, is added.
  • the capsule is evacuated and sealed before being compacted, with its contents of porous loose-sintered bodies of a Co base alloy and a steel powder, by means of hot-isostatic pressing at a temperature of 1000-1250°C and a pressure of 50-300 MPa, into a valve cone or a valve seat.
  • the invention can be applied to the manufacture of compound rolls, in which case a relatively thick surface layer of a hard material is united with a tough core.
  • a porous loose-sintered sleeve is manufactured of the hard material.
  • the hard material constitutes only an outer shell, which is provided with an inner zone where the content of the tough material, which is to constitute the core material in the frame of the roll, is gradually increased to create a diffuse transition zone between the hard outer layer and the tough frame and hence considerably reduce the tendency to crack.
  • the porous sleeve is loose-sintered under the same conditions as the bodies in the manufacture of valve parts and, like these, is compacted with a steel powder in a steel plate capsule under equivalent conditions.
  • the loose sintering may take place in a protective gas furnace with Ar atmosphere at the same temperatures as above and the compaction take place using cold-isostatic pressing followed by sintering.
  • porous bodies are preformed and loose-sintered in a corrosion-resistant material, for example an Ni base alloy.
  • the porous bodies are placed in a capsule whereupon the capsule is filled with a powder, for example in the form of a tempering steel, evacuated, and gas-tightly sealed.
  • the capsule with its contents of at least one loose-sintered, porous body as well as steel powder is compacted into an essentially tight armature part by hot-isostatic pressing. Loose sintering and hot-isostatic pressing are carried out under conditions essentially equivalent to those described in previous examples.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Composite Materials (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Powder Metallurgy (AREA)

Abstract

Procédé de fabrication d'un produit composé à partir de matières en poudre, au moins une matière en poudre (10) étant préformée (1) et frittée sans compression (2) en un corps poreux et maniable d'une densité de 75-85 % de la Densité Théorique, partant d'une matière en poudre d'une densité de remplissage de 65-75 % de la Densité Théorique. Le corps préformé et fritté sans compression est placé (3) dans une capsule (11). La capsule est remplie (4) d'au moins une matière en poudre additionnelle, le vide y est créé (5), la capsule est hermétiquement refermée (6) de manière essentiellement étanche au gaz, et comprimée (7) par compression isostatique en un corps essentiellement dense (10), de préférence avec une liaison métallique ou une liaison atomique entre les matières incluses.

Claims (6)

  1. Un procédé de fabrication d'un produit composé à partir d'un matériau en poudre, dans lequel au moins un corps (10) est préformé (1) et fritté (2) pour donner un corps poreux pouvant être manipulé, et est placé (3) dans une capsule (11), et au moins un matériau en poudre supplémentaire est introduit (4) dans la capsule, la capsule avec le corps préformé et la poudre supplémentaire étant ensuite placée sous vide (5), fermée de manière étanche (6) et compactée (7) pour donner un corps solide, caractérisé en ce que le dit au moins un corps préformé (10), a été préformé pour donner un corps fritté de façon lâche ayant une densité de 75-85% de la densité théorique, D.T., à partir d'un matériau en poudre ayant une densité de remplissage de 65-75% de la D.T., et en ce que la capsule est compactée, par pressage isostatique, pour donner un corps (10) ayant pratiquement la densité maximale, avec une liaison métallique, c'est-à-dire une liaison atomique, entre les différents matériaux qui sont enfermés dans la capsule.
  2. Un procédé selon la revendication 1, caractérisé en ce que le corps (10) est préformé et fritté de façon lâche (2) pour donner un corps poreux ayant une densité après le frittage lâche de 75-80%, en partant d'une poudre de métal atomisée par gaz, de forme sphérique, ayant une densité de remplissage d'environ 70%.
  3. Un procédé selon la revendication 1 ou 2, caractérisé en ce que le corps (10) est fritté de façon lâche (2) à une température correspondant à 40-60% de la température de fusion du matériau en poudre considéré, de préférence dans un four à vide ou à gaz protecteur.
  4. Un procédé selon l'une quelconque des revendications précédentes, caractérisé en ce que le corps fritté préformé (10) est formé (1) à partir d'au moins deux matériaux en poudre.
  5. Un procédé selon la revendication 4, caractérisé en ce que les matériaux en poudre dans le corps fritté préformé (10) sont mélangés de façon à obtenir une transition continue, sans démarcation entre les matériaux en poudre.
  6. Un procédé selon l'une quelconque des revendications précédentes, caractérisé en ce que la capsule contenant le corps fritté préformé (10) et un matériau en poudre est compactée (7) par pressage isostatique à chaud à une température comprise entre 1000 et 1250°C et une pression comprise entre 50 et 300 MPa.
EP91910811A 1990-06-11 1991-05-30 Procede de fabrication de produits composes Expired - Lifetime EP0533745B1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
SE9002075A SE468378B (sv) 1990-06-11 1990-06-11 Saett att tillverka en kompoundkropp
SE9002075 1990-06-11
PCT/SE1991/000382 WO1991019583A1 (fr) 1990-06-11 1991-05-30 Procede de fabrication de produits composes

Publications (2)

Publication Number Publication Date
EP0533745A1 EP0533745A1 (fr) 1993-03-31
EP0533745B1 true EP0533745B1 (fr) 1996-03-27

Family

ID=20379733

Family Applications (1)

Application Number Title Priority Date Filing Date
EP91910811A Expired - Lifetime EP0533745B1 (fr) 1990-06-11 1991-05-30 Procede de fabrication de produits composes

Country Status (4)

Country Link
EP (1) EP0533745B1 (fr)
DE (1) DE69118379T2 (fr)
SE (1) SE468378B (fr)
WO (1) WO1991019583A1 (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB9500503D0 (en) * 1995-01-11 1995-03-01 Saveker Jonathan J High speed cutting tool

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2970905A (en) * 1957-09-18 1961-02-07 Haller Inc Method of making a composite sintered powdered material article
DE2262400C3 (de) * 1972-12-15 1975-05-07 Mannesmann Ag, 4000 Duesseldorf Verfahren zum Herstellen von mehrschichtigen Formkörpern mit vollem oder hohlem Querschnitt
SE8306717L (sv) * 1983-12-06 1985-06-07 Bjorn Aren Sett att framstella ett for bearbetning, exempelvis formande och/eller skerande bearbetning, av ett materiel avsett verktyg samt ett, foretredesvis medelst settet framstellt, verktyg
IT1211284B (it) * 1987-09-03 1989-10-12 Iveco Fiat Procedimento per la realizzazione di pezzi meccanici dotati di un rivestimento antiusura e o anticorrosione

Also Published As

Publication number Publication date
SE468378B (sv) 1993-01-11
DE69118379T2 (de) 1996-11-07
SE9002075D0 (sv) 1990-06-11
EP0533745A1 (fr) 1993-03-31
WO1991019583A1 (fr) 1991-12-26
DE69118379D1 (de) 1996-05-02
SE9002075L (sv) 1991-12-12

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