EP0305746A1 - Procédé pour la fabrication de pièces mécaniques pourvues d'un revêtement résistant à l'abrasion et à l'érosion - Google Patents

Procédé pour la fabrication de pièces mécaniques pourvues d'un revêtement résistant à l'abrasion et à l'érosion Download PDF

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Publication number
EP0305746A1
EP0305746A1 EP88112432A EP88112432A EP0305746A1 EP 0305746 A1 EP0305746 A1 EP 0305746A1 EP 88112432 A EP88112432 A EP 88112432A EP 88112432 A EP88112432 A EP 88112432A EP 0305746 A1 EP0305746 A1 EP 0305746A1
Authority
EP
European Patent Office
Prior art keywords
coating
wear
sintering
corrosion
resistant coating
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.)
Granted
Application number
EP88112432A
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German (de)
English (en)
Other versions
EP0305746B1 (fr
Inventor
Sante Quaranta
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.)
Iveco SpA
Original Assignee
Iveco Fiat SpA
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Iveco Fiat SpA filed Critical Iveco Fiat SpA
Publication of EP0305746A1 publication Critical patent/EP0305746A1/fr
Application granted granted Critical
Publication of EP0305746B1 publication Critical patent/EP0305746B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
    • C23C4/18—After-treatment
    • 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
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/12—Both compacting and sintering
    • B22F3/1208—Containers or coating used therefor
    • B22F3/1258—Container manufacturing
    • B22F3/1266—Container manufacturing by coating or sealing the surface of the preformed article, e.g. by melting

Definitions

  • the present invention relates to a method for the production of components having a wear- and/or corrosion-resistant coating.
  • the present invention relates to a method for the coating of products required to withstand high hammering, rolling and frictional stresses with or without corrosion due to external agents, both cold and hot, with materials which have high wear resistance.
  • products for example, tappets, cams, eccentrics, dies, etc.
  • tappets, cams, eccentrics, dies, etc. are normally consituted by a metal body which is not particularly resistant to wear and/or corrosion, in which the most stressed portion is covered with a coating of more expensive material selected in dependence on the type of stress and/or corrosive environment to which the product in question will be subject.
  • the coating of the metal substrates with friction- and/or corrosion-resistant materials is carried out hot, for example, by the techniques of deferred-arc plasma, laser-beam melting bond, spray coating by means of plasma, etc.
  • the material of the coating is stressed by considerable residual internal tensile forces as it cools and these persist in the finished product. These forces arise since the substrate, through the forces due to the adhesion between the substrate and the coating material, prevents the latter from shrinking freely from the temperature used for the coating to the ambient temperature.
  • the object of the present invention is to provide a method of the type specified at the begin­ning of the description, which does not have the above disadvantages and which enables full use to be made of the advantages of the hot application of a wear- and/or corrosion-resistant coating to products of low-cost base materials.
  • this object is achieved by virtue of the fact that the method in­cludes the steps of forming a component by the com­pression of powders, applying the coating to the component, said coating having a melting point higher than the sintering temperature of the component, and subjecting the coated component to sintering.
  • the component is subjected to a pre-sintering treatment before the application of the coating.
  • a green is indicated 10 and, after the sintering process, is intended to constitute a tappet element of an internal combustion engine, comprising a shaft 11 and a flat 13 provided with a working surface 12.
  • the green 10 may, for example, be made of sintered low-alloy steel corresponding, for example, to a conventional C10. After formation of the green 10, achieved by cold compression in a die, it may be introduced into a pre-sintering furnace (not illustrated), both in order to obtain a more easily handled product and in order to be able to control the dimensional shrinkage, shown in the drawings by broken lines R.
  • a pre-sintered part 14 which has characteristics of strength such as to enable it to proceed without problems to the subsequent stage of coating of the working surface 12 with a layer 16 of coating material having a melting point higher than the sintering temperature of the green and having high wear- and/or corrosion-resist­ance.
  • the layer 16 is constituted by powders de­posited at high temperature by various techniques (deferred-arc plasma, laser melting bond, plasma spray etc.).
  • the hot application of the coating 16 means that, as it bonds to the pre-sintered part 14 which is at a lower temperature, the coating is subjected during cooling to internal tensile stresses which persist after cooling.
  • the next stage involves the passage of the pre-sintered part 14, with the layer of coating 16, into a sintering furnace in which the pre­sintered part 14 is transformed, at a high tempera­ ture, and for a time from 1 to 3 hours into a sintered part 18 with a further change in dimensions.
  • This change means that the layer of coating 16 of the pre-sintered part 14 is transformed into a layer 16′ in which the tensile stress condition is can­celled out or transformed into a compressive stress condition which, in the specific case of a tappet with a flat, is particularly suitable for the type of stress to which the product will be subjected in use (impact, rolling and sliding stress from the cam acting on the tappet).
  • any stress condition between the coating 16′ and the sintered part 18 may be convenient to eliminate any stress condition between the coating 16′ and the sintered part 18, or it may be opportune to maintain a condition of slight tensile stress so that any problems of thermal stress can be resolved without disadvantages to the part.
  • This "piloting" of the stress condition of the coating layer 16′ may be obtained by a suit­able selection of the particle size and elements of the pow­ders used to produce the green 10, defined in dependence on the reduction in volume which is to be obtained as a result of the self-densification undergone by the product in the sintering process.
  • Another variable on which it is possible to act to produce the desired stress condition in the coating 16′ is the duration of the initial pre-sintering stage.
  • the method may be carried out by coating the green 10 directly, without its passing through the pre-sintering stage.
  • the adhesion between substrate and coating layer is achieved by the cold compression in a die of a green formed by a main body of low cost metallic powders and by a coating portion of powder material having high wear- and/or corrosion resistance.
  • the material of the coating portion must have a melting point higher than the sintering temperature of the main body. The main body and the coating portion are then sintered with the same thermal cycle, or by means of liquid phase sintering.
  • the main body is subjected to a reduction in volume which is higher than that of the coating portion, allowing to stop the process when a desired stress condition is obtained between the sintered body and the sintered coating portion.
  • the method according to the invention has advan­tages for the sintering of ceramic powders or metal-­ceramic powder mixtures too.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Plasma & Fusion (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Materials Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Other Surface Treatments For Metallic Materials (AREA)
  • Powder Metallurgy (AREA)
  • Compositions Of Oxide Ceramics (AREA)
EP88112432A 1987-09-03 1988-08-01 Procédé pour la fabrication de pièces mécaniques pourvues d'un revêtement résistant à l'abrasion et à l'érosion Expired - Lifetime EP0305746B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IT6775487 1987-09-03
IT8767754A IT1211284B (it) 1987-09-03 1987-09-03 Procedimento per la realizzazione di pezzi meccanici dotati di un rivestimento antiusura e o anticorrosione

Publications (2)

Publication Number Publication Date
EP0305746A1 true EP0305746A1 (fr) 1989-03-08
EP0305746B1 EP0305746B1 (fr) 1993-10-13

Family

ID=11305030

Family Applications (1)

Application Number Title Priority Date Filing Date
EP88112432A Expired - Lifetime EP0305746B1 (fr) 1987-09-03 1988-08-01 Procédé pour la fabrication de pièces mécaniques pourvues d'un revêtement résistant à l'abrasion et à l'érosion

Country Status (4)

Country Link
EP (1) EP0305746B1 (fr)
DE (1) DE3884894T2 (fr)
ES (1) ES2045035T3 (fr)
IT (1) IT1211284B (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1991019583A1 (fr) * 1990-06-11 1991-12-26 Asea Brown Boveri Ab Procede de fabrication de produits composes
WO1999023272A1 (fr) * 1997-11-03 1999-05-14 Siemens Aktiengesellschaft Procede de realisation d'une couche de protection sur un corps de base conçu pour etre soumis a l'action d'un gaz chaud, et produit ainsi conçu

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2350404A1 (fr) * 1976-05-07 1977-12-02 Maschf Augsburg Nuernberg Ag Procede de traitement thermique de pieces en matieres refractaires, notamment d'ailettes de turbines a gaz
US4339271A (en) * 1971-03-15 1982-07-13 Asea Ab Method of manufacturing a sintered powder body

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2620192C3 (de) * 1976-05-07 1981-03-19 Still Gmbh, 2000 Hamburg Schalter, insbesondere Fahrtrichtungsschalter für Flurförderzeuge mit elektrischem Antrieb

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4339271A (en) * 1971-03-15 1982-07-13 Asea Ab Method of manufacturing a sintered powder body
FR2350404A1 (fr) * 1976-05-07 1977-12-02 Maschf Augsburg Nuernberg Ag Procede de traitement thermique de pieces en matieres refractaires, notamment d'ailettes de turbines a gaz

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN, vol. 10, no. 362 (C-389)[2419], 4th December 1986; & JP-A-61 159 566 (DAIDO STEEL CO., LTD) 19-07-1986 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1991019583A1 (fr) * 1990-06-11 1991-12-26 Asea Brown Boveri Ab Procede de fabrication de produits composes
WO1999023272A1 (fr) * 1997-11-03 1999-05-14 Siemens Aktiengesellschaft Procede de realisation d'une couche de protection sur un corps de base conçu pour etre soumis a l'action d'un gaz chaud, et produit ainsi conçu

Also Published As

Publication number Publication date
IT1211284B (it) 1989-10-12
DE3884894T2 (de) 1994-02-10
DE3884894D1 (de) 1993-11-18
IT8767754A0 (it) 1987-09-03
ES2045035T3 (es) 1994-01-16
EP0305746B1 (fr) 1993-10-13

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