EP0005285B1 - Process for applying a dense layer of cermets or cemented carbides to a metal object - Google Patents

Process for applying a dense layer of cermets or cemented carbides to a metal object Download PDF

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Publication number
EP0005285B1
EP0005285B1 EP79200170A EP79200170A EP0005285B1 EP 0005285 B1 EP0005285 B1 EP 0005285B1 EP 79200170 A EP79200170 A EP 79200170A EP 79200170 A EP79200170 A EP 79200170A EP 0005285 B1 EP0005285 B1 EP 0005285B1
Authority
EP
European Patent Office
Prior art keywords
layer
sprayed
cermets
metal
pressure
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
Application number
EP79200170A
Other languages
German (de)
French (fr)
Other versions
EP0005285A1 (en
Inventor
Hans Bertil Van Nederveen
Martin Bastiaan Verburgh
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.)
SKF Industrial Trading and Development Co BV
Original Assignee
SKF Industrial Trading and Development Co BV
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 SKF Industrial Trading and Development Co BV filed Critical SKF Industrial Trading and Development Co BV
Publication of EP0005285A1 publication Critical patent/EP0005285A1/en
Application granted granted Critical
Publication of EP0005285B1 publication Critical patent/EP0005285B1/en
Expired legal-status Critical Current

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    • 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
    • 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
    • C23C4/04—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge characterised by the coating material
    • C23C4/06—Metallic material

Definitions

  • the invention relates to a process for applying a dense, hard and wear-resistant layer of cermets or cemented carbides to a metal object by spraying a powder material consisting of hard particles of cermets or cemented carbides, followed by consolidation of the sprayed-on layer at high temperature and pressure.
  • British patent specification 1.451.113 discloses a process for spraying a layer on a metal object, such layer consisting of a metal or an alloy, which may contain ceramic materials (so-called cermets).
  • cermets ceramic materials
  • spraying by known methods, for example flame spraying or plasma spraying of powdered materials, a porous layer is obtained.
  • the adhesion of this layer to the base material is found unsatisfactory, and therefore the said patent specification recommends consolidating the porous layer by fusing the binder metal present therein under vacuum, thus reducing the porosity. To combat oxidation, this fusion is carried out under vacuum.
  • good results are obtained by this method if the layer consists of 50 percent by weight of tungsten carbide in a matrix of a nickel-chromium alloy serving as binder metal.
  • binder metal in the layer decreases, and the content of hard particles accordingly increases, it seems to become more and more difficult to consolidate the layer by fusing the binder metal, and at a binder metal content of 30 percent or less, it becomes practically impossible.
  • DE - A - 1.783.061 proposes application of a comparable dense layer by built-up welding, using a tubular or rod welding electrode containing a binder metal and tungsten carbides.
  • a tubular or rod welding electrode containing a binder metal and tungsten carbides.
  • Such an electrode preferably contains 30-40 percent by weight of binder metal and 70-60 percent by weight of carbide particles. During welding, this material is further mingled with some quantity of molten base material.
  • the binder metal must contain at least one of the metals Co, Ni, Fe or Cr as chief constituent.
  • the layer consists of more than 70 percent by weight of ceramic particles, such as hard metal carbides, for example tungsten or titanium carbide, or other hard materials.
  • ceramic particles such as hard metal carbides, for example tungsten or titanium carbide, or other hard materials.
  • a cohesive and/or adhesive bond cannot be improved by internal fusion.
  • the consolidation of the sprayed-on porous layer is accomplished by isostatic compaction at a temperature of at least 1000°C and a pressure of at least 1000 bars, for at least one half hour, whereby said binder metal is not melted.
  • British Patent specification 1.367.762 discloses a method to form a sprayed-on cermet coating on a surface of a thin metal sheet whereby both coating and substrate are subjected to hot pressing or sintering. According to this method pressing is executed from one side or opposite sides of the metal sheet; therefore this method is not suitable when more, e.g. rounded sides of a body have to be processed with improved layers in one step.
  • the process according the invention is especially suitable for applying a layer of tungsten carbide/cobalt to a forged, cast or sintered core or similar base material
  • Cermets or other metals or ceramic materials may alternatively be used, for example TiC or Si 2 N 4 .
  • binder metal a metal or an alloy consisting predominantly of Ni, Co, Fe or Cr may be used.
  • cobalt or an a!!oy of cobalt and nickel is used. The proper choice of course depends partly on the base material used, to which the applied layer must bond well.
  • the layer is applied by spraying on of a powder mixture containing the binder metal and the particles in the desired proportion for the layer.
  • This spraying may be carried out in conventional manner, for example by flame spraying or plasma spraying, a porous layer being formed in either case.
  • the objects may be completely or only partly coated with the sprayed layer.
  • the coating material may be applied in one or several steps. If desired, the successive layers may differ from each other in composition.
  • the surface may then be finished smooth. In most cases, however, this can be omitted because the roughness of the surface after consolidation is chiefly determined by the grain size of the pressure transmitting medium. If the proper grain size is used, the smoothness of the surface will be sufficient in most cases even without finishing. A grain size of 0.10-0.25 mm is very satisfactory for many purposes.
  • a mixture containing at least 7 percent by weight of cermet particles is used for the sprayed-on layer, and preferably a mixture consisting of 83-94 percent by weight of tungsten carbide, remainder cobalt.
  • the thermal expension coefficients of cermets or cemented carbides differ appreciably from those of metals.
  • FIG. 1 schematically representing an object produced according to the invention
  • Fig. 2 and 3 showing photographs of a compacted layer before and after the hot isostatic compaction.
  • the coated object 3 is placed in a comparatively thin-walled holder 2, for example of low-alloy steel. Then the holder is completely filled with a pressure transmitting medium 5 and closed gastight with a cover 1. Then the holder 2 is placed in a hot isostatic press (not shown) in which the holder is heated to the consolidating temperature, which is at least 1000°C, preferably 1000-1400°C. The temperature during this operation is always such that the consolidation takes place in the solid phase. At this temperature the binder metal does not melt, but some sintering does occur. Simultaneously with the raising of the temperature, or after the desired temperature has been reached, the gas pressure in the press is raised to at least 1000 bars, preferably up to 1800 bars.
  • Fig. 2 shows a photograph of a plasma- sprayed layer 4A on a base material 3A before hot isostatic compaction.
  • Fig. 3 is a photograph taken after hot isostatic compaction and shows that 1) layer 4 has attained maximum density, 2) an optimum diffusion bond 6 has been formed between 3 and 4.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Plasma & Fusion (AREA)
  • Physics & Mathematics (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Coating By Spraying Or Casting (AREA)
  • Other Surface Treatments For Metallic Materials (AREA)
  • Powder Metallurgy (AREA)
  • Ceramic Capacitors (AREA)

Description

  • The invention relates to a process for applying a dense, hard and wear-resistant layer of cermets or cemented carbides to a metal object by spraying a powder material consisting of hard particles of cermets or cemented carbides, followed by consolidation of the sprayed-on layer at high temperature and pressure.
  • British patent specification 1.451.113 discloses a process for spraying a layer on a metal object, such layer consisting of a metal or an alloy, which may contain ceramic materials (so-called cermets). In spraying by known methods, for example flame spraying or plasma spraying of powdered materials, a porous layer is obtained. In many cases, the adhesion of this layer to the base material is found unsatisfactory, and therefore the said patent specification recommends consolidating the porous layer by fusing the binder metal present therein under vacuum, thus reducing the porosity. To combat oxidation, this fusion is carried out under vacuum. According to the said patent specification, good results are obtained by this method if the layer consists of 50 percent by weight of tungsten carbide in a matrix of a nickel-chromium alloy serving as binder metal.
  • As the content of binder metal in the layer decreases, and the content of hard particles accordingly increases, it seems to become more and more difficult to consolidate the layer by fusing the binder metal, and at a binder metal content of 30 percent or less, it becomes practically impossible.
  • DE - A - 1.783.061 proposes application of a comparable dense layer by built-up welding, using a tubular or rod welding electrode containing a binder metal and tungsten carbides. Such an electrode, according to the specification, preferably contains 30-40 percent by weight of binder metal and 70-60 percent by weight of carbide particles. During welding, this material is further mingled with some quantity of molten base material. According to DE - A - 1 783 061, the binder metal must contain at least one of the metals Co, Ni, Fe or Cr as chief constituent.
  • By this method also, it is not possible to apply a dense layer to a metal object in such a way that the layer consists of more than 70 percent by weight of ceramic particles, such as hard metal carbides, for example tungsten or titanium carbide, or other hard materials. In a layer with so high a content of hard particles, a cohesive and/or adhesive bond cannot be improved by internal fusion.
  • According to the invention, in a process of the type initially referred to, the consolidation of the sprayed-on porous layer is accomplished by isostatic compaction at a temperature of at least 1000°C and a pressure of at least 1000 bars, for at least one half hour, whereby said binder metal is not melted.
  • In this way, i.e. at a specific isostatic pressure process, it is possible to obtain an applied layer of high density and markedly improved bonding to the base material, which can have a complicated shape. British Patent specification 1.367.762 discloses a method to form a sprayed-on cermet coating on a surface of a thin metal sheet whereby both coating and substrate are subjected to hot pressing or sintering. According to this method pressing is executed from one side or opposite sides of the metal sheet; therefore this method is not suitable when more, e.g. rounded sides of a body have to be processed with improved layers in one step.
  • The process according the invention is especially suitable for applying a layer of tungsten carbide/cobalt to a forged, cast or sintered core or similar base material Cermets or other metals or ceramic materials may alternatively be used, for example TiC or Si2N4. As binder metal, a metal or an alloy consisting predominantly of Ni, Co, Fe or Cr may be used. Preferably cobalt or an a!!oy of cobalt and nickel (Co/Nil is used. The proper choice of course depends partly on the base material used, to which the applied layer must bond well.
  • The layer is applied by spraying on of a powder mixture containing the binder metal and the particles in the desired proportion for the layer. This spraying may be carried out in conventional manner, for example by flame spraying or plasma spraying, a porous layer being formed in either case. The objects may be completely or only partly coated with the sprayed layer. Depending on the desired thickness of layer, the coating material may be applied in one or several steps. If desired, the successive layers may differ from each other in composition.
  • If necessary, the surface may then be finished smooth. In most cases, however, this can be omitted because the roughness of the surface after consolidation is chiefly determined by the grain size of the pressure transmitting medium. If the proper grain size is used, the smoothness of the surface will be sufficient in most cases even without finishing. A grain size of 0.10-0.25 mm is very satisfactory for many purposes.
  • According to a preferred form of the invention, a mixture containing at least 7 percent by weight of cermet particles is used for the sprayed-on layer, and preferably a mixture consisting of 83-94 percent by weight of tungsten carbide, remainder cobalt.
  • The thermal expension coefficients of cermets or cemented carbides differ appreciably from those of metals. To prevent the applied layers from cracking loose as a result of thermal stresses during cooling at the end of the consolidating operation, it is preferable to vary the content of cermets or ceramic materials in the direction of depth by applying the coating layer in two or more steps, the content of binder metal being varied from one sprayed-on layer to another.
  • The invention will now be further illustrated with reference to figures.
  • Fig. 1 schematically representing an object produced according to the invention, and Fig. 2 and 3 showing photographs of a compacted layer before and after the hot isostatic compaction.
  • After spraying on of the layer 4, the coated object 3 is placed in a comparatively thin-walled holder 2, for example of low-alloy steel. Then the holder is completely filled with a pressure transmitting medium 5 and closed gastight with a cover 1. Then the holder 2 is placed in a hot isostatic press (not shown) in which the holder is heated to the consolidating temperature, which is at least 1000°C, preferably 1000-1400°C. The temperature during this operation is always such that the consolidation takes place in the solid phase. At this temperature the binder metal does not melt, but some sintering does occur. Simultaneously with the raising of the temperature, or after the desired temperature has been reached, the gas pressure in the press is raised to at least 1000 bars, preferably up to 1800 bars. This diminishes the volume of the holder 2, and the gas pressure is transmitted by way of the pressure transmitting medium 5 to the object 3 with sprayed-on layer 4. Under the influence of this temperature and pressure, the layer 4 is consolidated, while at the same time a diffusion is formed with the base material 3. This process takes at least one half-hour, counting from attainment of the consolidation temperature to the commencement of the cooling. Preferably the operation is continued for 1/2 to 2 hours. Then the temperature and pressure are allowed to return to normal, after which the object is removed from the holder 2.
  • Fig. 2 shows a photograph of a plasma- sprayed layer 4A on a base material 3A before hot isostatic compaction.
  • Fig. 3 is a photograph taken after hot isostatic compaction and shows that 1) layer 4 has attained maximum density, 2) an optimum diffusion bond 6 has been formed between 3 and 4.

Claims (6)

1. Process for applying a dense, hard and wear-resistant layer of cermets or cemented carbides to a metal object by spraying a powder material consisting of hard particles of cermets or cemented carbides followed by consolidation of the sprayed-on layer at high temperature and pressure, characterized in that the sprayed-on layer is consolidated by isostatic compacting at a temperature of at least 1000°C and a pressure of at least 1000 bars for at least 1/2 hour, whereby the binder metal is not melted.
2. Process according to claim 1, characterized in that a mixture containing at least 70 percent by weight of ceramic particles, is used for the sprayed-on layer.
3. Process according to claim 1 or 2, characterized in that the sprayed-on layer contains 83-94 percent by weight of tungsten carbide, remainder cobalt.
4. Process according to claim 3, characterized in that the consolidation is carried out during a period of 1/2 to 2 hours at a temperature of 1000-14000C and a pressure of 1000-1800 bars.
5. Process according to claims 1 to 4, characterized in that the coating layer is applied in two or more steps, the content of binder metal in the sprayed-on layers being so varied as to prevent the layers from cracking loose because of differences in coefficient of expansion.
6. Metal objects completely or partially coated with a dense layer obtained according to one of the preceding claims.
EP79200170A 1978-04-26 1979-04-09 Process for applying a dense layer of cermets or cemented carbides to a metal object Expired EP0005285B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NL7804454A NL7804454A (en) 1978-04-26 1978-04-26 METHOD OF APPLYING A DENSE LAYER OF CERAMIC METAL OR CERMETS ON A METAL ARTICLE
NL7804454 1978-04-26

Publications (2)

Publication Number Publication Date
EP0005285A1 EP0005285A1 (en) 1979-11-14
EP0005285B1 true EP0005285B1 (en) 1982-03-17

Family

ID=19830731

Family Applications (1)

Application Number Title Priority Date Filing Date
EP79200170A Expired EP0005285B1 (en) 1978-04-26 1979-04-09 Process for applying a dense layer of cermets or cemented carbides to a metal object

Country Status (9)

Country Link
EP (1) EP0005285B1 (en)
JP (1) JPS54142220A (en)
AU (1) AU528527B2 (en)
CA (1) CA1124586A (en)
DE (1) DE2962269D1 (en)
MX (1) MX151789A (en)
NL (1) NL7804454A (en)
NO (1) NO153694C (en)
ZA (1) ZA791582B (en)

Families Citing this family (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL7905973A (en) * 1979-08-03 1981-02-05 Skf Ind Trading & Dev METHOD FOR APPLYING A DENSE, HARD, TIGHT AND WEAR-RESISTANT COAT OF CERMETS OR CERAMIC MATERIAL ON A METAL ARTICLE AND OBTAINED THEREFORE.
NL7908745A (en) * 1979-12-04 1981-07-01 Skf Ind Trading & Dev METHOD FOR MANUFACTURING AN ARTICLE APPLIED BY THERMAL SPRAYING AND OBJECT, IN PARTICULAR A DRILLING CHISEL, OBTAINED BY THIS METHOD
JPS60215754A (en) * 1984-04-11 1985-10-29 Nippon Kokan Kk <Nkk> Manufacture of thermally sprayed layer having high hardness
US4996119A (en) * 1984-08-27 1991-02-26 Kabushiki Kaisha Kenwood Speaker cone plate and method of forming
JPS61257402A (en) * 1984-12-25 1986-11-14 Namekawa Tatsuo Method for molding inside surface of irregular shaped hollow metallic article
US4603062A (en) * 1985-01-07 1986-07-29 Cdp, Ltd. Pump liners and a method of cladding the same
JPS61201786A (en) * 1985-03-04 1986-09-06 Nippon Telegr & Teleph Corp <Ntt> Surface treatment of material
JPH0778273B2 (en) * 1987-11-27 1995-08-23 トーカロ株式会社 Wing member surface treatment method
DE3814362C1 (en) * 1988-04-28 1989-12-07 Thyssen Guss Ag, 4330 Muelheim, De Process for producing bucket tappets and similarly stressed components in internal combustion engines
US4978487A (en) * 1989-01-13 1990-12-18 Westinghouse Electric Corp. Method of treating a coating on a reactor coolant pump sealing surface
US5057340A (en) * 1990-04-20 1991-10-15 Westinghouse Electric Corp. Method of forming a coating on a reactor coolant pump sealing surface
EP0459637B1 (en) * 1990-05-10 1994-12-07 Apv Corporation Limited Process for applying a coating to a metal or ceramic object
US7043819B1 (en) * 1996-12-23 2006-05-16 Recast Airfoil Group Methods for forming metal parts having superior surface characteristics
WO1999023272A1 (en) * 1997-11-03 1999-05-14 Siemens Aktiengesellschaft Method for producing a protective coating on a base body intended to be impinged upon by a hot gas and corresponding product
CN103143699B (en) * 2013-03-07 2015-03-11 南通高欣金属陶瓷复合材料有限公司 Composite reinforced wear-resistant part of metal-ceramic prefabricated member and manufacturing method of composite reinforced wear-resistant part

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1434158A (en) * 1964-11-25 1966-04-08 Sfec Improvements to refractory protective coatings, and method of manufacturing these elements
NL6709916A (en) * 1967-07-17 1968-11-25
GB1367762A (en) * 1971-09-17 1974-09-25 Ass Eng Ltd cermet materials

Also Published As

Publication number Publication date
EP0005285A1 (en) 1979-11-14
NO791368L (en) 1979-10-29
DE2962269D1 (en) 1982-04-15
NO153694C (en) 1986-05-07
NO153694B (en) 1986-01-27
CA1124586A (en) 1982-06-01
JPS54142220A (en) 1979-11-06
AU4589179A (en) 1979-11-29
AU528527B2 (en) 1983-05-05
NL7804454A (en) 1979-10-30
ZA791582B (en) 1980-04-30
JPS636630B2 (en) 1988-02-10
MX151789A (en) 1985-03-18

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