EP0257319B1 - Method of producing protective coatings - Google Patents

Method of producing protective coatings Download PDF

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Publication number
EP0257319B1
EP0257319B1 EP87110805A EP87110805A EP0257319B1 EP 0257319 B1 EP0257319 B1 EP 0257319B1 EP 87110805 A EP87110805 A EP 87110805A EP 87110805 A EP87110805 A EP 87110805A EP 0257319 B1 EP0257319 B1 EP 0257319B1
Authority
EP
European Patent Office
Prior art keywords
suspension
component
temperature
solvent
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.)
Expired - Lifetime
Application number
EP87110805A
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German (de)
French (fr)
Other versions
EP0257319A1 (en
Inventor
Werner Dr. Hüther
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.)
MTU Aero Engines GmbH
Original Assignee
MTU Motoren und Turbinen Union Muenchen GmbH
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.)
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Publication of EP0257319A1 publication Critical patent/EP0257319A1/en
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Anticipated expiration legal-status Critical
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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
    • C23C24/00—Coating starting from inorganic powder

Definitions

  • the invention relates to a method for producing protective layers against thermal and / or chemical and / or mechanical stresses on components, in particular on complexly shaped components, such as turbine blades.
  • a method for applying a coating layer to a shaped body in which the components of the coating layer to be formed are applied and baked onto the shaped body in an aqueous suspension by dipping, spraying or brushing.
  • a disadvantage of application by means of dipping is that the coating thickness is dependent on gravity and thus on the angle of inclination of the surface to be coated, which can lead to agglomeration of coating material on the one hand and to thinning out of the suspension on the other hand if the surface shape of the moldings is complicated.
  • Spraying and coating methods have the disadvantage that a sufficiently uniform layer thickness can be applied to the component only with great difficulty in the case of components of complex shape. The partial elimination of these difficulties is associated with considerable effort.
  • the object of the invention is to provide components or layered composite bodies with a protected surface, on parts already subjected to a shaping, in particular parts of complex shape, and to be able to cover them in a uniform layer thickness without great effort.
  • any desired layer thickness can be produced uniformly with the invention, and individual steps of the method can be repeated as often as desired, e.g. the production of the diving cover.
  • a heat treatment and other treatments of the coated component can be carried out after the production of the coating, such as e.g. sealing sintering or sealing on the surface.
  • a sintering or pressing program can also be combined for special requirements (hot isostatic pressing).
  • Energy beam treatments of the surface, doping, infiltration of substances other than layer material and in a form other than powder can also be used within the scope of the present invention.
  • a binder can advantageously be dissolved in the suspension liquid, which brings about an increased green strength of the powder layer if a powder is used as the layer material, the average grain size of which is above 25 ⁇ m. The organic binder is removed again at the beginning of the sintering process or in a separate heat treatment.
  • the invention is preferably used for protective layers, and here in particular for those which are subject to combined requirements.
  • the main area of application is general mechanical engineering, components for vehicles of all kinds, but also stationary systems such as manufacturing systems, especially apparatus engineering.
  • the base body of the composite body to be counted as the end product of the invention can be selected from almost any materials, such as metallic materials, metal compounds, intermetallic phases, ceramics, metal ceramics, metal glass, glass ceramics and / or combinations of the above. Fabrics with plastics.
  • substances or combinations of materials known per se can be selected as protective layers.
  • the percentages of the constituents for the starting materials or mixtures or suspensions given in the examples can be changed within wide limits.
  • the devices which are necessary for carrying out the method according to the invention are of a simple and customary type, in particular as regards the containers required for the immersion method or the coolants for the component, such as refrigerators.
  • the freeze dryers commonly used in food technology can be used for freeze drying, and the annealing and sintering ovens or presses or other post-treatment devices are also known per se.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Turbine Rotor Nozzle Sealing (AREA)
  • Other Surface Treatments For Metallic Materials (AREA)
  • Powder Metallurgy (AREA)

Abstract

1. A method of producing protective coatings against thermal and/or chemical and/or mechanical stresses on components, particularly components of complicated shape such as turbine blades, and in which the following steps are carried out : a) a powder of a starting material for the coating is brought into suspension with a solvent, b) the suspension is held ready at a temperature just above the freezing point of the solvent, c) the component to be coated is held ready at a temperature below the freezing point of the solvent d) the component is dipped into the suspension and a coating of the starting powder present in the suspension freezes solid, its thickness depending on the temperature of the component and the duration of immersion of the component in the bath of suspension, e) coated with the coating material, the component is exposed to a freeze drying process and until the freeze drying process is concluded, it is not heated to a temperature above the freezing point of the solvent.

Description

Die Erfindung betrifft ein Verfahren zum Herstellen von Schutzschichten gegen thermisch und/oder chemische und/oder mechanische Beanspruchungen von Bauteilen, insbesondere auf kompliziert geformten Bauteilen, wie Turbinenschaufeln.The invention relates to a method for producing protective layers against thermal and / or chemical and / or mechanical stresses on components, in particular on complexly shaped components, such as turbine blades.

Aus der Patentschrift FR-A 1 428 311 ist ein Verfahren zur Aufbringung einer Überzugsschicht auf einen Formkörper bekannt, bei der die Bestandteile der zu bildenden Überzugsschicht in einer wäßrigen Suspension durch Tauchen, Spritzen oder Streichen auf den Formkörper aufgebracht und eingebrannt werden. Ein Nachteil der Aufbringung mittels Tauchen besteht darin, daß die Beschichtungsdicke schwerkraftabhängig und damit vom Neigungswinkel der zu beschichtenden Oberfläche abhängig ist, was bei komplizierter Oberflächengestalt der Formteile zur Agglomeration von Beschichtungsmaterial einerseits und zur Ausdünnung der Suspension andererseits führen kann.From the patent FR-A 1 428 311 a method for applying a coating layer to a shaped body is known, in which the components of the coating layer to be formed are applied and baked onto the shaped body in an aqueous suspension by dipping, spraying or brushing. A disadvantage of application by means of dipping is that the coating thickness is dependent on gravity and thus on the angle of inclination of the surface to be coated, which can lead to agglomeration of coating material on the one hand and to thinning out of the suspension on the other hand if the surface shape of the moldings is complicated.

Spritz- und Streichverfahren haben den Nachteil, daß bei kompliziert geformten Bauteilen eine ausreichend gleichmäßige Schichtdicke auf dem Bauteil nur mit großen Schwierigkeiten aufgebracht werden kann. Die teilweise Beseitigung dieser Schwierigkeiten ist mit erheblichem Aufwand verbunden.Spraying and coating methods have the disadvantage that a sufficiently uniform layer thickness can be applied to the component only with great difficulty in the case of components of complex shape. The partial elimination of these difficulties is associated with considerable effort.

Aufgabe der Erfindung ist es, Bauteile bzw. Schichtverbundkörper mit einer geschützten Oberfläche zu versehen, auf bereits einer Formgebung unterworfenen Teilen, insbesondere kompliziert geformten Teilen, und diese dabei in gleichmäßiger Schichtdicke, ohne großen Aufwand überziehen zu können.The object of the invention is to provide components or layered composite bodies with a protected surface, on parts already subjected to a shaping, in particular parts of complex shape, and to be able to cover them in a uniform layer thickness without great effort.

Die Lösung besteht in einem Verfahren, bei dem folgende Schritte durchgeführt werden:

  • a) ein Pulver eines Ausgangsmaterials für die Schicht wird mit Lösungsmittel in eine Suspension gebracht,
  • b) die Suspension wird auf einer Temperatur, knapp oberhalb des Gefrierpunktes des Lösungsmittels bereitgehalten,
  • c) das zu beschichtende Bauteil wird auf eine Temperatur unterhalb des Gefrierpunkts des Lösungsmittels bereitgehalten,
  • d) das Bauteil wird in diese Suspension eingetaucht, und es friert eine Schicht des in der Suspension vorhandenen Ausgangspulvers fest, deren Dicke von der Temperatur des Bauteils und der Zeitdauer des Eintauchens des Bauteils in das Bad der Suspension abhängt,
  • e) das mit der Schicht überzogene Bauteil wird einer Gefriertrocknung ausgesetzt und bis zum Abschluß des Gefriertrocknens nicht auf eine Temperatur oberhalb des Gefrierpunktes des Lösungsmittels erwärmt.
The solution is a process that does the following:
  • a) a powder of a starting material for the layer is brought into a suspension with solvent,
  • b) the suspension is kept at a temperature just above the freezing point of the solvent,
  • c) the component to be coated is kept at a temperature below the freezing point of the solvent,
  • d) the component is immersed in this suspension and a layer of the starting powder present in the suspension freezes, the thickness of which depends on the temperature of the component and the duration of the immersion of the component in the bath of the suspension,
  • e) the component coated with the layer is subjected to freeze-drying and is not heated to a temperature above the freezing point of the solvent until freeze-drying is complete.

In vorteilhafter Weise kann mit der Erfindung praktisch jede gewünschte Schichtdicke gleichmäßig erzeugt werden, und dabei können einzelne Schritte des Verfahrens beliebig oft wiederholt werden, wie z.B. die Herstellung des Tauchüberzuges.Advantageously, practically any desired layer thickness can be produced uniformly with the invention, and individual steps of the method can be repeated as often as desired, e.g. the production of the diving cover.

Je nach gewünschtem Zweck der Schicht können anschließend an die Herstellung des Überzuges eine Wärmebehandlung und andere Behandlungen des überzogenen Bauteils durchgeführt werden, wie z.B. ein Dichtsintern oder Dichtpressen an der Oberfläche. Bei besonderen Anforderungen können auch ein Sinter- oder ein Preßprogramm kombiniert werden (heißisostatisch Pressen). Auch Energiestrahlbehandlungen der Oberfläche, Dotieren, Infiltration von anderen Stoffen als Schichtwerkstoff und in anderer Form als Pulver können im Rahmen vorliegender Erfindung angewandt werden. Mit Vorteil kann in der Suspensionsflüssigkeit ein Bindemittel gelöst werden, das eine erhöhte Grünfestigkeit der Pulverschicht bewirkt, wenn als Schichtwerkstoff ein Pulver verwendet wird, dessen mittlere Korngröße oberhalb 25 µm liegt. Das organische Bindemittel wird dabei zu Beginn des Sintervorganges oder in einer separaten Wärmebehandlung wieder entfernt.Depending on the desired purpose of the layer, a heat treatment and other treatments of the coated component can be carried out after the production of the coating, such as e.g. sealing sintering or sealing on the surface. A sintering or pressing program can also be combined for special requirements (hot isostatic pressing). Energy beam treatments of the surface, doping, infiltration of substances other than layer material and in a form other than powder can also be used within the scope of the present invention. A binder can advantageously be dissolved in the suspension liquid, which brings about an increased green strength of the powder layer if a powder is used as the layer material, the average grain size of which is above 25 μm. The organic binder is removed again at the beginning of the sintering process or in a separate heat treatment.

Weitere vorteilhafte Merkmale der Erfindung sind den übrigen Patentansprüchen sowie der Beschreibung von Ausführungsbeispielen zu entnehmen.Further advantageous features of the invention can be found in the remaining claims and the description of exemplary embodiments.

Bevorzugt wird die Erfindung für Schutzschichten angewandt, und hier besonders für solche, die kombinierten Anforderungen unterworfen sind. Hauptanwendungsgebiet sind der allgemeine Maschinenbau, Bauteile für Fahrzeuge jeglicher Art, aber auch stationäre Anlagen wie Fabrikationsanlagen, insbesondere des Apparatebaus. Die Grundkörper des als Endprodukt der Erfindung zu zählenden Verbundkörpers können aus nahezu beliebigen Materialien ausgewählt werden, wie metallischen Werkstoffen, Metallverbindungen, intermetallischen Phasen, Keramik, Metallkeramik, Metallglas, Glaskeramik und/oder Kombinationen der o.g. Stoffe mit Kunststoffen. Als Schutzschichten können je nach Beanspruchungsart hierfür an sich bekannte Stoffe bzw. Werkstoffkombinationen ausgewählt werden. Die in den Beispielen angegebenen Prozentzahlen der Bestandteile für die Ausgangswerkstoffe bzw. Gemische bzw. Suspensionen können in weiten Grenzen verändert werden.The invention is preferably used for protective layers, and here in particular for those which are subject to combined requirements. The main area of application is general mechanical engineering, components for vehicles of all kinds, but also stationary systems such as manufacturing systems, especially apparatus engineering. The base body of the composite body to be counted as the end product of the invention can be selected from almost any materials, such as metallic materials, metal compounds, intermetallic phases, ceramics, metal ceramics, metal glass, glass ceramics and / or combinations of the above. Fabrics with plastics. Depending on the type of stress, substances or combinations of materials known per se can be selected as protective layers. The percentages of the constituents for the starting materials or mixtures or suspensions given in the examples can be changed within wide limits.

Die Vorrichtungen, die zur Durchführung des erfindungsgemäßen Verfahrens nötig sind, sind von einfacher und üblicher Art, insbesondere was die für das Tauchverfahren nötigen Behältnisse anbelangt oder die Kühlmittel für das Bauteil wie Kühlschränke. Für das Gefriertrocknen können die in der Lebensmitteltechnologie üblicherweise verwendeten Gefriertrockner angewandt werden und ebenso sind die Glüh- und Sinteröfen bzw. Pressen oder sonstigen Nachbehandlungseinrichtungen an sich bekannter Art.The devices which are necessary for carrying out the method according to the invention are of a simple and customary type, in particular as regards the containers required for the immersion method or the coolants for the component, such as refrigerators. The freeze dryers commonly used in food technology can be used for freeze drying, and the annealing and sintering ovens or presses or other post-treatment devices are also known per se.

AusführungsbeispieleEmbodiments

  • 1. Wärmedämmschicht für Turbinenleitschaufeln
    • - Suspension:
      • 50 Vol% H20
      • 50 Vol% Zr 02-Pulver mit 5% Y2 Os teilstabilisiert, mittlere Korngröße des Pulvers: 0,5 J.lm
      • Temperatur der Suspension: + 5 Grad Celsius
    • - Bauteil: Turbinenlaufschaufel
      • Temperatur -20 Grad Celsius
    • - Eintauchen des Teiles: 10 s
    • - Gefriertrocknen (-10 Grad Celsius, Vakuum 1 Pa (10-2mbar), 2 h)
    • -Sintern: 1200 Grad Celsius, 1 h im Vakuum
    1. Thermal insulation layer for turbine guide vanes
    • - suspension:
      • 50 vol% H 2 0
      • 50 vol% Zr 0 2 powder partially stabilized with 5% Y 2 O s , average grain size of the powder: 0.5 J.lm
      • Temperature of the suspension: + 5 degrees Celsius
    • - Component: turbine blade
      • Temperature -20 degrees Celsius
    • - Immersion of the part: 10 s
    • - Freeze drying (-10 degrees Celsius, vacuum 1 Pa (10-2mbar), 2 h)
    • -Sinter: 1200 degrees Celsius, 1 h in vacuum
  • 2. Korrosionsschutzschicht für Turbinenleitschaufeln:
    • - Suspension:
      • 54,5 Vol% H2 O
      • 45 Vol% Co Cr AI Y - Pulver, mittlere Korngröße 30 wm
      • 0,5 Vol% Polyvinylalkohol, Rest: Wasser
    • - Bauteil: Turbinenleitschaufeln,
      • Temperatur-10 Grad Celsius
    • - Eintauchen des Bauteils: 5 s
    • - Bauteil erneut auf - 10 Grad Celsius kühlen
    • - Eintauchen: -5 s
    • - Gefriertrocknen (-10 Grad Celsius, Vakuum 1 Pa (1 0-2mbar), 4 h)
    • - Ausbrennen des Polyvinylalkohols:
      • Warmbehandlung, kontinuierliches Aufheizen von Raumtemperatur auf 600 Grad Celsius in 24 h im Vakuum, Druck (p) < 1 Pa (10-2mbar)
    • - Sintern der Schicht:
      • 1150 Grad Celsius, 1/2 h, Vakuum, Druck (p) < 1 Pa (10-2mbar)
    2. Corrosion protection layer for turbine guide vanes:
    • - suspension:
      • 54.5 vol% H 2 O
      • 45 vol% Co Cr AI Y powder, average grain size 30 wm
      • 0.5 vol% polyvinyl alcohol, rest: water
    • - component: turbine guide vanes,
      • Temperature -10 degrees Celsius
    • - Immersion of the component: 5 s
    • - Cool the component again to - 10 degrees Celsius
    • - Immersion: -5 s
    • - Freeze drying (-10 degrees Celsius, vacuum 1 Pa (1 0-2mbar), 4 h)
    • - Burning out the polyvinyl alcohol:
      • Heat treatment, continuous heating from room temperature to 600 degrees Celsius in 24 h in vacuum, pressure (p) <1 Pa (10-2mbar)
    • - Sintering the layer:
      • 1150 degrees Celsius, 1/2 h, vacuum, pressure (p) <1 Pa (10- 2 mbar)

Claims (10)

1. A method of producing protective coatings against thermal and/or chemical and/or mechanical stresses on components, particularly components of complicated shape such as turbine blades, and in which the following steps are carried out:
a) a powder of a starting material for the coating is brought into suspension with a solvent,
b) the suspension is held ready at a temperature just above the freezing point of the solvent,
c) the component to be coated is held ready at a temperature below the freezing point of the solvent
d) the component is dipped into the suspension and a coating of the starting powder present in the suspension freezes solid, its thickness depending on the temperature of the component and the duration of immersion of the component in the bath of suspension,
e) coated with the coating material, the component is exposed to a freeze drying process and until the freeze drying process is concluded, it is not heated to a temperature above the freezing point of the solvent.
2. A method according to claim 1, characterised in that as the starting powder a metallic or a ceramic powder of a granulation less than 50 microns and an evaporable solvent is used.
3. A method according to claim 1 or 2, characterised in that an organic expellable binder is added to the suspension if the granulation is above 25 microns.
4. A method according to claim 1, characterised in that the starting powder is suspended in a liquid such as water, this suspension being kept in a vessel at a bath temperature between 0 and 20°.
5. A method according to one of the preceding claims, characterised in that the component is brought to a temperature of up to about -20°C and then dipped in the bath of the suspension for a few seconds.
6. A method according to one of the preceding claims, characterised in that, coated with the dipped coating, the component is freeze dried in a vacuum of the magnitude of 1 Pa (10-2 mbar) or better, at temperatures of between -10° and -30°C for several hours.
7. A method according to one of the preceding claims, characterised in that the freeze drying process is followed by a heat treatment consisting of the gradual and continuous heating to a temperature of about 600°C and subsequently, in a second stage of the heat treatment, sintering is carried out at a temperature above 1000°C.
8. A method according to one of the preceding claims, characterised in that the working operations of dipping the cooled component into the bath of suspension and the freeze drying are repeated for a desired coating thickness.
9. A method according to one of the preceding claims, racterised in that when a binder is used, this is removed again at the onset of the sintering process or in a separate heat treatment.
10. A method according to one of the preceding claims, characterised in that propanol is used as an aid when the freeze drying process takes place.
EP87110805A 1986-08-21 1987-07-25 Method of producing protective coatings Expired - Lifetime EP0257319B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19863628363 DE3628363A1 (en) 1986-08-21 1986-08-21 PROCESS FOR PRODUCING PROTECTIVE LAYERS
DE3628363 1986-08-21

Publications (2)

Publication Number Publication Date
EP0257319A1 EP0257319A1 (en) 1988-03-02
EP0257319B1 true EP0257319B1 (en) 1990-06-27

Family

ID=6307854

Family Applications (1)

Application Number Title Priority Date Filing Date
EP87110805A Expired - Lifetime EP0257319B1 (en) 1986-08-21 1987-07-25 Method of producing protective coatings

Country Status (4)

Country Link
US (1) US4902536A (en)
EP (1) EP0257319B1 (en)
JP (1) JPS6353278A (en)
DE (2) DE3628363A1 (en)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3821819A1 (en) * 1988-06-29 1990-02-08 Nokia Unterhaltungselektronik Process for producing a thin layer
ES2009355A6 (en) * 1988-10-17 1989-09-16 Sintermetal Sa Method to obtain coatings on mechanical parts by P/M techniques.
JPH0765232B2 (en) * 1989-10-12 1995-07-12 三菱レイヨン株式会社 Amorphous alloy manufacturing method

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1126103A (en) * 1954-06-17 1956-11-15 Birmingham Small Arms Co Ltd Heat resistant steel or alloy object
DE1496660B1 (en) * 1964-03-06 1970-02-12 Sigri Elektrographit Gmbh Highly heat-resistant molded body with a scale-resistant coating and process for its production
CH493648A (en) * 1965-11-26 1970-07-15 Moser Rudolf Method and device for producing a permanent coating on metallic workpieces
US3475161A (en) * 1967-03-14 1969-10-28 Howmet Corp Method of forming cemented carbide coatings on metal surfaces by employing volatile,organic liquid solvents and organic binders
GB1271281A (en) * 1968-07-31 1972-04-19 Ethyl Corp Coating of webs by freeze-drying and products therefrom
US3852105A (en) * 1972-04-07 1974-12-03 Rca Corp Fabrication of dark heaters
DE2718758A1 (en) * 1977-04-27 1978-11-02 Siemens Ag Barium titanate ceramic tubes metallisation - by dipping into silver suspension ultrasonically vibrating and extracting from suspension at specified rates
US4328285A (en) * 1980-07-21 1982-05-04 General Electric Company Method of coating a superalloy substrate, coating compositions, and composites obtained therefrom

Also Published As

Publication number Publication date
EP0257319A1 (en) 1988-03-02
US4902536A (en) 1990-02-20
DE3763430D1 (en) 1990-08-02
JPS6353278A (en) 1988-03-07
DE3628363A1 (en) 1988-02-25

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