EP3880870A1 - Method for pickling a turbomachine component - Google Patents

Method for pickling a turbomachine component

Info

Publication number
EP3880870A1
EP3880870A1 EP19829275.7A EP19829275A EP3880870A1 EP 3880870 A1 EP3880870 A1 EP 3880870A1 EP 19829275 A EP19829275 A EP 19829275A EP 3880870 A1 EP3880870 A1 EP 3880870A1
Authority
EP
European Patent Office
Prior art keywords
enclosure
gas mixture
pickling
gas
flow
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.)
Pending
Application number
EP19829275.7A
Other languages
German (de)
French (fr)
Inventor
Noureddine Bourhila
Laurent BESNAULT
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.)
Safran Aircraft Engines SAS
Original Assignee
Safran Aircraft Engines SAS
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 Safran Aircraft Engines SAS filed Critical Safran Aircraft Engines SAS
Publication of EP3880870A1 publication Critical patent/EP3880870A1/en
Pending legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D5/00—Blades; Blade-carrying members; Heating, heat-insulating, cooling or antivibration means on the blades or the members
    • F01D5/005—Repairing methods or devices
    • 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
    • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F1/00—Etching metallic material by chemical means
    • C23F1/10—Etching compositions
    • C23F1/12—Gaseous compositions
    • 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
    • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
    • C23G5/00—Cleaning or de-greasing metallic material by other methods; Apparatus for cleaning or de-greasing metallic material with organic solvents
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D25/00—Component parts, details, or accessories, not provided for in, or of interest apart from, other groups
    • F01D25/002—Cleaning of turbomachines
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
    • F05D2230/00—Manufacture
    • F05D2230/80—Repairing, retrofitting or upgrading methods

Definitions

  • the invention relates to the general field of surface treatment methods, and more particularly the methods of stripping surfaces of parts of turbomachinery.
  • a turbomachine conventionally comprises at least one flow stream through which circulates an air flow which is compressed by one or more compressors before entering a combustion chamber where the air is mixed with a fuel and then ignited .
  • the mixture of burnt gases then rotates one or more turbines which rotate the compressor (s), the gas flow then being ejected.
  • Turbine parts exposed to very high temperatures, are generally treated or coated with refractory materials or alloys so as to limit their degradation.
  • aluminides for example titanium aluminides
  • oxides for example oxides molybdenum, or ceramics
  • thermochemical operation is carried out on the part, conventionally in an oven at high temperature and under a fluorinated atmosphere (conventionally called FIC, from English Fluorite Ion Cleaning).
  • Sandblasting operations which are mechanical abrasion operations, naturally attack the substrate.
  • the succession of these operations also generates a difficulty in the quality of the treatment. Indeed if a step is not carried out perfectly and leaves areas not pickled, the following processing operations will also be degraded and the part can then be rendered unusable, because the reiteration of the process so as to eliminate the areas of remaining coating would attack the substrate too deep.
  • the chemical baths used contain substances or components that are dangerous for operators, such as hydrofluoric acids conventionally used in pickling baths for aluminides.
  • An object of the invention is to simplify the process of pickling the surfaces of parts of turbomachinery.
  • Another object of the invention is to reduce the risk of degradation of the substrate during the process of pickling parts of turbomachinery.
  • Another object of the invention is to limit the use of dangerous products for operators.
  • the invention proposes a process for pickling a part of a turbomachine, comprising the following steps:
  • the gaseous mixture also comprises dihydrogen
  • the heating stage is carried out at a temperature above 1000 ° C. and the gas mixture injection stage is carried out by causing a flow of gas mixture having a flow rate of between 6 and 15 times to flow through the enclosure the volume of the enclosure per hour.
  • Such a method makes it possible in particular to eliminate in a thermochemical treatment phase the layers of the coating based on aluminides and the layers of the coating based on metal oxides, which makes it possible to strip the part and to reveal the substrate without requiring a chemical bath or sandblasting step to remove this type of layer.
  • the pickling process is therefore simplified and made safer, the substrate not being degraded during the process and the operators not being brought into contact with dangerous products.
  • the gas mixture comprises fluorine; halogenated element allowing a higher reaction rate than when using other halogenated elements;
  • the temperature of the heating stage is greater than 1030 ° C; this makes it possible to increase the efficiency of the pickling and cleaning process, in particular by increasing the reaction kinetics;
  • the gas mixture further comprises an inert gas, for example argon; this makes it possible to transport the reactive gases and to contribute to the homogenization of the gas mixture in the oven enclosure;
  • an inert gas for example argon
  • a concentration of the halogenated gas in the gas mixture is between 4% and 12% in mass percentages, preferably between 6% and 8% in mass percentages; this makes it possible to control the amount of reactive gas introduced into the enclosure and thus control the reaction on the surface of the parts, in particular by controlling the rate of diffusion of the species;
  • the flow rate of the gas mixture flow is between 8 and 12 times the volume of the enclosure per hour; this provides the amount of active gas required and sufficient to operate an effective reaction on the entire room in the enclosure;
  • a total pressure in the enclosure is substantially equal to atmospheric pressure
  • a total pressure in the enclosure is lower than atmospheric pressure; this saves time, requires less gas and is more efficient because gases can penetrate cracks, cracks and cavities more quickly and very effectively;
  • FIG. 1 is a schematic representation representing the production of a process for pickling a part according to the invention.
  • the invention relates to a process for pickling a part 1 of a turbomachine, characterized in that it comprises the following steps:
  • the gas mixture 3 comprising at least one halogenated gas
  • the gaseous mixture also comprises dihydrogen
  • the heating step is carried out at a temperature above 1000 ° C.
  • the gas mixture injection step 3 is carried out by circulating through the enclosure 2 a flow of gaseous mixture having a flow rate of between 6 and 15 times the volume of the enclosure 2 per hour.
  • the invention advantageously applies to a part 1 comprising a coating 4 comprising at least one aluminide layer 41 comprising one or more species of aluminides, or at least one oxide layer 42 comprising one or more species of metal oxides, or a combination of such layers.
  • the halogenated gas or gases react with the aluminide layers 41 and the oxide layers 42 according to the following reactions:
  • H of hydrogen H of hydrogen, M a metal, O of oxygen, Al of aluminum, Sc a transition metal.
  • X can be fluorine, chlorine, bromine or iodine and Sc can be Nickel, cobalt, titanium or any other transition metal.
  • the halogen species X comprises fluorine, for example in the form of hydrofluoric acid.
  • Fluorine has a high reactivity and allows a faster reaction than with the use of other halogenated elements.
  • thermochemical treatment phase The layers of the coating based on aluminides 41 and the layers of the coating based on metallic oxides 42 are therefore eliminated in a thermochemical treatment phase, which makes it possible to strip the part 1 and to reveal the substrate 5 without requiring a chemical bath or sandblasting step to remove this type of layer.
  • the pickling process is therefore simplified and made safer, the substrate 5 not being degraded during the process and the operators not being brought into contact with dangerous products.
  • the enclosure 2 is continuously traversed by a flow of gaseous mixture 3 which has a flow rate representing between 6 and 15 times the volume of the enclosure 2 per hour, preferably between 8 and 12 times the volume of the enclosure 2 per hour . This makes it possible to supply the quantity of active gas necessary and sufficient to operate an effective reaction on the entire part in the enclosure (in terms of volume or surface).
  • the gas mixture flow 3 can be adapted as a function of the quantity of parts 1 to be treated, or the total surface to be stripped.
  • the flow rate of halogenated gas can be between 6L / min and 10L / min, and the flow rate of dihydrogen can be between 130 L / min and 160 L / min for an enclosure having a volume of order of 1 m3 in which 45 pieces are placed 1.
  • the heating phase includes a rise in temperature, a temperature holding level and a cooling.
  • the temperature holding stage can last between 2 hours and 10 hours, preferably between 3.5 hours and 5.5 hours (include 3 hours and 30 minutes or 5 hours and 30 minutes).
  • the temperature of the holding bearing is greater than 1000 ° C, preferably greater than 1030 ° C, for example between 1035 ° C and 1055 ° C.
  • Such temperature intervals have the effect of increasing the efficiency of the pickling and cleaning process compared to a simple cleaning of oxides, as is the case with standard FIC processes.
  • the kinetics of the reactions involved is a function of the temperature.
  • a sandblasting step can be carried out prior to the thermochemical treatment. This eliminates combustion residues, for example of scale, formed on the surface of the coating 4 during the operation of the turbomachine, as well as any thermal barrier layers 43 made of ceramic and the passivating layers 44 which cover them, for example layers comprising calcium-magnesium-aluminosilicate.
  • the sandblasting step thus makes it possible to reveal the aluminide layers 41 and the oxide layers 42 of the coating, which will be eliminated in a thermochemical cycle phase.
  • the sanding step carried out upstream does not therefore represent a danger for the substrate 5.
  • one or more parts 1 are placed in a closed enclosure 2, preferably on a grid, allowing better circulation of the gas mixture 3 along the entire surface of the part or parts 1, which improves the treatment.
  • the gas mixture 3 is then injected into the enclosure 2.
  • the gas mixture 3 also comprises one component or a combination of components from the following components:
  • the gas mixture 3 can also advantageously comprise dihydrogen.
  • the gas mixture 3 also comprises an inert gas, for example helium, neon, Argon, krypton, xenon or radon, or a combination of these elements.
  • an inert gas for example helium, neon, Argon, krypton, xenon or radon, or a combination of these elements.
  • the concentration of halogenated gas in the gas mixture 3 is advantageously between 4% and 12%, preferably between 6% and 8%, for example in mass percentages.
  • the concentration of halogenated gases has in particular an influence on the rate of diffusion of the reactive species, with the temperature.
  • the supply of enclosure 2 with gas mixture 3 follows a sequential cycle, and presents:
  • thermochemical treatment is not completed.
  • thermochemical treatment can be carried out at atmospheric pressure, or preferably under reduced pressure (or low pressure, that is to say less than 300 mbar). Treatment under reduced pressure saves time, requires less gas and is more efficient because gases can penetrate cracks, cracks and cavities more quickly and very effectively, even if they are too narrow and deep.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • General Engineering & Computer Science (AREA)
  • Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
  • Turbine Rotor Nozzle Sealing (AREA)

Abstract

The invention relates to a method for pickling a turbomachine component (1), comprising the following steps: positioning the component in a closed chamber (2), injecting a gas mixture (3) into the chamber (2), the gas mixture (3) comprising a halogenated gas, heating the chamber (2), the method being characterised in that: the gas mixture further comprises dihydrogen, the heating step is carried out at a temperature higher than 1000°C and the step of injecting the gas mixture (3) is carried out by circulating through the chamber (2) a flow of gas mixture (3) having a flow rate between 6 and 15 times the volume of the chamber (2) per hour.

Description

PROCEDE DE DECAPAGE D’UNE PIECE DE TURBOMACHINE  PROCESS FOR STRIPPING A TURBOMACHINE PART
DOMAINE TECHNIQUE GÉNÉRAL ET ART ANTÉRIEUR GENERAL TECHNICAL AREA AND PRIOR ART
L’invention concerne le domaine général des procédés de traitements de surfaces, et plus particulièrement les procédés de décapage de surfaces de pièces de turbomachines.  The invention relates to the general field of surface treatment methods, and more particularly the methods of stripping surfaces of parts of turbomachinery.
Une turbomachine comporte classiquement au moins une veine d’écoulement à travers laquelle circule un flux d’air qui est compressé par un ou plusieurs compresseurs avant d’entrer dans une chambre de combustion où l’air est mélangé avec un carburant puis mis à feu.  A turbomachine conventionally comprises at least one flow stream through which circulates an air flow which is compressed by one or more compressors before entering a combustion chamber where the air is mixed with a fuel and then ignited .
Le mélange de gaz brûlés entraîne ensuite en rotation une ou plusieurs turbines qui entraînent en rotation le ou les compresseurs, le flux de gaz étant ensuite éjecté.  The mixture of burnt gases then rotates one or more turbines which rotate the compressor (s), the gas flow then being ejected.
Les pièces de turbines, exposées à de très hautes températures, sont généralement traitées ou revêtues au moyen de matériaux ou d’alliages réfractaires de manière à limiter leur dégradation.  Turbine parts, exposed to very high temperatures, are generally treated or coated with refractory materials or alloys so as to limit their degradation.
Il est par exemple connu de revêtir de telles pièces d’une ou plusieurs couches d’alliages d’aluminium, dits aluminures, par exemple des aluminures de titane, et/ou d’une ou plusieurs couches d’oxydes, par exemple des oxydes de molybdène, ou des céramiques, formant une barrière thermique en surface de la pièce.  It is for example known to coat such parts with one or more layers of aluminum alloys, called aluminides, for example titanium aluminides, and / or with one or more layers of oxides, for example oxides molybdenum, or ceramics, forming a thermal barrier on the surface of the part.
Lorsqu’il est nécessaire de réparer de telles pièces, des opérations de décapages des revêtements sont nécessaires afin de réhabiliter le matériau de base composant la pièce, appelé substrat.  When it is necessary to repair such parts, stripping operations on the coatings are necessary in order to rehabilitate the basic material making up the part, called the substrate.
Ces étapes de décapage comportent classiquement plusieurs étapes :  These stripping steps conventionally include several steps:
- au moins une étape de sablage ou de bain chimique de manière à éliminer la barrière thermique,  - at least one step of sandblasting or chemical bath so as to eliminate the thermal barrier,
- au moins une étape de bain chimique de manière à éliminer les revêtements en aluminures,  - at least one chemical bath step so as to remove the aluminide coatings,
- au moins une étape supplémentaire de sablage de la pièce à la sortie du bain chimique de manière à éliminer les résidus restants.  - at least one additional step of sandblasting the part at the outlet of the chemical bath so as to remove the remaining residues.
Ces opérations n’éliminent toutefois pas les oxydes ou contaminants incorporés dans les criques ou les défauts sur les surfaces des pièces. Afin de nettoyer ces criques d’éventuels oxydes ou de corrosion, une étape supplémentaire au cours de laquelle une opération thermochimique est effectuée sur la pièce, classiquement dans un four à haute température et sous atmosphère fluorée (appelée classiquement FIC, de l’anglais Fluorine Ion Cleaning). However, these operations do not eliminate the oxides or contaminants incorporated in the cracks or the defects on the surfaces of the parts. In order to clean these cracks from possible oxides or corrosion, an additional step during which a thermochemical operation is carried out on the part, conventionally in an oven at high temperature and under a fluorinated atmosphere (conventionally called FIC, from English Fluorite Ion Cleaning).
De telles opérations sont cependant source de risques pour les pièces en raison du danger potentiel d’attaque chimique du matériau du substrat par les produits chimiques utilisés.  However, such operations are a source of risk for parts due to the potential danger of chemical attack on the substrate material by the chemicals used.
Les opérations de sablage, qui sont des opérations d’abrasion mécanique, agressent naturellement le substrat.  Sandblasting operations, which are mechanical abrasion operations, naturally attack the substrate.
De plus, la recherche de gain de poids afin de minimiser le poids total des turbomachines amène les pièces de turbomachine à présenter des parois de plus en plus fines, ce qui limite la marge de consommation de substrat au cours de tels procédés de décapage.  In addition, the search for weight gain in order to minimize the total weight of the turbomachines causes the parts of the turbomachine to present increasingly thinner walls, which limits the margin of substrate consumption during such pickling processes.
La succession de ces opérations génère également une difficulté dans la qualité du traitement. En effet si une étape n’est pas réalisée parfaitement et laisse des zones non décapées, les opérations de traitement suivantes s’en trouveront également dégradées et la pièce peut alors être rendue inutilisable, car la réitération du procédé de manière à éliminer les zones de revêtement restantes attaquerait le substrat trop en profondeur.  The succession of these operations also generates a difficulty in the quality of the treatment. Indeed if a step is not carried out perfectly and leaves areas not pickled, the following processing operations will also be degraded and the part can then be rendered unusable, because the reiteration of the process so as to eliminate the areas of remaining coating would attack the substrate too deep.
D’autre part, les bains chimiques utilisés contiennent des substances ou composants dangereux pour les opérateurs, tels des acides fluorhydriques utilisés classiquement dans les bains de décapage d’aluminures.  On the other hand, the chemical baths used contain substances or components that are dangerous for operators, such as hydrofluoric acids conventionally used in pickling baths for aluminides.
PRÉSENTATION GÉNÉRALE DE L’INVENTION  OVERVIEW OF THE INVENTION
Un but de l’invention est de simplifier le procédé de décapage des surfaces des pièces de turbomachines.  An object of the invention is to simplify the process of pickling the surfaces of parts of turbomachinery.
Un autre but de l’invention est de réduire le risque de dégradation du substrat au cours de procédé de décapage de pièces de turbomachines.  Another object of the invention is to reduce the risk of degradation of the substrate during the process of pickling parts of turbomachinery.
Un autre but de l’invention est de limiter l’utilisation de produits dangereux pour les opérateurs.  Another object of the invention is to limit the use of dangerous products for operators.
A cet effet, l’invention propose un procédé de décapage d’une pièce de turbomachine, comprenant les étapes suivantes :  To this end, the invention proposes a process for pickling a part of a turbomachine, comprising the following steps:
- Positionnement de la pièce dans une enceinte fermée, - Injection d’un mélange gazeux dans l’enceinte, le mélange gazeux comprenant un gaz halogéné, - Positioning of the part in a closed enclosure, - Injection of a gas mixture into the enclosure, the gas mixture comprising a halogenated gas,
- Chauffage de l’enceinte,  - Heating of the enclosure,
le procédé étant caractérisé en ce que : the method being characterized in that:
- le mélange gazeux comprend en outre du dihydrogène, the gaseous mixture also comprises dihydrogen,
- l’étape de chauffage est réalisée à une température supérieure à 1000° C et l’étape d’injection de mélange gazeux est réalisée en faisant circuler à travers l’enceinte un flux de mélange gazeux présentant un débit compris entre 6 et 15 fois le volume de l’enceinte par heure.  the heating stage is carried out at a temperature above 1000 ° C. and the gas mixture injection stage is carried out by causing a flow of gas mixture having a flow rate of between 6 and 15 times to flow through the enclosure the volume of the enclosure per hour.
Un tel procédé permet notamment d’éliminer en une phase de traitement thermochimique les couches du revêtement à base d’aluminures et les couches du revêtement à base d’oxydes métallique, ce qui permet de décaper la pièce et de révéler le substrat sans requérir à une étape de bain chimique ni de sablage pour éliminer ce type de couches.  Such a method makes it possible in particular to eliminate in a thermochemical treatment phase the layers of the coating based on aluminides and the layers of the coating based on metal oxides, which makes it possible to strip the part and to reveal the substrate without requiring a chemical bath or sandblasting step to remove this type of layer.
Le procédé de décapage est donc simplifié et rendu plus sûr, le substrat n’étant pas dégradé lors du procédé et les opérateurs n’étant pas mis en contact avec des produits dangereux.  The pickling process is therefore simplified and made safer, the substrate not being degraded during the process and the operators not being brought into contact with dangerous products.
Un tel procédé est avantageusement complété par les caractéristiques suivantes, prises seules ou en combinaison :  Advantageously, such a process is completed by the following characteristics, taken alone or in combination:
- le mélange gazeux comporte du fluor ; élément halogéné permettant une vitesse de réaction plus élevée que lors de l’utilisation d’autre éléments halogénés ; - The gas mixture comprises fluorine; halogenated element allowing a higher reaction rate than when using other halogenated elements;
- la température de l’étape de chauffage est supérieure à 1030°C ; cela permet d’augmenter l’efficacité du procédé de décapage et nettoyage, notamment en augmentant la cinétique de réaction ;  - the temperature of the heating stage is greater than 1030 ° C; this makes it possible to increase the efficiency of the pickling and cleaning process, in particular by increasing the reaction kinetics;
- le mélange gazeux comporte en outre un gaz inerte, par exemple de l’argon ; cela permet de transporter les gaz réactifs et de contribuer à l’homogénéisation du mélange gazeux dans l’enceinte du four ; - The gas mixture further comprises an inert gas, for example argon; this makes it possible to transport the reactive gases and to contribute to the homogenization of the gas mixture in the oven enclosure;
- une concentration du gaz halogéné dans le mélange gazeux est comprise entre 4% et 12% en pourcentages massiques, préférentiellement entre 6% et 8% en pourcentages massiques ; cela permet de contrôler la quantité du gaz réactif introduit dans l’enceinte ainsi contrôler la réaction en surface des pièces, notamment en maîtrisant la vitesse de diffusion des espèces ;  a concentration of the halogenated gas in the gas mixture is between 4% and 12% in mass percentages, preferably between 6% and 8% in mass percentages; this makes it possible to control the amount of reactive gas introduced into the enclosure and thus control the reaction on the surface of the parts, in particular by controlling the rate of diffusion of the species;
- le débit du flux de mélange gazeux est compris à entre 8 et 12 fois le volume de l’enceinte par heure ; cela permet d’apporter la quantité de gaz actif nécessaire et suffisante pour opérer une réaction efficace sur la totalité de pièce dans l’enceinte ; - The flow rate of the gas mixture flow is between 8 and 12 times the volume of the enclosure per hour; this provides the amount of active gas required and sufficient to operate an effective reaction on the entire room in the enclosure;
- une pression totale dans l’enceinte est sensiblement égale à la pression atmosphérique ;  - a total pressure in the enclosure is substantially equal to atmospheric pressure;
- une pression totale dans l’enceinte est inférieure à la pression atmosphérique ; cela permet un gain de temps, demande moins de gaz et est plus efficace car les gaz peuvent pénétrer plus rapidement et de façon très efficace dans des criques, fissures et cavités ;  - a total pressure in the enclosure is lower than atmospheric pressure; this saves time, requires less gas and is more efficient because gases can penetrate cracks, cracks and cavities more quickly and very effectively;
-le procédé consiste en une succession des étapes de :  -the process consists of a succession of steps of:
- Sablage de la pièce (1 ),  - Sandblasting of the part (1),
- Positionnement de la pièce (1 ) sablée dans l’enceinte (2) fermée,  - Positioning of the sanded part (1) in the closed enclosure (2),
- Injection du mélange gazeux (3) dans l’enceinte (2) et  - Injection of the gas mixture (3) into the enclosure (2) and
- Chauffage de l’enceinte (2).  - Heating of the enclosure (2).
PRÉSENTATION DES FIGURES  PRESENTATION OF THE FIGURES
La figure 1 est une représentation schématique représentant la réalisation d’un procédé de décapage d’une pièce selon l’invention.  FIG. 1 is a schematic representation representing the production of a process for pickling a part according to the invention.
D’autres caractéristiques et avantages de l’invention ressortiront encore de la description qui suit, laquelle est purement illustrative et non limitative, et doit être lue en regard de la figure unique annexée qui est un schéma représentant un dispositif permettant de mettre en oeuvre un procédé de décapage d’une pièce selon l’invention.  Other characteristics and advantages of the invention will emerge from the description which follows, which is purely illustrative and not limiting, and should be read with reference to the single appended figure which is a diagram representing a device making it possible to implement a pickling process of a part according to the invention.
DESCRIPTION D’UN OU PLUSIEURS MODES DE MISE EN ŒUVRE ET DE RÉALISATION  DESCRIPTION OF ONE OR MORE MODES OF IMPLEMENTATION AND IMPLEMENTATION
L’invention concerne à un procédé de décapage d’une pièce 1 de turbomachine, caractérisé en ce qu’il comprend les étapes suivantes :  The invention relates to a process for pickling a part 1 of a turbomachine, characterized in that it comprises the following steps:
- Positionnement de la pièce 1 dans une enceinte 2 fermée,  - Positioning of part 1 in a closed enclosure 2,
- Injection d’un mélange gazeux 3 dans l’enceinte 2, le mélange gazeux 3 comportant au moins un gaz halogéné,  - Injection of a gas mixture 3 into the enclosure 2, the gas mixture 3 comprising at least one halogenated gas,
- Chauffage de l’enceinte 2,  - Heating of enclosure 2,
Le procédé étant caractérisé en ce que :  The method being characterized in that:
- le mélange gazeux comprend en outre du dihydrogène,  the gaseous mixture also comprises dihydrogen,
- l’étape de chauffage est réalisée à une température supérieure à 1000° C, et the heating step is carried out at a temperature above 1000 ° C., and
- l’étape d’injection de mélange gazeux 3 est réalisée en faisant circuler à travers l’enceinte 2 un flux de mélange gazeux présentant un débit compris entre 6 et 15 fois le volume de l’enceinte 2 par heure. L’invention s’applique avantageusement à une pièce 1 comportant un revêtement 4 comportant au moins une couche aluminure 41 comprenant une ou plusieurs espèces d’aluminures, ou au moins une couche oxyde 42 comprenant une ou plusieurs espèces d’oxydes métalliques, ou une combinaison de telles couches. - The gas mixture injection step 3 is carried out by circulating through the enclosure 2 a flow of gaseous mixture having a flow rate of between 6 and 15 times the volume of the enclosure 2 per hour. The invention advantageously applies to a part 1 comprising a coating 4 comprising at least one aluminide layer 41 comprising one or more species of aluminides, or at least one oxide layer 42 comprising one or more species of metal oxides, or a combination of such layers.
Au cours de ce procédé, le ou les gaz halogénés réagissent avec les couches aluminures 41 et les couches oxydes 42 selon les réactions suivantes :  During this process, the halogenated gas or gases react with the aluminide layers 41 and the oxide layers 42 according to the following reactions:
Pour les espèces aluminures : HX(g) + ScAl(s) -> AlX3(g) + H2 + Sc(s)  For aluminide species: HX (g) + ScAl (s) -> AlX3 (g) + H2 + Sc (s)
Pour les espèces oxydes : HX(g) + MxOy(s) -> MxX (g) + H20(g)  For oxide species: HX (g) + MxOy (s) -> MxX (g) + H20 (g)
Avec X une espèce halogène, H de l’hydrogène, M un métal, O de l’oxygène, Al de l’aluminium, Sc un métal de transition.  With X a halogen species, H of hydrogen, M a metal, O of oxygen, Al of aluminum, Sc a transition metal.
Par exemple, X peut être du fluor, du chlore, du brome ou de l’iode et Sc peut être du Nickel, du cobalt, du titane ou tout autre métal de transition.  For example, X can be fluorine, chlorine, bromine or iodine and Sc can be Nickel, cobalt, titanium or any other transition metal.
Préférentiellement, l’espèce halogène X comporte du fluor, par exemple sous forme d’acide fluorhydrique. Le fluor présente une réactivité importante et permet une réaction plus rapide qu’avec l’utilisation d’autres éléments halogénés.  Preferably, the halogen species X comprises fluorine, for example in the form of hydrofluoric acid. Fluorine has a high reactivity and allows a faster reaction than with the use of other halogenated elements.
Il est entendu que ce type de réaction est un exemple à titre illustratif, et le procédé peut s’appliquer à tout composé aluminure ou aluminure modifié, et non uniquement l’aluminure de nickel.  It is understood that this type of reaction is an example by way of illustration, and the process can be applied to any aluminide or modified aluminide compound, and not only nickel aluminide.
On peut citer notamment les aluminures de nickel, les aluminures modifiés platine, les aluminures de cobalt, les aluminures de titane, ...  Mention may in particular be made of nickel aluminides, modified platinum aluminides, cobalt aluminides, titanium aluminides, etc.
Les couches du revêtement à base d’aluminures 41 et les couches du revêtement à base d’oxydes métallique 42 sont donc éliminées en une phase de traitement thermochimique, ce qui permet de décaper la pièce 1 et de révéler le substrat 5 sans requérir à une étape de bain chimique ni de sablage pour éliminer ce type de couches.  The layers of the coating based on aluminides 41 and the layers of the coating based on metallic oxides 42 are therefore eliminated in a thermochemical treatment phase, which makes it possible to strip the part 1 and to reveal the substrate 5 without requiring a chemical bath or sandblasting step to remove this type of layer.
Le procédé de décapage est donc simplifié et rendu plus sûr, le substrat 5 n’étant pas dégradé lors du procédé et les opérateurs n’étant pas mis en contact avec des produits dangereux.  The pickling process is therefore simplified and made safer, the substrate 5 not being degraded during the process and the operators not being brought into contact with dangerous products.
L’enceinte 2 est traversée en continu par un flux de mélange gazeux 3 qui présente un débit représentant entre 6 et 15 fois le volume de l’enceinte 2 par heure, préférentiellement entre 8 et 12 fois le volume de l’enceinte 2 par heure. Cela permet d’apporter la quantité de gaz actif nécessaire et suffisante pour opérer une réaction efficace sur la totalité de pièce dans l’enceinte (en termes de volume ou de surface). The enclosure 2 is continuously traversed by a flow of gaseous mixture 3 which has a flow rate representing between 6 and 15 times the volume of the enclosure 2 per hour, preferably between 8 and 12 times the volume of the enclosure 2 per hour . This makes it possible to supply the quantity of active gas necessary and sufficient to operate an effective reaction on the entire part in the enclosure (in terms of volume or surface).
Le débit de mélange gazeux 3 peut être adapté en fonction de la quantité de pièces 1 à traiter, ou de la surface totale à décaper.  The gas mixture flow 3 can be adapted as a function of the quantity of parts 1 to be treated, or the total surface to be stripped.
A titre d’exemple, le débit en gaz halogéné peut être compris entre 6L/min et 10L/min, et le débit en dihydrogène peut être compris entre 130 L/min et 160 L/min pour une enceinte ayant un volume de l’ordre d’1 m3 dans laquelle sont placées 45 pièces 1.  For example, the flow rate of halogenated gas can be between 6L / min and 10L / min, and the flow rate of dihydrogen can be between 130 L / min and 160 L / min for an enclosure having a volume of order of 1 m3 in which 45 pieces are placed 1.
La phase de chauffage comprend une montée en température, un palier de maintien en température et un refroidissement.  The heating phase includes a rise in temperature, a temperature holding level and a cooling.
Le palier de maintien en température peut durer entre 2 heures et 10 heures, préférentiellement entre 3,5 heures et 5,5 heures (comprendre 3 heures et 30 minutes ou 5 heures et 30 minutes).  The temperature holding stage can last between 2 hours and 10 hours, preferably between 3.5 hours and 5.5 hours (include 3 hours and 30 minutes or 5 hours and 30 minutes).
La température du palier de maintien est supérieure à 1000°C, préférentiellement supérieure à 1030°C, par exemple comprise entre 1035°C et 1055°C.  The temperature of the holding bearing is greater than 1000 ° C, preferably greater than 1030 ° C, for example between 1035 ° C and 1055 ° C.
De tels intervalles de température ont pour effet d’augmenter l’efficacité du procédé de décapage et nettoyage par rapport à un nettoyage simple des oxydes, comme c’est le cas lors de procédés de FIC standard. En effet, la cinétique des réactions mises en jeu, soit avec les oxydes soit avec les alliages NiAl ou NiAIPt du revêtement à décaper, est fonction de la température.  Such temperature intervals have the effect of increasing the efficiency of the pickling and cleaning process compared to a simple cleaning of oxides, as is the case with standard FIC processes. In fact, the kinetics of the reactions involved, either with the oxides or with the NiAl or NiAIPt alloys of the coating to be stripped, is a function of the temperature.
Avantageusement, une étape de sablage peut être réalisée préalablement au traitement thermochimique. Cela permet d’éliminer des résidus de combustion, par exemple de calamine, formées en surface du revêtement 4 au cours du fonctionnement de la turbomachine, ainsi que d’éventuelles couches de barrières thermiques 43 en céramique et les couches passivantes 44 qui les recouvrent, par exemple des couches comprenant du calcium-magnésium-aluminosilicate.  Advantageously, a sandblasting step can be carried out prior to the thermochemical treatment. This eliminates combustion residues, for example of scale, formed on the surface of the coating 4 during the operation of the turbomachine, as well as any thermal barrier layers 43 made of ceramic and the passivating layers 44 which cover them, for example layers comprising calcium-magnesium-aluminosilicate.
L’étape de sablage permet ainsi de révéler les couches aluminure 41 et les couches oxydes 42 du revêtement, qui seront éliminées en une phase de cycle thermochimique. L’étape de sablage réalisée en amont ne représente ainsi pas de danger pour le substrat 5. The sandblasting step thus makes it possible to reveal the aluminide layers 41 and the oxide layers 42 of the coating, which will be eliminated in a thermochemical cycle phase. The sanding step carried out upstream does not therefore represent a danger for the substrate 5.
Après le sablage préalable, une ou plusieurs pièces 1 sont placées dans une enceinte 2 fermée, préférentiellement sur une grille, permettant une meilleure circulation du mélange gazeux 3 le long de toute la surface de la ou les pièces 1 , ce qui améliore le traitement.  After the preliminary sanding, one or more parts 1 are placed in a closed enclosure 2, preferably on a grid, allowing better circulation of the gas mixture 3 along the entire surface of the part or parts 1, which improves the treatment.
Le mélange gazeux 3 est ensuite injecté dans l’enceinte 2.  The gas mixture 3 is then injected into the enclosure 2.
Optionnellement, le mélange gazeux 3 comporte en outre un composant ou une combinaison de composants parmi les composants suivants :  Optionally, the gas mixture 3 also comprises one component or a combination of components from the following components:
- acide fluorhydrique H F,  - hydrofluoric acid H F,
- acide chlorhydrique HCl,  - hydrochloric acid HCl,
- acide bromhydrique H Br,  - hydrobromic acid H Br,
- acide iodhydrique Hl.  - hydroiodic acid Hl.
Le mélange gazeux 3 peut en outre avantageusement comporter du dihydrogène.  The gas mixture 3 can also advantageously comprise dihydrogen.
Optionnellement mais avantageusement, le mélange gazeux 3 comporte en outre un gaz inerte, par exemple de l’hélium, du néon, de l’Argon, du krypton, du xénon ou du radon, ou une combinaison de ces éléments.  Optionally but advantageously, the gas mixture 3 also comprises an inert gas, for example helium, neon, Argon, krypton, xenon or radon, or a combination of these elements.
Cela permet de transporter les gaz réactifs et de contribuer à l’homogénéisation du mélange gazeux 3 dans l’enceinte 2 du four.  This makes it possible to transport the reactive gases and to contribute to the homogenization of the gas mixture 3 in the enclosure 2 of the oven.
La concentration de gaz halogéné dans le mélange gazeux 3 est avantageusement compris entre 4% et 12%, préférentiellement entre 6% et 8%, par exemple en pourcentages massiques.  The concentration of halogenated gas in the gas mixture 3 is advantageously between 4% and 12%, preferably between 6% and 8%, for example in mass percentages.
Cela permet de contrôler la quantité du gaz réactif introduit dans l’enceinte ainsi optimiser la réaction en surface des pièces.  This allows the amount of reactive gas introduced into the enclosure to be controlled, thereby optimizing the surface reaction of the parts.
Cela permet d’optimiser le processus de manière à éviter que les réactions ne deviennent trop lentes si les concentrations sont faibles, ou au contraire éviter que des concentrations fortes n’entraînent une saturation de l’atmosphère qui nuirait à l’efficacité des réactions et entraînerait un risque de contamination du matériau de base (fluor, chlore ,...).  This makes it possible to optimize the process in such a way as to prevent the reactions from becoming too slow if the concentrations are low, or on the contrary to prevent high concentrations from causing saturation of the atmosphere which would adversely affect the efficiency of the reactions and would cause a risk of contamination of the base material (fluorine, chlorine, ...).
La concentration en gaz halogénés a notamment une influence sur la vitesse de diffusion des espèces réactifs, avec la température. Optionnellement, l’alimentation de l’enceinte 2 en mélange gazeux 3 suit un cycle séquentiel, et présente : The concentration of halogenated gases has in particular an influence on the rate of diffusion of the reactive species, with the temperature. Optionally, the supply of enclosure 2 with gas mixture 3 follows a sequential cycle, and presents:
- une phase d’injection, au cours de laquelle le mélange gazeux 3 est injecté dans l’enceinte 2,  - an injection phase, during which the gas mixture 3 is injected into the enclosure 2,
- une phase de traitement au cours de laquelle le mélange gazeux 3 est maintenu dans l’enceinte 2 au cours du chauffage de manière à réagir avec le revêtement 4, et  a treatment phase during which the gas mixture 3 is maintained in the enclosure 2 during heating so as to react with the coating 4, and
- une phase de purge au cours de laquelle les réactifs de traitement sont évacués avec le mélange gazeux 3 contenu dans l’enceinte 2.  - a purge phase during which the treatment reagents are removed with the gas mixture 3 contained in the enclosure 2.
Consécutivement à la phase de purge, une nouvelle phase d’injection est réalisée et un cycle d’alimentation recommence tant que le traitement thermochimique n’est pas terminé.  Following the purge phase, a new injection phase is carried out and a feeding cycle starts again until the thermochemical treatment is not completed.
Le traitement thermochimique peut être réalisé à pression atmosphérique, ou préférentiellement sous pression réduite (ou basse pression, c’est-à-dire inférieure à 300 mbar). Le traitement sous pression réduite permet un gain de temps, demande moins de gaz et est plus efficace car les gaz peuvent pénétrer plus rapidement et de façon très efficace dans des criques, fissures et cavités même si elles sont trop étroites et profondes.  The thermochemical treatment can be carried out at atmospheric pressure, or preferably under reduced pressure (or low pressure, that is to say less than 300 mbar). Treatment under reduced pressure saves time, requires less gas and is more efficient because gases can penetrate cracks, cracks and cavities more quickly and very effectively, even if they are too narrow and deep.

Claims

REVENDICATIONS
1 . Procédé de décapage d’une pièce (1 ) de turbomachine, comprenant les étapes suivantes : 1. Method for pickling a part (1) of a turbomachine, comprising the following steps:
- Positionnement de la pièce dans une enceinte (2) fermée, - Positioning of the part in a closed enclosure (2),
- Injection d’un mélange gazeux (3) dans l’enceinte (2), le mélange gazeux (3) comprenant un gaz halogéné,  - Injection of a gas mixture (3) into the enclosure (2), the gas mixture (3) comprising a halogenated gas,
- Chauffage de l’enceinte (2),  - Heating of the enclosure (2),
le procédé étant caractérisé en ce que : the method being characterized in that:
- le mélange gazeux comprend en outre du dihydrogène, the gaseous mixture also comprises dihydrogen,
- l’étape de chauffage est réalisée à une température supérieure à 1000° C et - the heating step is carried out at a temperature above 1000 ° C and
- l’étape d’injection de mélange gazeux (3) est réalisée en faisant circuler à travers l’enceinte (2) un flux de mélange gazeux (3) présentant un débit compris entre 6 et 15 fois le volume de l’enceinte (2) par heure. - the gas mixture injection step (3) is carried out by causing a flow of gas mixture (3) to flow through the enclosure (2) having a flow rate of between 6 and 15 times the volume of the enclosure ( 2) per hour.
2. Procédé de décapage selon la revendication 1 , dans lequel le mélange gazeux comporte du fluor.  2. The pickling method according to claim 1, wherein the gas mixture comprises fluorine.
3. Procédé de décapage selon l’une des revendications 1 ou 2, dans lequel la température de l’étape de chauffage est supérieure à 1030° C.  3. Pickling method according to one of claims 1 or 2, wherein the temperature of the heating step is greater than 1030 ° C.
4. Procédé de décapage selon l’une des revendications 1 à 3, dans lequel le mélange gazeux (3) comporte en outre un gaz inerte, par exemple de l’argon.  4. pickling method according to one of claims 1 to 3, wherein the gas mixture (3) further comprises an inert gas, for example argon.
5. Procédé de décapage selon l’une des revendications 1 à 4, dans lequel une concentration du gaz halogéné dans le mélange gazeux (3) est comprise entre 4% et 12% en pourcentages massiques, préférentiellement entre 6% et 8% en pourcentages massiques.  5. pickling method according to one of claims 1 to 4, wherein a concentration of the halogenated gas in the gas mixture (3) is between 4% and 12% in mass percentages, preferably between 6% and 8% in percentages mass.
6. Procédé de décapage selon l’une des revendications 1 à 5, dans lequel le débit du flux de mélange gazeux (3) est compris à entre 8 et 12 fois le volume de l’enceinte (2) par heure.  6. Pickling method according to one of claims 1 to 5, wherein the flow rate of the gas mixture flow (3) is between 8 and 12 times the volume of the enclosure (2) per hour.
7. Procédé de décapage selon l’une des revendications 1 à 6, dans lequel une pression totale dans l’enceinte (2) est sensiblement égale à la pression atmosphérique.  7. The pickling method according to one of claims 1 to 6, wherein a total pressure in the enclosure (2) is substantially equal to atmospheric pressure.
8. Procédé de décapage selon l’une des revendications 1 à 6, dans lequel une pression totale dans l’enceinte (2) est inférieure à la pression atmosphérique. 8. pickling method according to one of claims 1 to 6, wherein a total pressure in the enclosure (2) is less than atmospheric pressure.
9. Procédé de décapage selon l’une des revendications 1 à 8, ledit procédé comprenant uniquement les étapes de : 9. pickling method according to one of claims 1 to 8, said method comprising only the steps of:
- Sablage de la pièce (1 ),  - Sandblasting of the part (1),
- Positionnement de la pièce (1 ) sablée dans l’enceinte (2) fermée,  - Positioning of the sanded part (1) in the closed enclosure (2),
- Injection du mélange gazeux (3) dans l’enceinte (2) et - Injection of the gas mixture (3) into the enclosure (2) and
- Chauffage de l’enceinte (2).  - Heating of the enclosure (2).
EP19829275.7A 2018-11-14 2019-11-14 Method for pickling a turbomachine component Pending EP3880870A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR1871525A FR3088346A1 (en) 2018-11-14 2018-11-14 PROCESS FOR STRIPPING A TURBOMACHINE PART
PCT/FR2019/052707 WO2020099794A1 (en) 2018-11-14 2019-11-14 Method for pickling a turbomachine component

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US11549371B2 (en) 2023-01-10
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WO2020099794A1 (en) 2020-05-22

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