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.

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• 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)

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• 2018
  • 2018-11-14 FR FR1871525A patent/FR3088346A1/fr active Pending
• 2019
  • 2019-11-14 WO PCT/FR2019/052707 patent/WO2020099794A1/fr unknown
  • 2019-11-14 CN CN201980074962.2A patent/CN113015822A/zh active Pending
  • 2019-11-14 EP EP19829275.7A patent/EP3880870A1/fr active Pending
  • 2019-11-14 US US17/293,691 patent/US11549371B2/en active Active

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