Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22C—FOUNDRY MOULDING
  • B22C9/00—Moulds or cores; Moulding processes
  • B22C9/10—Cores; Manufacture or installation of cores
• • 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
  • F01D5/12—Blades
  • F01D5/28—Selecting particular materials; Particular measures relating thereto; Measures against erosion or corrosion
  • F01D5/288—Protective coatings for blades
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22C—FOUNDRY MOULDING
  • B22C23/00—Tools; Devices not mentioned before for moulding
  • B22C23/02—Devices for coating moulds or cores
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22C—FOUNDRY MOULDING
  • B22C3/00—Selection of compositions for coating the surfaces of moulds, cores, or patterns
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22C—FOUNDRY MOULDING
  • B22C9/00—Moulds or cores; Moulding processes
  • B22C9/12—Treating moulds or cores, e.g. drying, hardening
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D19/00—Casting in, on, or around objects which form part of the product
  • B22D19/08—Casting in, on, or around objects which form part of the product for building-up linings or coverings, e.g. of anti-frictional metal
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D27/00—Treating the metal in the mould while it is molten or ductile ; Pressure or vacuum casting
  • B22D27/18—Measures for using chemical processes for influencing the surface composition of castings, e.g. for increasing resistance to acid attack
• • 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
  • C23F11/00—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent
  • C23F11/08—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids
  • C23F11/18—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids using inorganic inhibitors
• • 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
  • F05D2230/90—Coating; Surface treatment
• • 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
  • F05D2300/00—Materials; Properties thereof
  • F05D2300/10—Metals, alloys or intermetallic compounds
  • F05D2300/13—Refractory metals, i.e. Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W
  • F05D2300/132—Chromium
• • 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
  • F05D2300/00—Materials; Properties thereof
  • F05D2300/10—Metals, alloys or intermetallic compounds
  • F05D2300/13—Refractory metals, i.e. Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W
  • F05D2300/135—Hafnium
• • 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
  • F05D2300/00—Materials; Properties thereof
  • F05D2300/10—Metals, alloys or intermetallic compounds
  • F05D2300/14—Noble metals, i.e. Ag, Au, platinum group metals
  • F05D2300/143—Platinum group metals, i.e. Os, Ir, Pt, Ru, Rh, Pd
• • 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
  • F05D2300/00—Materials; Properties thereof
  • F05D2300/10—Metals, alloys or intermetallic compounds
  • F05D2300/15—Rare earth metals, i.e. Sc, Y, lanthanides
• • 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
  • F05D2300/00—Materials; Properties thereof
  • F05D2300/10—Metals, alloys or intermetallic compounds
  • F05D2300/17—Alloys
  • F05D2300/175—Superalloys
• • 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
  • F05D2300/00—Materials; Properties thereof
  • F05D2300/20—Oxide or non-oxide ceramics
  • F05D2300/22—Non-oxide ceramics
  • F05D2300/222—Silicon
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
  • Y02T50/00—Aeronautics or air transport
  • Y02T50/60—Efficient propulsion technologies, e.g. for aircraft

Definitions

• the invention relates to the protection against oxidation and/or corrosion of at least one hollow internal zone of a turbomachine part made of a superalloy.
• a method of protection is thus concerned, as well as a monocrystalline part of a gas turbine engine for an aircraft made of a superalloy, and a foundry core which can be used to provide the surface of said hollow internal zone of the part with the material necessary for protection against oxidation and/or corrosion.
• a superalloy, or high performance alloy is an alloy which exhibits several high characteristics in mechanical strength, resistance to thermal creep deformation, surface stability and resistance to corrosion. or oxidation.
• Its crystalline structure is typically face-centered cubic austenitic.
• a superalloy includes:
• a gamma austenitic matrix in which Ni can be substituted by Co, Cr, Mo, W, as well as by Nb, Al, Ti, Ta, Fe
• Such alloys are Hastelloy, Inconel, Waspaloy, Rene, Incoloy, MP98T, TMS alloys and single crystal CMSX alloys.
• FIG. 1 illustrates a curve of stress (MPa) as a function of temperature (°C) for various materials which can be used on a gas turbine engine for aircraft, including superalloys.
• Nickel-based (Ni) superalloys are particularly targeted in this text.
• a nickel-based alloy is defined as an alloy in which the mass percentage of nickel is predominant.
• a nickel-based superalloy comprising, in mass percentages, 5.0 to 6.0% aluminum, 6.0 to 9.5% tantalum, 0 to 1.50% titanium, 8.0 10.0% cobalt, 6.0-7.0% chromium, 0.30-0.90% molybdenum, 5.5-6.5% tungsten, 0-2.50% rhenium, 0.05 to 0.15% hafnium, 0.70 to 4.30% platinum, 0 to 0.15% silicon, the balance consisting of nickel and inevitable impurities. Unavoidable impurities are defined as elements which are not intentionally added to the composition and which are added with other elements.
• C carbon
• S sulfur
• nickel-based superalloy includes, in mass percentages, 6 to 8% aluminum, 12 to 15% cobalt, 4 to 8% chromium, 0 to 0.2% hafnium, 0.5 4% molybdenum, 3.5-6% rhenium, 4-6% tantalum, 1-3% titanium, 0-2% tungsten, 0-0.1% silicon, balance consisting of nickel and inevitable impurities.
• nickel-based superalloy comprising, in mass percentages, 4.0 to 5.5% rhenium, 3.5 to 12.5% cobalt, 0.30 to 1.50% molybdenum, 3.5-5.5% chromium, 3.5-5.5% tungsten, 4.5-6.0% aluminum, 0.35-1.50% titanium, 8.0-10 .5% tantalum, 0.15 to 0.30% hafnium, preferably 0.17 to 0.30% hafnium, 0.05 to 0.15% silicon, the remainder consisting of nickel and unavoidable impurities.
• the nickel-based superalloys targeted here are thus in particular those intended for the manufacture of single-crystal gas turbine components, such as fixed or moving blades.
• phases of superalloys include cobalt (Co) based superalloys.
• oxidation and/or corrosion behavior is a concern. Indeed, this involves chemical reactions of the alloying elements with oxygen to form new oxide phases, generally at the surface of the metal. If left unmitigated, oxidation and/or corrosion can degrade the alloy over time in a number of ways, including:
• the object of the invention is to provide a solution to this problem of behavior to oxidation and/or corrosion and of protection to be provided, in particular when the area to be protected is difficult to access.
• Hf hafnium
• Pt platinum
• a protection method is proposed here, to protect from oxidation and/or corrosion at least one hollow internal zone of a turbomachine part made of a superalloy, said at least one hollow internal zone having been formed, by means of at least one core in a material comprising a ceramic or metal or a hybrid metal and ceramic material, and limited by an outer surface which surrounds it, characterized in that before bringing the superalloy around the core, said outer surface is coated with a coating material comprising hafnium (Hf), and/or platinum (Pt), and/or chromium (Cr) and/or silicon (Si) and / or Yttrium (Y), or a mixture thereof.
• Hf hafnium
• Pt platinum
• Cr chromium
• Si silicon
• the coating material with which said outer surface is coated should favorably include:
• %m surface of the superalloy will indicate in this case the percentage by mass of the element in the total mass of superalloy thus loaded, after diffusion of the core towards the part of any or part of the reactive elements considered (Hf, Pt, Cr, Si, Y) or their at least partial mixture.
• the hafnium will be in the majority in %m in the possible at least nanometric layer containing hafnium, the same for platinum in the possible at least micrometric layer containing platinum, and for Cr and/or Si and/or Y in the or their layer.
• major means that it is the main constituent in %m in the layer. There may be more than 50%.
• its thickness may be less than 10 pm, or even less than 2 pm, and/or
• a layer of Si is provided, its thickness may be limited between 50 and 500 nm, and more preferably between 100 and 200 nm.
• the at least nanometric layer of hafnium, with which said outer surface is coated with the coating material is present, on the surface of the core, over a thickness of between 50 nm and 800 nm, or that hafnium is finally present between 0.3 and 15% m on the surface of the hollow internal zone of the part, in the superalloy, and/or
• the at least micrometric layer of platinum has a thickness of between 1 ⁇ m and 5 ⁇ m on the outer surface of the core, or that platinum is present between 15 and 60% m on the surface of the superalloy of the hollow internal zone of the final part , and or
• said at least one layer containing Cr and/or Si and/or Y has a thickness of between 30 nm and 10 ⁇ m, or else that chromium is present between 4 and 10% m at the surface of the superalloy of the hollow internal zone of the final part, or that silicon is present between 0.2 and 2% m on the surface of the superalloy of the hollow internal zone of the final part, or that Yttrium is present between 0.3 and 15% m on the surface of the superalloy of the hollow internal zone of the final part.
• the molten superalloy After having coated said outer surface of the core with the selected coating material, the molten superalloy will advantageously be brought into contact with said coated outer surface.
• part of the invention consists in using a core as mentioned above as a source of local modification of the chemistry of the alloy of the part, during a hollow part manufacturing process, advantageously according to the technique of molten wax (or lost wax), for example for forming cooling channels in a turbine engine blade for an aircraft.
• the cavity has a modified surface chemistry to increase the resistance to oxidation and corrosion of the material
• An objective here is thus to adapt the chemical composition of the superalloy on the surface in order to increase the resistance to the environment of an internal part of a hollow part, such as an internal cavity of a hollow turbine blade.
• nanometric nm; 10' 9 m
• micrometric or micronic pm; 10' 6 m
• thickness 0.5pm ⁇ e ⁇ 1000 pm.
• the coating of said outer surface is diffused between 800° C. and 1250° C., under high vacuum.
• a secondary vacuum is defined as a space where there is a pressure of less than 1 Pa, for example a pressure of approximately 10 ⁇ 1 Pa, to within 10%.
• the solution treatment will consist of heating the alloy to an appropriate temperature, maintaining this temperature long enough to cause the transformation of one or more constituents into a solid solution and cooling it fast enough to maintain these constituents in the solution.
• Possible heat treatments by subsequent precipitation already make it possible to control the release of these constituents in a natural (ambient temperature) or artificial (higher temperatures) state.
• the heating temperature of the superalloy for the solution treatment may be between 1100°C and 1375°C, depending on the alloy.
• solution heat treatment or solution heat treatment and hardening by precipitation ageing
• vanes fixed vanes, also called distributors or rectifiers, or moving vanes, in particular monocrystalline
• the superalloy be nickel-based.
• Nickel-based superalloys are indeed materials with an austenitic nickel-based matrix y (cubic with centered faces, therefore rather ductile) reinforced by hardening precipitates y' (of structure also CFC, but of ordered atomic nature) coherent with the matrix, that is to say having an atomic unit very close to this one.
• Compound y' of Nis(Al,Ti) formulation also has, due to its ordered nature, the remarkable property of having a mechanical resistance which increases with temperature up to approximately 800°C.
• the very strong coherence between y/y' confers a very high hot mechanical strength of nickel-based superalloys, which itself depends on the rate of hardening precipitates, which has led to:
• Nickel-based superalloys are currently the materials of choice for the hot parts of gas turbines, located in particular at the outlet of the combustion chamber. These materials have the advantages of combining both high creep resistance at high temperature and satisfactory resistance to oxidation and corrosion. Certain grades of nickel-based superalloys are thus used for the manufacture of fixed monocrystalline parts (such as distributors, ring segments) or mobile parts (such as turbine blades). The development of new superalloy grades with the aim of improving the mechanical properties at high temperature has led, over the years, to a significant reduction in the chromium content.
• the first generation AM1 alloy contained 7.5 wt% Cr
• the second generation CMSX-4 contained 6.5 wt%
• the corresponding third generation alloy, called CMSX-10 contained 2% m of Cr.
• Coatings can thus be used in order to improve the resistance to the oxidizing and/or corrosive environment of the combustion gases and to act as a thermal insulator in order to reduce the temperature seen by the superalloy substrate. This is particularly the case for the protection of the external parts of high-pressure turbine blades subjected to high stresses and temperatures.
• Coatings are usually made up of two layers.
• This layer can have two essential roles. The first is to protect the superalloy from oxidation and corrosion when using this coating alone. The second can be to ensure the adhesion of a second layer, generally called a thermal barrier, in the case of the use of a porous coating made up of a ceramic (for example of yttria zirconia).
• the aforementioned blades of aeronautical turbomachines can be hollow in order to be able to be cooled via the use of internal channels.
• the cooling channels can be obtained during the process for producing such a blade by the use of cores as proposed here, therefore containing at least one ceramic or metal or a hybrid material (composite) metal and ceramic, and having for example the shape of the cooling channels that one wishes to obtain.
• a core containing ceramic mention may be made of a core consisting mainly of amorphous silica ( ⁇ 80% by mass, to within 10%) and of cristobalite ( ⁇ 20% by mass, to within 10%). Different elements can be added depending on the desired properties such as alumina, zirconia, oxides or alkaline ions (CaCOs or MgO 2 ).
• Core heat treatment cycles can be performed such as debinding and sintering (T ⁇ 1200°C, within 10%).
• the metal of the part to be produced (here the selected superalloy) can then be poured into a mould, called a shell, so as to surround the core.
• the core is then dissolved, resulting in the expected part, such as a hollow blade structure.
• the expected part such as a hollow blade structure.
• its hollow parts are therefore exposed to the environment, and can be all the more sensitive to this environment if the alloy used for the manufacture of the blade is a latest generation alloy. containing a small amount of chromium.
• the invention also relates to a single-crystal part of a gas turbine engine for aircraft made of a superalloy, the part having:
• a coating limited to a non-zero depth less than or equal to 1 mm and comprising a concentration of hafnium, and/or platinum, and/or chromium and/ or silicon and/or yttrium, or a mixture thereof.
• the expected protection against oxidation and/or corrosion of this hollow internal zone may even be such that, in the final part obtained, the surface concentration of hafnium, and/or platinum, and/or chromium and/or silicon and/or Yttrium, or one of their mixtures in the superalloy, at the location of its outer coating, is limited at a non-zero depth, less than or equal to 0.5mm.
• the concentration, on the surface, in the superalloy be:
• said at least one hollow internal zone is an internal channel of the blade communicating with the outside and adapted to receive a fluid in order to cool the blade internally, and /Where
• FIG. 1 represents a curve of stress (MPa) as a function of temperature (°C) for various materials, including superalloys,
• FIG. 2 schematically represents, in a very local section, the diffusion of the coating applied to the core, which has therefore partially diffused in the zone (closest to the core/part interface) of the superalloy part
• FIG. 3 schematically represents part of a hollow aircraft turbine engine blade
• FIG. 4 represents a section along IV-IV of Figure 3
• FIG. 5 schematically represents a part of the core for the aforementioned hollow blade
• FIG. 6 schematically represents a variant of the enlarged surface area of the core illustrated in FIG. 5.
• the following description provided by way of non-limiting example, relates to a fixed or moving blade of a turbomachine turbine for an aircraft.
• such a blade can be obtained by casting a molten alloy in a mold using the lost wax casting technique.
• the internal core inside which the material of the blade, will comprise a ceramic material or metal or a hybrid metal and ceramic material.
• the core can thus have a porous structure and be made from a mixture consisting of a refractory filler in the form of particles and a more or less complex organic fraction forming a binder.
• a refractory filler in the form of particles and a more or less complex organic fraction forming a binder. Examples of compositions are given in patents EP 328 452, FR 2 371 257 or FR 2 785 836.
• a ceramic composition of the core mention may be made of a composition advantageously resulting from a mixture of silica powder, such as fused or vitreous silica, zircon and others, such as favorably cristobalite, alumina or zirconia.
• silica powder such as fused or vitreous silica, zircon and others, such as favorably cristobalite, alumina or zirconia.
• ceramic compositions can be found in US patent 5043014.
• it is a mixture of silica, zircon and cristobalite, particularly in respective proportions of 70-80/15-25/1-5 in % mass, even more particularly respective proportions in mass % of 77/20/3.
• Silica powder can have different grain sizes.
• a foundry core made of a refractory metal alloy, which may typically be a molybdenum alloy.
• a refractory metal alloy degrading easily under an oxidizing atmosphere and being soluble in the superalloy, it may therefore be necessary to protect the metal against oxidation and erosion. This protection will be favorably ensured by a metallic and/or ceramic multilayer coating with specific properties: antioxidant, anti-erosion, diffusion barrier... or other.
• silicides are recommended here (MoSi2, up to 1600°C or MoSi2 + Cr, Cr-B, Cr-B-Al, Sn-Al) and silicide complexes (SiCrFe, up to 1500°C).
• MoSi2 up to 1600°C or MoSi2 + Cr, Cr-B, Cr-B-Al, Sn-Al
• silicide complexes SiCrFe, up to 1500°C.
• ceramics Al2O3, ZrO2 + HfO2/ Y2O3, Al-Cr, Al-Si, Sn-Al
• metals Cr, Ni, noble metals, alloys.. .
• CVD Chemical Vapor Deposition -, PVD - Physical Vapor Deposition -, Plasma, etc.
• a bi-material hybrid core As an example of a bi-material hybrid core, mention may be made of a core consisting of a first material mainly based on silica/zircon (more precisely the core of the core) for example obtained by injection, machining or additive manufacturing and a second material containing the reactive elements (surface of the core) and which can be obtained by overinjection or additive manufacturing (projection of drops of material or fusion of wire through a heating nozzle).
• a core consisting of a first material mainly based on silica/zircon (more precisely the core of the core) for example obtained by injection, machining or additive manufacturing and a second material containing the reactive elements (surface of the core) and which can be obtained by overinjection or additive manufacturing (projection of drops of material or fusion of wire through a heating nozzle).
• the invention therefore consists in having used a core coated with reactive elements as a source of local modification of the chemistry of the superalloy, the objective having been to adapt the chemical composition of the superalloy on the surface in order to increase the resistance to the environment of the internal part of the part concerned: the internal cavity(ies) of a blade, in the preferred example selected.
• the core 20 itself, its core 24 therefore contains a ceramic or metal or a metal/ceramic hybrid material.
• ceramic composition, metallic composition and hybrid (or bi-material) ceramic/metallic composition of the core 24 of the core 20 have been presented above and are among the most appropriate.
• a notable increase in the surface resistance to the environment of the final part 2 (see FIGS. 2-4), therefore of the chemistry surface of the superalloy 40 which constitutes it (essentially; see FIG. 2), was noted by coating the outer surface of the core 20 with, as outer coating 24, a material comprising (possibly with a mixture of the elements below) :
• Hf hafnium
• the thickness e1 of the Hf layer is 20 nm ⁇ e1 ⁇ 900 nm , and even either 50 nm ⁇ e1 ⁇ 500 nm, and/or
• the thickness e2 of the Pt layer be 1 pm ⁇ e2 ⁇ 15pm, and even be 1 pm ⁇ e2 ⁇ 5pm.
• Depositing between 1 ⁇ m and 5 ⁇ m platinum and 0.5 ⁇ m of Hf (within 10%) has proven to be a particularly relevant solution, given the intended goals.
• the Pt and/or: Hf, possibly Cr, Si, Y layers or elements can be produced in the same deposition machine and be deposited by one physical vapor phase (PVD) processes such as: EBPVD, Joule evaporation, pulsed laser ablation or cathode sputtering,
• PVD physical vapor phase
• the Pt layer or element can be deposited by electrolytic deposition on condition that the composition of the core is doped with electrically conductive elements, such as metal or carbon.
• Hf and/or Cr, Si or Y layers or elements can be deposited by Chemical vapor deposition, in French chemical vapor deposition; CVD (PECVD, LPCVD, UHVCVD, APCVD, ALCVD, UHVCV).
• CVD PECVD, LPCVD, UHVCVD, APCVD, ALCVD, UHVCV.
• a diffusion treatment can be carried out in order to cause its aforementioned coating material(s) to diffuse into the core, and thus promote the supply profitable of all or part of these elements. Provision can be made for this diffusion treatment in the core to be carried out during the dissolution of the superalloy, which can take place during a heat treatment.
• the temperatures to promote the diffusion of the aforementioned reactive elements Pt and/or Hf, Cr, Si, Y will be favorably between 800° C. and 1250° C., under secondary vacuum, typically 10' 6 X 10 5 Pa, at 10% close.
• This casting of the superalloy of the part to be manufactured around the core could be favorably followed by a heat treatment in order to best promote the diffusion of the coating component(s) of the core, shown schematically in FIGS. 5-6, towards the superalloy of the piece, marked 2 in the illustration figures.
• the conditions may be the same as above: between 800° C. and 1250° C., to within 10%, under secondary vacuum, typically 10 ⁇ 1 Pa, to within 10%.
• FIG. 2 schematically illustrates the effect of the enrichment/diffusion on the aforementioned coating 1, which coating has therefore, in the figure, partially diffused in the upper zone (closest to the internal surface 2a) of the part 2 in superalloy.
• a first layer 4 of the coating 1, not or relatively little diffused, consisting very mainly of the contribution or enrichment element(s) in Pt and/or Hf, Cr, Si, Y transmitted to the part 2 during the casting of the superalloy 40 on the core 20 coated in whole or in part with these same elements (identified globally 22 in FIG. 5 or 6),
• the first heat treatment (T) may be a treatment for homogenizing the microstructure, the purpose of which is to dissolve the y′ phase precipitates and to eliminate the y/y′ eutectic phases or to significantly reduce their volume fraction.
• This treatment is carried out at a temperature above the solvus temperature of the y' phase and below the starting melting temperature of the superalloy (Tsolidus). Quenching can then be carried out at the end of this first heat treatment to obtain a fine and homogeneous dispersion of the precipitates y′.
• Tempering heat treatments can then be carried out in two stages, at temperatures below the solvus temperature of the y' phase: During a first stage (R1 ), to enlarge the y' precipitates and obtain the desired size , then during a second step (R2), to increase the volume fraction of this phase to about 70% at room temperature.
• FIG. 3 schematizes an example of a hollow blade, of the “bathtub” type, but the presence or absence of such a “bathtub” (cavity at the top of the blade open radially outwards) is irrelevant. It is on the other hand a hollow blade 2. In the figure, one can identify the foot 8 of the blade by which it is mounted on a turbine rotor, the platform 9 and the blade 10. The blade 10 is hollow (see section in FIG. 4) and comprises at its top opposite to the platform, the bath 7.
• the bath is delimited laterally by the wall of the blade and the bottom is formed by a wall 11 of the bottom of the bath , perpendicular to the radial axis of the blade.
• This bottom wall 11 which can be seen in section in FIG. 4 is traversed by orifices 12 which communicate with the internal cavities 13, 14 of the blade in order to evacuate part of the cooling fluid from the latter.
• This fluid is itself discharged into the stream of hot gas by the gap existing between the top and the annular surface of the stator located radially opposite.
• the solution of the invention will therefore have made it possible to protect the internal surfaces 2a of these cavities 13, 14 by having locally enriched in Pt and/or Hf, possibly Cr, and/or Si, and/or Y, the internal surface 2a of the superalloy 40 in which the blade 2, and in this case at least the hollow blade 10, is made.

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• 2020
  • 2020-08-06 FR FR2008333A patent/FR3113254B1/fr active Active
• 2021
  • 2021-08-05 WO PCT/FR2021/051444 patent/WO2022029388A1/fr unknown
  • 2021-08-05 US US18/040,767 patent/US20230304409A1/en active Pending
  • 2021-08-05 CN CN202180052990.1A patent/CN115989102A/zh active Pending
  • 2021-08-05 EP EP21762511.0A patent/EP4192635A1/de active Pending

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