WO2015006330A1 - Procédés de fabrication de revêtements d'aluminure par co-dépôt d'aluminium et d'un ou plusieurs éléments réfractaires et leur utilisation dans des systèmes de barrière thermique pour protéger des substrats contenant du métal dans des environnements à haute température - Google Patents

Procédés de fabrication de revêtements d'aluminure par co-dépôt d'aluminium et d'un ou plusieurs éléments réfractaires et leur utilisation dans des systèmes de barrière thermique pour protéger des substrats contenant du métal dans des environnements à haute température Download PDF

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Publication number
WO2015006330A1
WO2015006330A1 PCT/US2014/045761 US2014045761W WO2015006330A1 WO 2015006330 A1 WO2015006330 A1 WO 2015006330A1 US 2014045761 W US2014045761 W US 2014045761W WO 2015006330 A1 WO2015006330 A1 WO 2015006330A1
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Prior art keywords
coating
substrate
aluminide
aluminum
refractory
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PCT/US2014/045761
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English (en)
Inventor
Marc E. SUNESON
Bernard R. Rose
Randal E. WATKINS
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Sifco Industries, Inc.
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Publication of WO2015006330A1 publication Critical patent/WO2015006330A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C10/00—Solid state diffusion of only metal elements or silicon into metallic material surfaces
    • C23C10/06—Solid state diffusion of only metal elements or silicon into metallic material surfaces using gases
    • C23C10/14—Solid state diffusion of only metal elements or silicon into metallic material surfaces using gases more than one element being diffused in one step
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C10/00—Solid state diffusion of only metal elements or silicon into metallic material surfaces
    • C23C10/60—After-treatment
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
    • C23C28/30—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer
    • C23C28/32—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one pure metallic layer
    • C23C28/321—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one pure metallic layer with at least one metal alloy layer
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
    • C23C28/30—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer
    • C23C28/34—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates
    • C23C28/345—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates with at least one oxide layer
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
    • C23C28/30—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer
    • C23C28/34—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates
    • C23C28/345—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates with at least one oxide layer
    • C23C28/3455—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates with at least one oxide layer with a refractory ceramic layer, e.g. refractory metal oxide, ZrO2, rare earth oxides or a thermal barrier system comprising at least one refractory oxide layer

Definitions

  • the present invention relates to methods of making aluminide coatings that include at least one refractory element, e.g. one or more of Hf, Zr, Y, La, and/or Ce, and the use of these coatings in thermal barrier systems that help to protect metal- containing substrates in high temperature environments. More specifically, the present invention uses vapor phase coating techniques to incorporate constituents including Al and at least one refractory element into aluminide coatings in the presence of at least one reducing agent such as hydrogen and at least one halide compound in a multistage process.
  • at least one refractory element e.g. one or more of Hf, Zr, Y, La, and/or Ce
  • the present invention uses vapor phase coating techniques to incorporate constituents including Al and at least one refractory element into aluminide coatings in the presence of at least one reducing agent such as hydrogen and at least one halide compound in a multistage process.
  • the function of a gas turbine engine is to convert the energy in hydrocarbon fuel into useful work.
  • the gas turbine accomplishes this by compression of ambient air, addition of fuel to the compressed air, and combustion of the fuel/air mixture to drive a turbine.
  • Good design of the engine components promotes efficient conversion of the energy into useful work.
  • component design influences efficiency and power output to some degree
  • another primary factor affecting engine efficiency and power output is the difference between the ambient temperature of the incoming air and the combustion temperature.
  • the correlation of efficiency and power output to this temperature difference is a principle of basic thermodynamics. This means that greater efficiency and more power generally result with increasing operating temperature of the gas directed to the turbine. In practical terms, this means that the high temperature performance of the turbine components
  • Grain boundaries are a strengthening mechanism at room temperature but can be a source of failure at elevated temperatures in some current generation engines.
  • Development of specialized casting techniques to control and/or reduce grain boundaries in turbine airfoils has lead to columnar grained and single crystal airfoils.
  • the surfaces of the articles to be protected can be protected with an aluminum-containing protective coating whose surface oxidizes to form an aluminum oxide scale that inhibits further oxidation.
  • the protective coating therefore is sufficiently rich in Al to promote thermal growth of this oxide scale.
  • the scale is also referred to as a thermally grown oxide (TGO).
  • a ceramic topcoat is further applied over the aluminum-containing protective layer to help provide a thermal barrier that extends service life.
  • the TGO helps bond the ceramic topcoat to the protective coating.
  • the protective coating also referred to as a bond coat
  • the TGO layer, and the ceramic topcoat provide a Thermal Barrier Coating System (TBC) to protect the coated article.
  • TBC Thermal Barrier Coating System
  • the thermal barrier coating system Notwithstanding the protection provided by the thermal barrier coating system, the spallation and cracking of the thickening TGO scale layer often is the ultimate failure mechanism of conventional thermal barrier systems. Thus, improving the adhesion and integrity of the interfacial TGO scale is critical to the development of more reliable thermal barrier systems.
  • the aluminum-containing protective coating should oxidize to form a slow-growing, non- or less "rumpling,” nonporous TGO layer that adhere well to the protective coating and the ceramic topcoat.
  • a conventional bond coat is typically either an MCrAlY overlay (where M is Ni, Co, Fe, or combination of them) or a diffusion aluminide coating.
  • An MCrAlY overlay is generally applied by Electron Beam Physical Vapor Deposition (EB- PVD), High Velocity Oxy-Fuel (HVOF), Low Pressure Plasma Spray (LPPS) or Vacuum Plasma Spray (VPS).
  • EB- PVD Electron Beam Physical Vapor Deposition
  • HVOF High Velocity Oxy-Fuel
  • LPPS Low Pressure Plasma Spray
  • VPS Vacuum Plasma Spray
  • Diffusion aluminide coatings are generally formed by chemical vapor deposition (CVD), slurry coating, or by a diffusion process such as pack cementation, above-pack, or vapor (gas) phase deposition.
  • Diffusion aluminide coatings have particularly found widespread use as protective coatings for superalloy components of gas turbine engines due to: (1) the diffusion process is not a line-of-sight process allowing components with complex geometry or with internal surfaces to be coated; and (2) the diffusion process is generally cost-effective as compared with overlay process.
  • Refractory elements have been incorporated into aluminide coatings to improve the oxidation protection and adhesion properties provided by these coatings.
  • refractory elements that have been proposed for aluminide compositions include Hf, Zr, Y, La and/or Ce. With small additions of refractory elements to aluminide coatings, the adherence of the protective oxide scale to the coatings/alloys and the oxidation resistance of the coatings/alloys at high
  • hafnium decreases the propensity for rumpling when it diffuses into the coating and to the growing aluminum oxide increasing their creep resistance (Tolpygo et al., "Effect of Hf, Y and C in the underlying superalloy on the rumpling of diffusion aluminide coatings," Acta Materialia 56, Pages 489-499, 2008) as well as decreases the voids formed in the coating alloy at the metal-oxide interface during oxidation
  • U.S. Pat. No. 6,689,422 to Warnes et al. and U.S. Pat. No. 6,602,356 to Nagaraj et al. disclosed a CVD process to produce Platinum (Pt)-aluminide coatings with or without Hf addition.
  • U.S. Pat. No. 6,514,629 and U.S. Pat. No. 6,582,772 to Rigney et al. taught Hf-Si-modified Pt-aluminide coatings formed by the steps of providing a substrate, depositing layers containing the platinum, aluminum, hafnium, and silicon, and heating the layers so that the aluminum, hafnium, and silicon diffuse into the layer of platinum to form a protective layer.
  • Pack cementation, CVD and vapor phase process are three potential industrial diffusion coating processes for forming Hf-modified aluminide diffusion coatings.
  • the vapor phase process has the potential to offer many advantages.
  • the others have drawbacks.
  • pack cementation processes for both hafnium-modified aluminide and simple aluminide coatings share the same disadvantages, such as the need for an inert filler, the obstruction of cooling holes, and the embedded particles on the formed coating surface.
  • a significant disadvantage of using a CVD process to form a hafnium-modified aluminide coating is the considerable equipment cost.
  • alternative deposition methods such as vapor phase process, have been sought.
  • Hf-rich precipitated phases in the coating or on the coating surface such as HfC, Hf0 2j and Ni 2 AlHf etc, and furthermore, deteriorate the mechanical properties and the oxidation resistance of the aluminide coatings. Therefore, there is a need to develop low Hf content aluminide coatings whose application on turbine engine components, as either environmental coatings or the bond coat in a thermal barrier coating system, can significantly improve the gas-turbine performance.
  • the present invention provides strategies for making aluminide coatings and corresponding thermal barrier coating systems that protect metallic substrates in high temperature environments.
  • Vapor phase coating techniques are used in manner that efficiently and consistently incorporate refractory element content into the aluminide coatings.
  • the coatings show excellent adhesion to substrates as well as among layers of the coatings.
  • the coatings generally include a first coating comprising an aluminide that is formed on the substrate.
  • an oxide layer optionally is formed on this first coating.
  • a third coating comprising a ceramic optionally is then formed on the oxide.
  • An aspect of the present invention is that the aluminide coating deposition incorporates two heating stages.
  • a first heating stage occurs in the presence of a reducing gas under conditions that significantly increase or otherwise favor the formation of refractory element-containing species in the vapor phase.
  • the result is that surprisingly high levels of refractory element content can be incorporated into the resultant coatings in the second stage even when the donor materials contain relatively little refractory element content.
  • refractory element donor materials are used so efficiently that donor materials that include under 1 weight percent of refractory element donor compounds based on the total weight of aluminum sources can provide coatings with over 5 weight percent of the refractory element.
  • the process provides uniform coatings and is consistent from run to run.
  • the present invention may be used to apply coatings that protect any articles from a hostile operating environment.
  • the coatings protect against oxidation, hot corrosion, or other degradation in high temperature and/or chemically hostile environments.
  • a wide range of articles can be protected by these coatings, including turbine engine hot zone components, blades, vanes, combustors transition pieces, and the like.
  • the present invention relates to a method of forming an aluminide coating on a substrate, comprising the steps of:
  • At least one non-halide compound of at least one ref actory element e.g., hafnium (Hf), zirconium (Zr), yttrium (Y), lanthanum (La), cerium (Ce), or combinations thereof;
  • the present invention relates to a method of forming an aluminide coating on a substrate, comprising the steps of:
  • At least one non-halide compound of at least one refractory element such as one or more of hafnium (Hf), zirconium (Zr), yttrium (Y), lanthanum (La), cerium (Ce), or combinations thereof; iii) at least one aluminum source; and
  • FIG. 1 is a cross-sectional diagram of a metallic article with a thermal barrier coating of the present invention.
  • FIG. 1 schematically shows a cross-section of a portion of a coated article 10 manufactured in accordance with principles of the present invention.
  • article 10 is a constituent of a rocket, missile, aircraft, marine vessel, industrial facility, power utility, electric motor, chemical
  • article 10 is a constituent of a gas turbine engine such as being all or a portion of a high pressure turbine nozzle, low pressure turbine nozzle, turbine shroud, turbine blade, turbine vanes, and/or the like.
  • Article 10 can be a new part, a replacement part, or a repaired or refurbished part.
  • the article 10 can be casted, molded, machined, directionally solidified (DS), fabricated from a single crystal (SX), and/or fabricated in any other desired method.
  • the article 10 includes a body 11 that serves as a substrate for thermal barrier structure 12.
  • Body 11 includes a metallic composition that may be a pure metal, an intermetallic composition, an alloy, combinations of these and the like.
  • the body may contain a single phase or may contain multiple phases, e.g., an alloy matrix with intermetallic precipitates.
  • Body 11 may be amorphous, crystalline, and/or the like.
  • body 11 may also contain other constituents.
  • body 11 may be a composite that includes a metallic matrix and fibers (not shown) or the like.
  • body 11 includes nickel (Ni)-base, cobalt (Co)- base, titanium (Ti)-base, or iron (Fe)-base alloys.
  • Ni-base alloy means that Ni is the dominant element in the alloy. That is, more Ni is present than any other individual metal element in the alloy.
  • Co, Ti, and Fe are the dominant element in Co-base, Ti-base, and Fe-base alloys, respectively.
  • the alloy may include one or more other alloying elements such as chromium, aluminum, titanium, molybdenum, iron, manganese, tungsten, boron, niobium, tantalum, cobalt, silicon, rhenium, platinum, hafnium, zirconium, yttrium, combinations of these and the like.
  • alloys of nickel, cobalt, and/or nickel-iron are known as superalloys due to excellent mechanical strength, creep resistance and good surface stability at high
  • WASPALOYTM WASPALOYTM
  • RENETM e.g. RENE 41, RENE 80, RENE 95, and RENE 141
  • HAYNES-188 HAYNES-L605, INCOLOYTM
  • MP98T TMS
  • X40 MAR-M-247
  • CMSX-4 CMSX-6.
  • body 11 may include one or more layers.
  • a layer of platinum (not shown) may be deposited to form a surface layer on at least a portion of body 11.
  • the platinum can diffuse and incorporate into the protective coating 13 so that such separate layer of platinum may have dissipated at least into coating 13 after some period of use .
  • platinum can help to enhance the oxidation protection of body 1 1.
  • the incorporation of platinum also can enhance the mechanical properties of the aluminide coatings.
  • all or selected portion(s) of body 11 can be coated with a layer comprising Pt and heat treated.
  • the platinum can be deposited by any suitable method.
  • the platinum is deposited using an electroplating process and a suitable platinum source, such as a Pt P-salt with a formula of
  • the surface 25 of body 11 optionally may be textured to enhance the bonding of layer 13 to body 11.
  • the texture on surface 25 can be formed by a variety of techniques including molding the texture when body 11 is formed, embossing, chemical etching, sand blasting or otherwise abrading, laser ablation, combinations of these, and the like. When refurbishing components, sand blasting is a preferred technique to form the texture.
  • Thermal barrier structure 12 is provided on body 11.
  • Thermal barrier structure 12 includes protective coating 13, a thermally grown oxide layer 14, and a ceramic topcoat 15.
  • Protective coating 13 helps to protect body 11 against oxidation, particularly in high temperature environments (e.g., environments in which the temperature is above about 450°C, preferably above about 650°C, more preferably above about 850°C).
  • protective coating 13 comprises at least one aluminide.
  • an aluminide refers to a metal compound comprising aluminum at and least one other more electropositive metal element.
  • an aluminide is a metallic solid solution or an intermetallic composition. Examples of suitable aluminides include nickel aluminide, cobalt aluminide, combinations of these, and the like.
  • the protective coating 13 may be a single phase or may include one or more additional phases.
  • Aluminide compositions comprising at least (a) aluminum and (b) nickel and/or Co are preferred.
  • nickel aluminides and/or cobalt aluminides containing from about 45 to about 70 atomic percent Ni and/or Co based on the total amount of nickel, cobalt, and aluminum are preferred.
  • compositions provide a good balance between high temperature oxidation resistance and acceptable mechanical properties.
  • refractory elements also are incorporated into all or a portion of the aluminide content of coating 13.
  • a refractory element refers to a metal element having a melting point greater than about 795°C, preferably greater than 1 100°C, more preferably greater than 1850°C.
  • suitable refractory elements include one or more of Hf, Zr, Y, La, Ce, rhenium, osmium, and combinations of these. Of these, hafnium (Hf), zirconium (Zr), yttrium (Y), lanthanum (La), cerium (Ce), and combinations of these are preferred.
  • coating 13 comprises at least one of Hf, Zr, and/or Y, most preferably Hf.
  • the refractory element content offers excellent oxidation protection by minimizing the amount of oxidized scale and enhancing the adherence of the scale to the protective coating system 12.
  • the refractory elements may be present in coating 13 in a variety of forms including as metals, dopants, or non-metal compounds such as oxides, nitrides, carbides, combinations of these, or the like. These may be present in the same phase as other aluminide content or in separate phase(s).
  • coatings 13 may incorporate from 0.01 to 30 weight percent, preferably 0.1 to 20 weight percent, and more preferably 1 to 15 weight percent of refractory element(s) present in the surface of a coating as determined using SEM EDS spectroscopy techniques described below.
  • a refractory element is present in coating 13 as an oxide, halide, nitride, carbide, salt, or other compound, e.g., Hf0 or the like
  • the weight percent of refractory element in the coating is based on the amount of refractory element(s) that are present, not the compound(s) including the refractory element(s). For instance, if a particular coating includes 90 parts by weight of nickel aluminide and 10 parts by weight of Hf0 2 , the hafnium oxide content is 10% but the Hf content is 8.5% as determined by SEM EDS spectroscopy.
  • the weight percent of the refractory elements) in the coating is based upon the total weight of all elements within the surface areas analyzed using SEM EDS techniques.
  • a JEOL model 6610 scanning electron microscope equipped for energy dispersive spectroscopy (EDS) is used to determine the amount of refractory element(s) (such as hafnium) present in the surface of a coating, expressed as a weight percent.
  • EDS energy dispersive spectroscopy
  • 3 areas of a substrate are scanned at 20Kv, 5 OX magnification for 30 seconds from a working distance of 12 mm.
  • the weight percent of each area is then determined from the SEM EDS data.
  • the weight percent is taken as an average from the 3 areas. Scans may be taken on flat, concave, or convex areas such as the concave and convex airfoil as well as the buttress.
  • interdiffusion zone 9 is considered to be a portion of the coating 13 even though it extends downward into body 11.
  • Protective coatings 13 of the invention may include refractory element content within the outward growth portion 7 and/or the interdiffusion zone 9 of coating 13.
  • the coating 13 may have a thickness within a wide range.
  • the thickness mentioned here is the total thickness of the outward growth portion 7 and the interdiffusion zone 9.
  • a suitable thickness for coating 13 is similar to the thickness of conventional industrial coatings, typically about 25 to 125 micrometers (about 0.001- 0.005 inch).
  • Surface 27 of layer 13 optionally may be textured to enhance the adhesion of layer 13 to the oxide layer 14.
  • the texture can be formed in a variety of ways. In some modes of practice, layer 13 is formed as a conformal coating over surface 25 so that the texture of surface 25 (if any) is telegraphed to some degree to surface 27 so that direct texturing of surface 27 after surface 27 is formed can be avoided. Such direct texturing creates a risk of abrading through layer 13, losing protection in those through-abraded regions. In other modes of practice, surface 27 can be texturized after surface 27 is initially formed if desired.
  • protective coating 13 is formed using vapor phase coating techniques, including chemical (CVD) and/or physical (PVD) vapor deposition.
  • CVD chemical
  • PVD physical
  • the process will be described in the context of preparing Hf-containing aluminide coatings in which Hf is obtained from one or more sources including an oxide, nitride, and/or carbide of Hf such as Hf0 2 . It will be understood that coatings including one or more of the other refractory elements could be prepared by replacing all or a portion of the Hf sources described herein with comparable sources of one or more of the other refractory elements.
  • At least one substrate including at least body 11 is placed into a processing chamber and suitably supported so that contact between the substrate and generated vapors causes the desired coating to form under suitable conditions.
  • suitable conditions include carrying out the process at suitable temperatures in the presence of a reducing gas such as hydrogen.
  • a reducing gas such as hydrogen.
  • One suitable process chamber is described in WO 2010/135144, the entirety of which is incorporated herein by reference for all purposes.
  • the supports on which substrates are supported desirably are pre-conditioned in order to enhance coating
  • Pre-conditioning involves subjecting the supports to the coating process one or more times in the absence of any substrate(s).
  • the resultant aluminide coating may be heat treated to adjust the coating microstructure and composition distribution. Further background on using vapor phase coating techniques to form aluminide coatings are described in WO 2010/135144, the entirety of which is incorporated herein by reference for all purposes.
  • the aluminide coatings of the present invention are obtained from ingredients comprising at least one aluminum source, at least one non-halide compound of at last one refractory element, and a halide activator.
  • ingredients may be supplied in any convenient form such as a fine powder, nuggets, pellets, granules, flakes, or the like. These can be supplied in any convenient shape, such as irregular, dendritic, acicular, cubic, spheroidal, fibrous, combinations of these, and the like.
  • Aluminum used to form the aluminide content of coating 13 may be derived from a variety of sources.
  • the aluminum is obtained from commercially pure aluminum powder that may be mixed with an inert material such as alumina for easier handling and to reduce the risk of sintering.
  • an aluminum source includes 1.5 to 10 parts by weight of commercially pure aluminum powder per about 100 parts by weight of alumina.
  • the aluminum and alumina are powders of a size large enough to avoid undue sintering while small enough to react well. In one mode of practice 200 mesh aluminum powder and 100 mesh alumina would be suitable.
  • Aluminum sources include any aluminum containing material(s) suitable for use in physical or chemical vapor deposition in which an aluminum containing vapor is generated from the source and caused to form coating on the desired substrate.
  • other aluminum sources include Al-rich alloys and/or intermetallic compositions optionally containing other elements such as those other metals and refractory elements described herein with respect to forming aluminide compositions. Examples include Cr, Co, Ni, Fe, Mo, W, Mn, Ti, Y, Zr, Pt, Hf, combinations of these, or the like.
  • the Al content in such sources desirably is about 3 weight percent to about 99 weight percent, preferably from about 15 weight percent to about 50 weight percent based on the total weight of the source material. The remainder of the source may be one or more of the other elements described herein and/or compounds of such elements.
  • An exemplary alloy source includes from about 25 weight percent to 35 weight percent aluminum.
  • aluminum incorporated into aluminum sources desirably is obtained from natural resources containing very little if any sulfur in order to exclude sulfur as much as practical from coating 13. Sulfur may tend to segregate to surfaces and could then adversely impact the oxide layer to base metal adhesion.
  • a superalloy such as the Mar M 247 alloy with less than 1 PPM bulk sulfur by weight tends to form a very adherent aluminum oxide just from the ⁇ 5.0% Al present for base material strength.
  • Such a low sulfur alloy does not require the typical local enrichment of the component surface with aluminum using standard aluminide coating techniques.
  • More preferred aluminum sources include sufficiently limited amounts of sulfur (if any) such that the resultant layer 13 includes less than 500 ppm, preferably less than 100 ppm, and even less than 10 ppm sulfur on a weight basis.
  • Bauxite is a natural resource from which substantially sulfur-free aluminum can be obtained. Accordingly, aluminum sources derived from bauxite are preferred, particularly commercially pure aluminum powder.
  • Chromium ores are largely sulfide type ores which often include substantial trace amounts of sulfur even after extensive refining.
  • Aluminum donor materials containing chromium could include undue amounts of sulfur that could unduly contaminate the resultant aluminide coating. In many embodiments, therefore, it is preferred that chromium also is excluded from aluminum sources, and hence coating 13, as much as possible.
  • layer 13 includes less than 500 ppm, preferably less than 100 ppm, and even less than 10 ppm chromium on a weight basis.
  • the amount of aluminum source materials desirably is about 0.3 kg to about 7 kg per cubic foot of the internal volume of the processing chamber, preferably from about 2 kg to about 4 kg per cubic foot of the internal volume of the chamber. This does not include diluent material, such as alumina, if included.
  • the additional metal elements used to form the aluminide(s) may be introduced from one or more sources including from substrate body 11, from the aluminum source(s), and/or from one or more independent source(s). Such elements may then react with the aluminum to form one or more aluminides. For example, as aluminum is deposited onto body 11 to form layer 13, one or more metallic constituents of body 11 such as Ni may diffuse or otherwise be incorporated into layer 13. The nickel and aluminum react to form nickel aluminide. From one perspective, such a process can be viewed as emiching the surface of body 11 to form an aluminum rich region constituted by layer 13.
  • the refractory element(s) may be provided by one or more sources wherein at least a portion of at least one source, preferably substantially all of the source, includes a non-halide compound of the element such as a salt, a metallic compound, an oxide, other oxygen-containing compound, nitride, carbide, and/or the like.
  • a non-halide compound of the element such as a salt, a metallic compound, an oxide, other oxygen-containing compound, nitride, carbide, and/or the like.
  • At least 25 weight percent, preferably at least about 50 weight percent, more preferably substantially all of the refractory element source(s) are such compound(s).
  • Oxide sources are preferred.
  • a preferred Hf source is Hf0 2 .
  • using an oxide of Hf as a source provides excellent control over the Hf activity when using vapor phase techniques for co-deposition of Hf and aluminum.
  • the refractory element source(s) optionally may include one or more halides of a refractory element if desired.
  • halides include chlorides and fluorides of one or more refractory elements, including HfCl 4 , HfF 4 , combinations of these, and the like.
  • the amount of Hf source materials desirably is about 0.01 weight percent to about 10 weight percent, preferably about 0.05 weight percent to about 5 weight percent total amount of aluminum source materials, including diluent such as alumina, if any.
  • the lialide activator includes one or more halide containing compounds including covalent compounds and salts.
  • One function of the activator is to provide a chemical species which acts to help transfer the aluminum and/or hafnium from the source materials to the target.
  • the activator typically has a sufficiently high vapor pressure at typical coating temperatures that a reasonable reaction time can be achieved.
  • Suitable halide activators include A1F 3 , A1C1 3 , N3 ⁇ 4F, NH 4 C1, NaF, NaCl, KF, KC1.
  • Other activators include halide containing compounds such as CrF 2 , one or more fluorinated polymers such as polytetrafluoroethylene (PTFE available from E. I. DuPont de Nemours under the trade designation TEFLON), or the like. These preferably are present as a powder within the coating chamber. Vapor phase halides such as HF also may be introduced during the coating process.
  • AIF3 is a preferred activator that is preferably used in amounts of about 0.4 to
  • halide activators such as those noted are substituted for AIF 3 , these would be used in amounts sufficient to achieve an equivalent level of activator activity.
  • the activator materials are preferably supplied as fine powders having an average size less than 1 mm.
  • constituents comprising the one or more aluminum sources, one or more halide activators are placed into the bottom of the processing chamber in trays. Desirably, these are pre-mixed powders. Then, one or more refractory element sources are provided as powders and sprinkled on top of the mixture.
  • the aluminum source is obtained by mixing 5 parts by weight of commercially pure aluminum powder with 95 parts by weight of alumina. The aluminum source is pre-mixed with 3 to 10 parts by weight of A1F 3 per 100 parts by weight of aluminum powder and alumina. The refractory element source is 0.15 parts by weight of HfO 2 powder per 100 parts by weight of aluminum powder and alumina.
  • the substrate(s) to be coated are placed onto pre-conditioned supports such as a metal screen to that the substrates are out of contact with the solid coating materials during the coating process.
  • the distance between the substrates and the solid coating materials can be changed to adjust the thickness of the resulting coatings.
  • a typical distance is in the range from 9 cm to 20 cm.
  • the surface 25 of body 11 can be appropriately cleaned, activated, or otherwise treated. For instance, if body 11 is an original or replacement part, the surface can be cleaned. If body 11 is a used part that is being repaired, then a stripping process can be used to remove previous coatings. Stripping can be followed by a suitable surface cleaning operation.
  • the practice of the present invention removes at least some oxide from the surface(s) of body 11 during at least one incubation stage, as described below, and this helps to prepare body 11 as well.
  • a flow of an inert gas such as argon or nitrogen is initiated and used to purge air from the process chamber prior to heating. After the purge, the flow of inert gas is continued as the process chamber is heated to a temperature that is above the auto ignition temperature of hydrogen. In one mode of practice, the process chamber is heated to 1450°F under a flow of the inert gas. Once this temperature is reached, a flow of hydrogen and/or one or more other suitable reducing gases is introduced into the process chamber. The flow of the inert gas may be continued, reduced, or stopped. In one mode of practice, the flow of inert gas is stopped and a flow of substantially pure hydrogen is established.
  • an inert gas such as argon or nitrogen is initiated and used to purge air from the process chamber prior to heating. After the purge, the flow of inert gas is continued as the process chamber is heated to a temperature that is above the auto ignition temperature of hydrogen. In one mode of practice, the process chamber is heated to 1450°F under a flow of the inert gas
  • the water content of the hydrogen tends to impact the refractory element content of the resultant coating. Generally, more refractory element is incorporated into the coating when the hydrogen is drier. In many modes of practice, dry hydrogen is used to obtain coatings with higher refractory element content.
  • coatings including 8 to 14 weight percent of Hf based on the total weight of the coating can be made from donor materials that include only 0.15 weight percent of Hf oxide based on the total weight of aluminum and alumina sources.
  • using a conventional approach without reducing gas and the incubation yields coatings with only 0.35 weight percent Hf from donor sources including 4.5 weight percent Hf oxide.
  • the present invention uses less Hf content in the sources and yet provides significantly more Hf in the coating by one to two orders of magnitude! The present invention significantly improves the efficiency of vapor phase deposition of hafnium and aluminum compared to what has been accomplished previously.
  • the temperature regime used for the incubation selectively favors oxide removal and formation of reactive Hf species relative to coating formation. Indeed, during experiments, it is believed that little if any aluminide coating formation occurs during the incubation phase at one or more temperatures in the range from 1700°F to 1840°F.
  • the time period of the incubation in the temperature range from 1700°F to 1850°F occurs for a time period sufficient to remove at least a portion of the residual oxide on the substrates and to prepare a vapor phase with an enhanced hafnium reactivity content.
  • the incubation occurs for a time period from 15 minutes to 5 hours, preferably 30 minutes to 5 hours, more preferably 45 minutes to 5 hours, most preferably 1 hour to.3 hours. In one experiment, holding the sample at 1775°F +/- 25°F for 90 minutes was suitable.
  • the process chamber is heated further to the desired coating temperature(s).
  • a suitable temperature is in the range from 1900°F to 2100°F.
  • the process chamber is held at such temperature(s) for sufficient time to produce a coating of the desired thickness.
  • a suitable holding period for this stage is a time period in the range from 3 hours to 10 hours.
  • the temperature was rapidly increased to 1975 °F and then maintained at this temperature until the desired coating thickness was established. Although the coating reaction proceeds at a suitable rate during this stage, it is believed that the reaction to produce additional reactive Hf species may still be occurring.
  • the weight percent of refractory element(s) incorporated into the coating (based on the total weight of the coating) is greater than the weight percent of the refractory element constituents included in the constituent donor materials (based on the total weight of the aluminum sources).
  • both heating and the flow of hydrogen gas is stopped and the process chamber is flushed with a flow of inert gas such as argon.
  • the process chamber is cooled under the inert flow to room temperature.
  • thermally grown oxide (TGO) layer 14 is provided on protective layer 13.
  • the protective coating 13 is sufficiently rich in Al to form a layer 14 that is a protective oxide (TGO) scale of CL-AI2O3.
  • the scale may be grown by any suitable oxidizing technique including growing the oxide thermally in an atmosphere including one or more oxidizing agents, chemically oxidizing the coating 13 via application of an oxidizing liquid, combinations of these, and the like.
  • the oxide layer 14 helps bond the ceramic topcoat 15 to the protective coating 13.
  • Layer 14 is formed by oxidizing layer 13 under conditions to form an oxide scale comprising aluminum oxide.
  • a thermally grown oxide forms between a bond coat and a ceramic coat when the surface of the bond coat oxidizes.
  • a portion of the thermally grown oxide may grow in situ as the ceramic layer is formed.
  • the thermally grown oxide layer forms in situ between the formed bond coat and ceramic coating when the component bearing the bond and ceramic coatings is used in a high temperature environment in which an oxidizing agent is present.
  • thermal barrier structure 12 is essentially fully formed before structure 12 is exposed to temperature cycling so that the displacement and stress effects caused by TGO growth between already existing bond coat and ceramic layers is avoided. Adhesion among the layers 13, 14, and 15 as well as between structure 12 and body 11 is substantially improved.
  • the thermally grown oxide layer 14 can be formed in a variety of ways. According to one mode of practice, the protective layer 13 is formed on body 11. Then, before the ceramic topcoat is formed, the coated body 11 is placed into a furnace and heated under conditions effective to oxidize the layer 13 to form oxide coating 14. Aluminum oxide forms. Other metals present in layer 13 might also form oxides. The aluminum oxide is formed to a point of oxide saturation after which little to no additional aluminum oxide forms. At this stage, the surface of layer 13 is generally fully oxidized with an oxide coating that forms an impermeable barrier protecting the remainder of layer 13 as well as body 11 against further oxidation.
  • the oxide layer 14 A variety of conditions may be used to form the oxide layer 14.
  • the oxide generally is formed in the presence of an oxidizing agent.
  • Oxygen in the ambient air is one suitable oxidizing agent.
  • Other oxidizing agents include ozone, peroxide, combinations of these, and the like.
  • An air furnace is an exemplary processing chamber useful for forming the oxide layer 14.
  • the temperature used to form the oxide may be selected from a wide range of temperatures. In some modes of practice, using a temperature in the range from about 900°F to about 1500°F, preferably 1200°F to about 1500 , more preferably 1300T to 1400°F would be suitable.
  • the processing time may occur over a wide range of time periods.
  • the processing time occurs for a time period sufficient to fully oxidize the surface of layer 13. More desirably, the processing time occurs for a time period sufficient to reach a point of oxide saturation such that further processing yields little if any additional oxide growth. In some modes of practice, a time period from 2 minutes to 8 hours ⁇ preferably 5 minutes to 4 hours, more preferably from about 30 minutes to 2 hours, even more preferably about one hour would be suitable.
  • Surface 29 of layer 14 is textured to enhance the adhesion of layer 14 to the ceramic layer 15.
  • the texture can be formed in a variety of ways. In some modes of practice, layer 14 is formed as a conformal coating over surface 27 so that the texture of surface 27 is telegraphed to some degree to surface 29. This allows direct texturizing of surface 29 after surface 29 is formed can be avoided. Such direct texturizing creates a risk of abrading through layer 14, losing protection in those through-abraded regions. In other modes of practice, surface 29 can be texturized after surface 29 is initially formed if desired.
  • Ceramic topcoat 15 helps to extend the service life of article 10 at least in part by reducing the surface temperature at the surface 17 of thermally grown oxide layer 14 relative to the surface 18 of the topcoat 15. In practice, it is believed that the temperature differential between surfaces 17 and 18 is above 100°C.
  • the ceramic topcoat 15 can be formed from a wide variety of ceramic materials. Suitable ceramic materials have one or more of low thermal conductivity, high oxygen permeability, and a relatively high coefficient of thermal expansion.
  • the topcoat 15 includes yttria-stabilized zirconia (YSZ) that contains about 2 to about 12 weight percent, preferably about 4 to about 8 weight percent yttrium oxide.
  • YSZ yttria-stabilized zirconia
  • the topcoat 15 can be formed in a variety of ways. In some embodiments, the topcoat may be applied either by plasma spraying or electron beam physical vapor deposition. Plasma spraying techniques, e.g., air plasma spraying, are preferred. In many embodiments, the topcoat has a thickness of about 100 microns to 400 microns. Because oxide layer 14 is substantially formed prior to formation of ceramic topcoat 15, ceramic topcoat can be formed in a wide variety of conditions, including under ambient conditions. In other modes of practice, ceramic topcoat 15 is formed in a protected environment comprising an inert gas and/or a reducing gas.
  • TBC thermal barrier coating
  • the coating system was an EBP VD type zirconia ceramic on a platinum aluminide bond coat applied to both X40 and Marm247 vane segments.
  • the aluminide coating was present on both the external and internal surfaces of the vane segment with platinum present only on the gas path of the part.
  • a vapor phase coating process to coat the internal and external surfaces of the 50 IK first stage vane was used to coat the vane segment with an aluminide coating.
  • the aluminide coated vane segments were then used in the experiments described below in Examples 2, 3, and 4.
  • a group of test parts was coated targeting about 2.5 to 3.0 mils of aluminide coating with a basic chemistry similar to current industry standards except in this case there was no precoat platinum additions via electroplating.
  • Aluminide coated vanes from Example 1 were used. The surfaces of the vanes were grit blasted to improve adherence of the plasma sprayed zirconia using 24 grit SiC at 15 PSI.
  • One purpose of the roughening is to provide a mechanical lock for the zirconia.
  • Grit blasting the aluminide coating is a standard procedure for preparation of the surface for the ceramic coating. Compared to a normal superalloy surface, the aluminide coating applied as a bondcoat is much more brittle and very thin. Therefore, special care was taken to roughen the aluminide surface sufficiently for the zirconia to adhere without completely removing the aluminide bond coat.
  • a vane segment was metallurgically sectioned through the airfoil using a diamond saw and then mounted to examine the coating
  • vane components were prepared differently than in Examples 1 and 2. Prior to aluminide coating, vane samples were grit blasted with 24 grit SiC at 15 PSI to produce a roughened surface. The aluminide coating was then applied to both the internal and external surfaces of the vanes as described in Example 2, except that the aluminide coatings were not grit blasted.
  • the visual appearances of the external surfaces of the aluminide coated vanes showed a rougher surface than the grit-blasted aluminide surfaces of Example 2, although the aluminide coatings of the present example were not as rough as the grit blasted vane surfaces prior to aluminide coating.
  • the aluminide coating followed the contours of the vane surface. This smoothed the high peaks, but the aluminide coating did not fill in the surfaces irregularities.
  • Example 2 Using the same process as Example 2, the same yttria stabilized zirconia was coated onto the aluminide coated vane samples. Visually, the ceramic coating adhered to more areas of the part than in Example 1. This was attributed to the fact that the vane samples could be grit blasted more aggressively since grit blasting was done before aluminide coating. This avoided the concern that the alumide coating would be blasted off if the grit blasting were practiced too aggressively after duminide coating. Optionally, the aluminide coatings could be lightly grit blasted or otherwise textured after aluminide coating if desired.
  • the coated vane segments were sectioned through the airfoils with a diamond saw.
  • the chipping on both the tension and compression sides was reduced relative to Example 2 but not eliminated.
  • Metallurgical examination of the coating system micro structure showed the bond coat to be uniform and adequate in thickness. Examination of the interface layer between the oxide layer and the ceramic top coat showed non uniform adherence, however.
  • an oxide layer forms on the bond coat during engine operation. If the oxide layer forms after the ceramic layer has been applied or during ceramic layer formation, the growth of the oxide layer introduces a strain which can impair the service life of the coating system. To avoid this, an oxide layer is deliberately thermally grown in the present example to the point of oxide saturation prior to applying the ceramic coating. That is, the oxide grows up to a certain point and then substantially stops growing even with further processing. This point of maximum oxide formation is the point of oxide saturation.
  • Example 3 because the aluminide surfaces of Example 3 were already roughened to improve the mechanical adherence, it was proposed to evaluate a coating system using a thermally grown oxide on the roughened, aluminide bond coat surface prior to applying a plasma sprayed yttria stabilized zirconia. This was done because the oxide layer would form subsequently anyway, and it was theorized that an oxide to oxide adhesion would be better than metal to oxide adhesion if the strain effects could be reduced or avoided.
  • test vanes were grit blasted and aluminide coated in accordance with Example 3. Following aluminide coating, the parts were heat treated in an air circulating furnace to deliberately create an oxide coating that would form during engine operation between the bond coat and the ceramic coat.
  • Temperatures of 1125°F, 1300°F, 1350°F and 1400°F were used to deliberately form the oxide layer on vane segments, respectively.
  • the color of the oxide formed depending on the temperature.
  • the oxide conditions allowed the oxide to grow to the point of oxide saturation.
  • the vane segments were plasma sprayed to form a ceramic coating on the thermally grown oxide in accordance with Examples 2 and 3. Visually, the ceramic coating was continuously formed and there was no evidence of adherence issues on the samples oxidized at the higher temperatures from 13 OOF to HOOF anywhere on the parts.
  • the vane segments were cut with a diamond saw exposing the coating to both compressive and tensile loads. No chipping was observed on any tension edges. Even when cut in tension, the coatings showed almost no chipping.
  • Example 4 Applying aluminide coating, growing thermal oxide, and then applying ceramic coatings to grit blasted vane segment
  • the process of Example 4 was repeated multiple times using vane samples in which the thermally grown oxide resulted from oxidation at both 1350 and 1400°F. Multiple sections were taken with the diamond saw to verify the eddy current thickness readings with actual thicknesses. Visual evaluation of the coating adherence was excellent and consistent across all samples. Metallurgical inspection of the coating adherence between the bond coat and ceramic top coat validated the excellent visual adherence.
  • Example 6 Further confirmation of the adherence of the thermal barrier coating system is provided by the fact that the removal of the zirconia layer was performed to reuse samples which were not destructively evaluated. This was done by grit blasting the coated vanes using aluminum oxide at a variety of pressures. As the process was modified from Example 2 through Example 4, it became more difficult and time consuming to prepare parts for future trials.
  • Example 6 Further confirmation of the adherence of the thermal barrier coating system is provided by the fact that the removal of the zirconia layer was performed to reuse samples which were not destructively evaluated. This was done by grit blasting the coated vanes using aluminum oxide at a variety of pressures. As the process was modified from Example 2 through Example 4, it became more difficult and time consuming to prepare parts for future trials. Example 6
  • the substrates included Co -based and Ni-based superalloys.
  • the aluminum source included 5 lbs of aluminum powder mixed with 95 lbs of alumina powder; This was mixed with 10 weight percent of A1F 3 based on the total weight of the aluminum source.
  • the mixture was placed into a process chamber in trays. Depending upon the run, 0.1 to 0.50 weight percent of Hf0 2 powder was sprinkled on top of the mixture. The percentage of the hafnium oxide was based on the total weight of the aluminum source and the AIF3.
  • the substrate was placed into the process chamber and supported on a pre-conditioned mesh above the donor materials.
  • the process chamber was purged with argon. Maintaining the flow of argon, the temperature in the process chamber was increased to 1450°F. At this point, a flow of hydrogen was established and maintained while the flow of argon stopped. The temperature was then further increased to 1750°F. At this stage, the temperature ramp rate was substantially reduced so that the sample incubated at 1775°F +/- 25°F for 90 minutes. In accordance with principles of the present invention, it is believed that a substantial portion of the hafhia was reduced to one or more reduced species during this time period in this temperature range.
  • the process chamber was maintained at 1975T or 2000°F under a flow of hydrogen for about 6 hours (Ni-based alloy substrates) or about 15 hours (Co-based alloy substrates to complete the formation of the coating on the substrate.
  • heating and the flow of hydrogen was stopped, and a flow of argon was established to purge the chamber.
  • the chamber contents were cooled to room temperature under the flow of argon. This temperature is suitable when the substrate includes a nickel-based superalloy. For a substrate including a Co-based superalloy, coating temperatures approximately 25°F higher would be more suitable.
  • hafnium to exist as discrete particles of hafnium containing compound(s).
  • the benefits of hafnium additions of this type to improve the oxidation resistance are well established.
  • weight percent AIF3 is based on the total weight of the aluminum source.
  • the weight percent of the Hf0 2 based on the total weight of the aluminum source and A1F 3 .
  • hafnium contents in the range from 5 to 39.9 weight percent were achieved using donor materials that included no more than 0.50 weight percent of hafnium oxide.
  • conventional vapor phase coating strategies selectively favor aluminum over Hf deposition even when using higher amounts of Hf donor materials are used, the present invention in practical effect reverses this co- deposition selectivity to transfer the Hf consistently and efficiently when co- deposited with aluminum.
  • Oxidation resistance at high temperature also was assessed qualitatively. It is known that Hf facilitates oxidation resistance up to a certain level of

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Abstract

La présente invention concerne des stratégies de fabrication de revêtements d'aluminure et de systèmes de revêtement barrière thermique correspondants qui protègent des substrats métalliques dans des environnements à haute température. Selon un aspect de la présente invention, le dépôt de revêtement d'aluminure comprend au moins deux étapes de chauffage qui ont lieu en présence d'un gaz réducteur. Une première étape de chauffage a lieu en présence d'un gaz réducteur dans des conditions qui augmentent ou alors favorisent significativement la réduction des composés réfractaires non halogénés par rapport à la formation du revêtement. Il en résulte que des niveaux étonnamment élevés de teneur en élément réfractaire peuvent ensuite être incorporés dans les revêtements résultants lors de la seconde étape de chauffage même lorsque les matériaux donneurs contiennent une teneur en élément réfractaire relativement faible. Le procédé fournit des revêtements uniformes et est cohérent d'un lot à l'autre.
PCT/US2014/045761 2013-07-09 2014-07-08 Procédés de fabrication de revêtements d'aluminure par co-dépôt d'aluminium et d'un ou plusieurs éléments réfractaires et leur utilisation dans des systèmes de barrière thermique pour protéger des substrats contenant du métal dans des environnements à haute température WO2015006330A1 (fr)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016130548A1 (fr) * 2015-02-10 2016-08-18 Arcanum Alloy Design, Inc. Procédés et systèmes de revêtement à base de boues
US11261516B2 (en) 2016-05-20 2022-03-01 Public Joint Stock Company “Severstal” Methods and systems for coating a steel substrate
CN115961235A (zh) * 2022-12-28 2023-04-14 江苏迈信林航空科技股份有限公司 一种航空核心组件加工工艺及其装置

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US5658614A (en) * 1994-10-28 1997-08-19 Howmet Research Corporation Platinum aluminide CVD coating method
US20020184971A1 (en) * 2000-03-21 2002-12-12 Myrick James J. Production of metals and their alloys
US20030211242A1 (en) * 2002-05-07 2003-11-13 Shah Atul Natverlal Dimensionally controlled pack aluminiding of internal surfaces of a hollow article
US20120213928A1 (en) * 2009-05-18 2012-08-23 Wang Yongqing Forming reactive element modified aluminide coatings with low reactive element content using vapor phase techniques

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US5658614A (en) * 1994-10-28 1997-08-19 Howmet Research Corporation Platinum aluminide CVD coating method
US20020184971A1 (en) * 2000-03-21 2002-12-12 Myrick James J. Production of metals and their alloys
US20030211242A1 (en) * 2002-05-07 2003-11-13 Shah Atul Natverlal Dimensionally controlled pack aluminiding of internal surfaces of a hollow article
US20120213928A1 (en) * 2009-05-18 2012-08-23 Wang Yongqing Forming reactive element modified aluminide coatings with low reactive element content using vapor phase techniques

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016130548A1 (fr) * 2015-02-10 2016-08-18 Arcanum Alloy Design, Inc. Procédés et systèmes de revêtement à base de boues
US10876198B2 (en) 2015-02-10 2020-12-29 Arcanum Alloys, Inc. Methods and systems for slurry coating
US11261516B2 (en) 2016-05-20 2022-03-01 Public Joint Stock Company “Severstal” Methods and systems for coating a steel substrate
CN115961235A (zh) * 2022-12-28 2023-04-14 江苏迈信林航空科技股份有限公司 一种航空核心组件加工工艺及其装置

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