Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
  • C23C16/56—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
  • C23C10/00—Solid state diffusion of only metal elements or silicon into metallic material surfaces
  • C23C10/02—Pretreatment of the material to be coated
• • 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
  • C23C10/04—Diffusion into selected surface areas, e.g. using masks
• • 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
  • C23C10/28—Solid state diffusion of only metal elements or silicon into metallic material surfaces using solids, e.g. powders, pastes
  • C23C10/30—Solid state diffusion of only metal elements or silicon into metallic material surfaces using solids, e.g. powders, pastes using a layer of powder or paste on the surface
• • 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
  • C23C10/28—Solid state diffusion of only metal elements or silicon into metallic material surfaces using solids, e.g. powders, pastes
  • C23C10/30—Solid state diffusion of only metal elements or silicon into metallic material surfaces using solids, e.g. powders, pastes using a layer of powder or paste on the surface
  • C23C10/32—Chromising
• • 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
  • C23C10/28—Solid state diffusion of only metal elements or silicon into metallic material surfaces using solids, e.g. powders, pastes
  • C23C10/34—Embedding in a powder mixture, i.e. pack cementation
  • C23C10/36—Embedding in a powder mixture, i.e. pack cementation only one element being diffused
  • C23C10/48—Aluminising
• • 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
• • 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
• • 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
  • F01D5/30—Fixing blades to rotors; Blade roots ; Blade spacers
  • F01D5/3092—Protective layers between blade root and rotor disc surfaces, e.g. anti-friction layers
• • 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
  • F05D2300/12—Light metals
  • F05D2300/121—Aluminium
• • 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
  • F05D2300/20—Oxide or non-oxide ceramics
  • F05D2300/21—Oxide ceramics
  • F05D2300/2112—Aluminium oxides

Definitions

• the present invention is directed to coating processes for applying a bifurcated coating to an article. More particularly, the present invention is directed to applying a bifurcated coating to an article including an aluminide coating and a chromide coating.
• Gas turbines include components, such as buckets (blades), nozzles (vanes), combustors, shrouds, and other hot gas path components which are coated to protect the components from the extreme temperatures, chemical environments and physical conditions found within the gas turbines. Different coating systems may be applied to different locations of the same turbine components to meet the local conditions which vary across the turbine components.
• the airfoil and shank of a turbine bucket experience different conditions, and whereas the airfoil may be subjected to conditions which lead to oxidation, the shank may be more susceptible to conditions which lead to pitting.
• Providing coatings to address oxidative conditions and pitting conditions typically requires multiple coating processes which lead to long coating cycles, multi-step masking procedures, and sequential furnace runs, particularly in instances where the separate coating systems are incompatible with one another.
• a coating process for applying a bifurcated coating to an article includes applying an aluminizing slurry to a first portion of the article, applying a chromizing slurry to a second portion of the article, and simultaneously heat treating the article, the aluminizing slurry, and the chromizing slurry.
• Heat treating the aluminizing slurry forms an aluminide coating on the first portion of the article and an aluminide diffusion zone between the article and the aluminide coating.
• Heat treating the chromizing slurry forms a chromide coating on the second portion of the article and a chromide diffusion zone between the article and the chromide coating.
• the first portion and the second portion are both maintained in an unmasked state while applying the aluminizing slurry and the chromizing slurry and during the heat treating.
• FIG. 1 is a schematic view of an article undergoing a coating process, according to an embodiment of the present disclosure.
• FIG. 2 is a schematic view of a coated article, according to an embodiment of the present disclosure.
• FIG. 3 is a perspective view of a coated turbine component, according to an embodiment of the present disclosure.
• a coating process includes applying an aluminizing slurry 102 to a first portion 104 of an article 100, applying a chromizing slurry 106 to a second portion 108 of the article 100, and simultaneously heat treating the article 100, the aluminizing slurry 102, and the chromizing slurry 106.
• the coating process includes masking a third portion 110 of the article prior to the application of the aluminizing slurry 102 and the chromizing slurry 106. Any suitable masking process may be employed to prevent the third portion 110 from being coated by the aluminizing slurry 102 and the chromizing slurry 106.
• the coating process may include a pre-coating cleaning prior to applying either of the aluminizing slurry 102 and the chromizing slurry 106.
• the cleaning may include any suitable cleaning process, including, but not limited to, steam cleaning, ultrasonic cleaning, solvent treatment, grit blasting, and combinations thereof.
• the first portion 104 may be a contiguous area (as shown in FIG. 3) or may include a plurality of isolated regions (as shown in FIGS. 1 and 2)
• the second portion 108 may be a contiguous area (as shown in FIG. 3) or may include a plurality of isolated regions(as shown in FIGS. 1 and 2)
• the third portion 110 may be a contiguous area (as shown in FIG. 3) or may include a plurality of isolated regions (as shown in FIGS. 1 and 2).
• the aluminizing slurry 102 and the chromizing slurry 106 may be applied directly to any suitable surface, including, but not limited to, a metallic surface.
• the aluminizing slurry 102 and the chromizing slurry 106 are applied directly to a substrate of the article 100.
• the substrate may be any suitable material, including, but not limited to an iron-based superalloy, a nickel-based superalloy, a cobalt-based superalloy, or a combination thereof.
• the article 100 includes a bond coat, and the aluminizing slurry 102 and the chromizing slurry 106 are applied directly to the bond coat.
• the bond coat may be any suitable material, including, but not limited to a MCrAl Y, an aluminide diffusion coating, or a combination thereof.
• the aluminizing slurry 102 includes a donor powder, an activator powder, and a binder, the donor powder including a metallic aluminum alloy having a melting temperature higher than aluminum, and the binder including at least one organic polymer gel.
• the aluminizing slurry 102 may include any suitable composition, including, but not limited to, a composition having, by weight, about 35 to about 65% of the donor powder, about 1 to about 25% of the activator powder, and about 25 to about 60% of the binder.
• the donor powder of the aluminizing slurry 102 may include a metallic aluminum alloy having a melting temperature higher than aluminum (melting point of about 1,221 °F).
• the donor powder includes metallic aluminum alloyed with chromium, iron, another aluminum alloying agent, or a combination thereof, provided that the alloying agent does not deposit during the diffusion aluminiding process, but instead serves as an inert carrier for the aluminum of the donor material.
• the donor powder includes a chromium-aluminum alloy such as, but not limited to, by weight, 44% aluminum, balance chromium and incidental impurities.
• the donor powder has a particle size of up to 100 mesh (149 ⁇ ), alternatively up to -200 mesh (74 ⁇ ). Without being bound by theory, it is believed that the donor powder being a fine powder reduces the likelihood that the donor powder will be lodged or entrapped within the article 100.
• the activator powder of the aluminizing slurry 102 may include any suitable material, including, but not limited to, ammonium chloride, ammonium fluoride, ammonium bromide, another halide activator or combinations thereof. Suitable materials for the activator powder react with aluminum in the donor material to form a volatile aluminum halide, such as, but not limited to, AlCh or A1F 3 , which reacts at the article 100 to deposit aluminum, which diffuses into the article 100.
• a volatile aluminum halide such as, but not limited to, AlCh or A1F 3
• the binder of the aluminizing slurry 102 may include at least one organic polymer gel.
• Suitable binders include, but are not limited to, a polymeric gel available under the name Vitta Braz-Binder Gel from the Vitta Corporation, and low molecular weight polyols such as polyvinyl alcohol.
• the binder further includes a cure catalyst, an accelerant, or both, such as, but not limited to, sodium hypophosphite.
• the aluminizing slurry 102 is free of inert fillers and inorganic binders.
• the absence of inert fillers and inorganic binders prevents such materials from sintering and becoming entrapped in the article 100.
• the chromizing slurry 106 includes a donor powder, an inorganic salt having a melting point that is less than or equal to about 800 °C, an activator, and a binder, wherein the donor powder includes chromium.
• the donor powder may include chromium in the form for chromium powder, and may further include an aluminum powder.
• the chromium powder includes an additive such as aluminum, cobalt, nickel, silicon, or mixtures thereof. In another embodiment, if aluminum powder is present, the aluminum powder includes an additive such as cobalt, nickel, silicon, or mixtures thereof.
• the chromizing slurry 106 includes donor powder particles having any suitable size, including, but not limited to, particles having a mean diameter of about 1 to about 10 microns (i.e., micrometers ( ⁇ )) as measured using a conventional particle size analyzer.
• the purity of the donor powder particles may be at least about 95% by weight, and in one embodiment is at least about 99% by weight.
• the inorganic salt of the chromizing slurry 106 may be any suitable inorganic salt having a melting point that is less than or equal to about 800 °C, including, but not limited to, KC1, LiF, LiCl, CaCh, MgCh, KOH, or combinations thereof.
• the inorganic salt is a binary mixture of two inorganic salts.
• the salts in the binary mixture are in a well-mixed solid powder form.
• Such binary mixtures of two inorganic salts may include, but are not limited to, KCl-BaCh, NaCl-KCl, NaCl-CaCh, NaCl-BaCh, NaCl- MgCh, MgCh-BaCh, MgCh CaCh, NaCl-Na 2 C0 3 , and mixtures thereof.
• the binary mixtures may have various molar ratios of the component salts.
• the salt is KC1- BaCl 2 in a 0.555:0.445 molar ratio.
• the salt is NaCl-BaCl 2 in a 0.6:0.4 molar ratio.
• the molar ratio of the salts in a binary mixture affects the melting point of the binary mixture. Accordingly, the molar ratio of the binary mixture may be controlled to select a melting point of the binary mixture that is less than or equal to about 800 °C.
• the inorganic salt is a ternary mixture of three inorganic salts. Typically, the salts in the ternary mixture are in a well-mixed solid powder form.
• Such ternary mixtures of two inorganic salts may include, but are not limited to, LiF-NaF-MgF 2 , LiCl-KCl-CaCl 2 , LiF-PuF 3 - ThF4, and mixtures thereof.
• the ternary mixtures may have various molar ratios of the component salts. As with the binary mixtures, the molar ratio of the salts in a ternary mixture affects the melting point of the ternary mixture. Accordingly, the melting point of the ternary mixture may be adjusted by altering the molar ration of the three salts so that the melting point is less than or equal to about 800 °C.
• the activator of the chromizing slurry 106 may be any suitable activator, including, but not limited to, ammonium halides, chromium halides, aluminum halides, and mixtures thereof.
• the activator is H4CI, FUF, FUBr, CrCl 2 , CrCh, AlCh, or a combination thereof.
• the binder of the chromizing slurry 106 may be any suitable binder which promotes cohesiveness of the chromizing slurry 106 and which decomposes when exposed to a predetermined temperature.
• the predetermined temperature is a temperature within the range from about 600 °C to about 1300 °C, alternatively the temperature range from about 800 °C to about 950 °C.
• the binder may imbue the chromizing slurry 106 with the physical properties of a paste or a viscous liquid at room temperature.
• the binder may include one component or a combination of components.
• the binder is a waterborne acrylic resin based binder, at least one organofunctional silane based binder, at least one cellulose-derived water-soluble polymer based binder, at least one polyvinyl alcohol based binder, at least one epoxy resin based binder, at least one alcohol soluble resin based binder, or a combination thereof.
• the binder is "BINDER B-200", which is commercially available from APV Engineered Coatings.
• BINDER B-200 refers to a composition including, by weight, about 69% water, about 20% to about 30% ethanol, about 1% to about 5% polyvinyl alcohol, about 1% to about 5% isopropanol, and about 0.1%) to about 1%) 4-methyl-2-pentanone.
• the chromizing slurry 106 includes, by weight, about 1%> to about 60%) of the donor powder, about 1%> to about 70% of the inorganic salt, about 1%> to about 30%> of the activator, and at least about 1%> of the binder.
• the chromizing slurry 106 includes: a chromium powder; a binary mixture of two inorganic salts selected from the group consisting of KCl-BaCk, NaCl- KC1, NaCl-CaCh, NaCl-BaCk, NaCl-MgCk, MgCk-BaCk, MgCk CaCk, NaCl-Na 2 C03, and mixtures thereof, wherein the binary mixture has a melting point that is less than or equal to about 800 °C; an activator selected from the group consisting of NH 4 C1, NH4F, NH 4 Br, CrCk, CrCk, AlCh, and mixtures thereof; and a binder.
• a binary mixture of two inorganic salts selected from the group consisting of KCl-BaCk, NaCl- KC1, NaCl-CaCh, NaCl-BaCk, NaCl-MgCk, MgCk-BaCk
• the binary mixture of two inorganic salts is KCl-BaCk and the activator is NH4CI.
• the binary mixture of two inorganic salts is NaCl-BaCk and the activator is
• the aluminizing slurry 102 and the chromizing slurry 106 may be applied, independently, by any suitable application technique, including, but not limited to, high- velocity oxygen fuel deposition, vacuum plasma spray deposition, painting, and combinations thereof.
• heat treating the aluminizing slurry 102 forms an aluminide coating 200 (as shown in FIG. 2) on the first portion 104 of the article 100 and an aluminide diffusion zone 202 between the article 100 and the aluminide coating 200.
• Heat treating the chromizing slurry forms a chromide coating 204 (as shown in FIG. 2) on the second portion 108 of the article 100 and a chromide diffusion zone 206 between the article 100 and the chromide coating 204.
• the first portion 104 and the second portion 108 are both maintained in an unmasked state while applying the aluminizing slurry 102 and the chromizing slurry 106 and during the heat treating.
• the aluminide coating 200 and the chromide coating 204 define a bifurcated coating 208. Forming the aluminide coating 200 may include forming the aluminide coating 200 as an outward-type coating.
• the heat treating of the article 100, the aluminizing slurry 102, and the chromizing slurry 106 may include any suitable temperature, including, but not limited to a temperature within a range of about 1,750 °F to about 2, 100 °F, alternatively between about 1,800 °F to about 2,075°F, alternatively between about 1,850 °F to about 2,050 °F.
• the heat treating of the article 100, the aluminizing slurry 102, and the chromizing slurry 106 includes heating the article 100, the aluminizing slurry 102, and the chromizing slurry 106 to a temperature which is at or above the solution temperature for the aluminizing slurry 102 and the chromizing slurry 106.
• the heat treatment may include any suitable duration, including, but not limited to a duration from about 2 hours to about 8 hours, alternatively between about 3 hours to about 7 hours, alternatively between about 4 hours to about 6 hours, alternatively between about 4.5 hours to about 5.5 hours, alternatively about 5 hours.
• heat treating the article 100, the aluminizing slurry 102, and the chromizing slurry 106 consists of a single furnace cycle.
• applying the bifurcated coating 208 to the article 100 further includes aging the aluminide coating 200, the aluminide diffusion zone 202, the chromide coating 204, and the chromide diffusion zone 206.
• aging is distinct from a "furnace cycle” in that the aging process is carried out at a lower temperature than the furnace cycle, and may be conducted in a separate heating environment from the furnace of the furnace cycle.
• the article 100 following application of the aluminizing slurry 102 and the chromizing slurry 106 to the article 100, the article 100 is placed immediately in a coating chamber to perform the diffusion process.
• the coating chamber is evacuated, and may be backfilled with an inert or vacuum (with partial pressure) atmosphere (such as argon or hydrogen, respectively).
• the temperature within the coating chamber is raised to a temperature sufficient to burn off the binder (e.g.
• the bifurcated coating 208 having the aluminide coating 200, the aluminide diffusion zone 202, the chromide coating 204, and the chromide diffusion zone 206.
• Heating the aluminizing slurry 102 and the chromizing slurry 106 may form a residue on the bifurcated coating 208.
• the bifurcated coating 208 may be subjected to a post-coating cleaning following the heat treating.
• the post-coating cleaning may include any suitable technique, including, but not limited to, directed forced gas flow, grit blasting, glass bean blasting, solvent treatment, ultrasonic treatment, and combinations thereof.
• the article 100 may be any suitable article, including, but not limited to a turbine component 300.
• Suitable turbine components include, but are not limited to, a hot gas path component, a bucket (blade) 302, a nozzle (vane), a shroud, a combustor, a combustion component, or a combination thereof.
• the turbine component 300 is a bucket (blade) 302
• the first portion 104 is an airfoil 304
• the second portion 108 is a shank 306, and the third portion 110 is a root 308.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Materials Engineering (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• General Engineering & Computer Science (AREA)
• General Chemical & Material Sciences (AREA)
• Turbine Rotor Nozzle Sealing (AREA)

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• 2016
  • 2016-06-22 US US15/189,854 patent/US10053779B2/en active Active
• 2017
  • 2017-05-02 EP EP17735679.7A patent/EP3475459B1/en active Active
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