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
  • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
  • C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
  • C23C14/08—Oxides
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
  • C04B35/48—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on zirconium or hafnium oxides, zirconates, zircon or hafnates
  • C04B35/486—Fine ceramics
  • C04B35/488—Composites
• • 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
  • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
  • C23C14/02—Pretreatment of the material to be coated
  • C23C14/024—Deposition of sublayers, e.g. to promote adhesion of the coating
  • C23C14/025—Metallic sublayers
• • 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
  • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
  • C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
  • C23C14/08—Oxides
  • C23C14/083—Oxides of refractory metals or yttrium
• • 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
  • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
  • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
  • C23C14/24—Vacuum evaporation
  • C23C14/28—Vacuum evaporation by wave energy or particle radiation
  • C23C14/30—Vacuum evaporation by wave energy or particle radiation by electron bombardment
• • 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
  • C23C28/32—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
  • C23C28/3215—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 at least one MCrAlX 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
  • C23C28/32—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one pure metallic layer
  • C23C28/325—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one pure metallic layer with layers graded in composition or in physical properties
• • 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
• • 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
  • F01D5/284—Selection of ceramic materials
• • 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
  • 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
  • F05D2300/20—Oxide or non-oxide ceramics
  • F05D2300/21—Oxide ceramics
  • F05D2300/2118—Zirconium oxides
• • 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
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/12—All metal or with adjacent metals
  • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
  • Y10T428/12535—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.] with additional, spatially distinct nonmetal component
  • Y10T428/12611—Oxide-containing component
• • 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
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/12—All metal or with adjacent metals
  • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
  • Y10T428/12535—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.] with additional, spatially distinct nonmetal component
  • Y10T428/12611—Oxide-containing component
  • Y10T428/12618—Plural oxides
• • 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
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/12—All metal or with adjacent metals
  • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
  • Y10T428/12771—Transition metal-base component
  • Y10T428/12861—Group VIII or IB metal-base component
  • Y10T428/12937—Co- or Ni-base component next to Fe-base component

Definitions

• the present invention relates generally to the field of thermal barrier coatings that are used in elevated temperature applications such as gas turbine engines.
• this invention relates to a thermal insulating ceramic coating, which has a low thermal conductivity as well as a long service life, and to the metallic articles such as turbine components, (e.g. blades and vanes) that the coatings are applied to prevent the components from overheating during high temperature operation.
• thermal barrier coatings having low thermal conductivity to insulate effectively the thermal transfer to the components used in gas turbine engines, as well as providing a coated component having a long service life.
• Efforts have been made to lower the thermal conductivity of thermal barrier coatings by modifying the chemistry and microstructure of current 7YSZ thermal barrier coating systems as disclosed in EP0816526A2, US Patent 6071628, US Patent 5846605, US Patent 6183884B1, US Patent 5792521, US Patent 5687679, W01/63008 and US Patent 6284323B1.
• thermal barrier coatings decreased thermal conductivity of thermal barrier coatings to various extents with the minimum reported to be about half the thermal conductivity of typical 7 wt% yttria stabilized zirconia (7YSZ). It is a main object of this invention to decrease thermal conductivity of thermal barrier coatings by providing a new ceramic material with low thermal conductivity. This invention also provides a method of applying such a thermal barrier coating system onto the metallic parts providing increased thermal insulation capability and prolonged durability.
• Fig. 1 shows the ceramic coating, Re x Zr 1-x O y with Z dissolved in, which was applied by EBPVD onto a metallic bond coat
• Fig. 2 shows the ceramic coating, Re x Zr 1-x O y with Z dissolved in, applied in a layered microstructure.
• Figures 3(a) and 3(b) shows a protective ceramic top coat on the ceramic coating, Re x Zr 1-x O y with Z dissolved in.
• Figure 4 shows the specific heat of coatings vs. temperature.
• Figure 5 shows the thermal diffusivity of coatings vs. temperature.
• Figure 6 shows the thermal conductivity of coatings as deposited vs. temperature.
• Figure 7 shows the thermal conductivity of coatings as aged vs. temperature.
• this invention provides a thermal barrier ceramic coating for application to a metallic article, with the ceramic coating having a formula of Re x Zr 1-x O y with Z dissolved in, wherein Re is a rare earth element selected from the group consisting of Ce, Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb and Lu, where O ⁇ x ⁇ 0.5 and 1.75 ⁇ y ⁇ 2 and Z is an oxide of a metal selected from the group consisting of Y, Mg, Ca, Hf and mixtures thereof.
• Re is Nd and Z is yttrium.
• This invention provides a thermal barrier ceramic coating having a formula of Re x Zr 1-x O y with Z dissolved in, where 0 ⁇ x ⁇ 0.5, 1.75 ⁇ y ⁇ 2, Re is a rare earth element selected from Ce, Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb and Lu and Z is an oxide of a metal selected from the group consisting of Y, Mg, Ca, Hf and mixtures thereof.
• the ceramic is formed by doping oxides of the selected rare earth elements and the selected metal oxides into a host zirconia ceramic.
• a preferred embodiment is where Re is Nd with the formula Nd x Zr 1-x O y , where 0 ⁇ x ⁇ 0.5 and 1.75 ⁇ y ⁇ 2 and Z is yttria.
• the Nd x Zr ⁇ x O y ceramic coating with yttria dissolved in can be prepared by doping 4 to 15 mole % of Nd 2 0 3 and 2 to 14 mole %, preferably 2.6 to 5.6 mole %, Y 2 0 3 into Zr0 2 .
• Nd x Zr 1-x O y is Ndo .1 Zro .
• the ceramic coating of this invention is applied to a metallic article providing a thermal barrier coating with low thermal conductivity and high resistance to cyclic oxidation.
• the ceramic coating of this invention has a low thermal conductivity generally within the range of about 0.78 to 1.02 W/mK from 600°C to 1100°C. This thermal conductivity is around 50% of the measured thermal conductivity of a typical 7YSZ coating (1.65-2.22 W/mK from 600°C to 1100°C).
• the ceramic coating of this invention has a high resistance to cyclic oxidation.
• the ceramic coating can be deposited as a straight columnar microstructure or a saw tooth microstructure or a layered microstructure or mix of thereof for further reduction in thermal conductivity. Generally, the ceramic coating is applied to a thickness within the range of about 5 to 500 ⁇ m, preferably about 25 to 400 ⁇ m. In a layered microstructure, the ceramic coating can have at least 2 layers, preferably from 5 to 100 layers, each at least about 1 ⁇ m thick, preferably about 5 to 25 ⁇ m thick. The process of applying the ceramic coating by EBPVD is similar to that of applying 7YSZ in production.
• the evaporating source in a crucible is a solid ingot of the Re x Zr 1-x O y with Z dissolved in, which is sintered zirconia doped with the selected rare earth oxide and selected metal oxide.
• the layered microstructure of the ceramic coating, Re x Zr 1-x O y with Z dissolved in, is applied by evaporating the solid ingots from two crucibles under controlled gun on off program of electron beam physical vapor deposition.
• the ceramic coating, Re x Zr ⁇ -x O y with yttria dissolved in, with 6-8wt% YSZ at the top is deposited by evaporating the solid ingot of Re x Zr 1-x O y with Z dissolved in from one crucible and 6-8wt% YSZ ingot from another crucible by electron beam physical vapor deposition.
• a metallic bond coat is applied onto the metallic article, such as a nickel or cobalt based superalloys prior to deposition of the ceramic coating.
• the metallic bond coat can be a MCrAlY alloy, wherein M is Ni, Co or mixtures thereof.
• Such alloys have a broad composition of 10 to 35% chromium, 5 to 15% aluminum, 0.01 to 1% yttrium, or hafnium, or lanthanum, with M being the balance. Minor amounts of other elements such as Ta or Si may also be present.
• the MCrAlY bond coat can be applied by EBPVD, though sputtering, low pressure plasma or high velocity oxy fuel spraying or entrapment plating may also be used.
• the metallic bond coat can be comprised of an intermetallic aluminide such as nickel aluminide or platinum aluminide.
• the aluminide bond coating can be applied by standard commercially available aluminide processes whereby aluminum is reacted at the substrate surface to form an aluminum intermetallic compound, which provides a reservoir for the growth of an alumina scale oxidation resistant layer.
• the aluminide coating is predominately composed of aluminum intermetallic [e.g., NiAl, CoAl and (Ni, Co) Al phase] formed by reacting aluminum vapor species, aluminum rich alloy powder or surface layer with the substrate elements in the outer layer of the superalloy component. This layer is typically well bonded to the substrate.
• Aluminizing may be accomplished by one of several conventional prior art techniques, such as, the pack cementation process, spraying, chemical vapor deposition, electrophoresis, sputtering, and appropriate diffusion heat treatments.
• Other beneficial elements can also be incorporated into diffusion aluminide coatings by a variety of processes.
• Beneficial elements include Pt, Pd, Si, Hf, Y and oxide particles, such as alumina, yttria, haf ia, for enhancement of alumina scale adhesion, Cr and Mn for hot corrosion resistance, Rh, Ta and Cb for diffusional stability and/or oxidation resistance and Ni, Co for increasing ductility or incipient melting limits.
• the coating phases adjacent to the alumina scale will be platinum aluminide and/or nickel-platinum aluminide phases (on a Ni-base superalloy).
• an alumina (i.e., aluminum oxide) layer is formed over the metallic bond coat.
• This alumina layer provides both oxidation resistance and a bonding surface for a ceramic coating.
• the alumina layer may be formed before the ceramic coating is applied, during application of the coating or subsequently by heating the coated article in an oxygen containing atmosphere at a temperature consistent with the temperature capability of the superalloy, or by exposure to the turbine environment.
• the sub-micron thick alumina scale will thicken on the aluminide surface by heating the material to normal turbine exposure conditions.
• the thickness of the alumina scale is preferably sub-micron (up to about one micron).
• the alumina layer may also be deposited by chemical vapor deposition following deposition of the metallic bond coat. Alternatively, the metallic bond coat may be eliminated if the substrate is capable of forming a highly adherent alumina scale or layer. Examples of such substrates are very low sulfur ( ⁇ 1 ppm) single crystal superalloys, such as PWA 1487 and Rene N5, which also contain 0.1 % yttrium to enhance adhesion of the thermally grown alumina scale. Fig.
• FIG. 1 shows the ceramic coating, Re x Zr 1-x O y with Z dissolved in, 40 which was applied by EBPVD onto a metallic bond coat 20, such as a MCrAlY and/or platinum modified aluminide.
• the bond coat 20 was applied to the metallic article 10, of nickel or cobalt based superalloys prior to the application of the ceramic coating 40.
• the bond coat 20 provides strong adhesion between the metallic substrate 10 and the ceramic coating 40.
• the ceramic coating adheres to the bond coat 20 through a thermally grown alumina film 30 on the bond coat 20.
• Figure 2 shows the ceramic coating, Re x Zr 1-x O y with Z dissolved in, 40 applied in a layered microstructure.
• FIGS 3(a) and 3(b) show a protective ceramic top coat 50 which is coated after the columnar ceramic coating Re x Zr 1-x O y with Z dissolved in 40, to provide increased erosion resistance on the top surface which is subject to hot gas impact during turbine engine operation.
• This protective ceramic top coat can be a dense and/or wide column of ceramic coating Re x Zr 1-x O y with Z dissolved in, or alternatively, layer 50 could also be 6-8wt%> YSZ.
• This protective ceramic top coat, 50 for erosion resistance generally has a thickness of about 5 to 50 ⁇ m preferably about 10 to 25 ⁇ m thick.
• a protective top coat of 7YSZ with an appropriate thickness for erosion resistance on the ceramic coating, Ndo . iZro .9 O 1 . 95 with 2.6 mole % Y 2 0 3 dissolved in, provides a thermal conductivity which is equivalent to the ceramic coating without the protective ceramic top coat.
• the ceramic coating system of this invention provides many advantages for use in gas turbine engines. The reduction in thermal conductivity of 50 percent can reduce the thickness required for the thermal barrier coating (TBC) by approximately one half for the same degree of thermal insulation. This will lower the cost of the TBC due to the time saved in applying the coating, ingot material savings and energy savings in production. Decreasing in the coating thickness will also lower the weight of the gas turbine component, e.g.
• iZro .9 Oi .95 with yttria dissolved in was tested using Differential Scanning Calorimetry (DSC) on an Omnitherm DSC 1500 in Oak Ridge National Lab.
• the samples are free standing ceramic coating, i.e. an intact ceramic coating without substrate.
• the free standing samples of ceramic coating are 180 to 230 ⁇ m thick and are machined to 6mm in diameter to meet the requirements of the testing instrument.
• the test was run in the temperature range of 100°C to 1100°C using sapphire as the baseline standard.
• the results in Fig. 4 show that the specific heat of Ndo . iZro .9 Oi .95 ceramic coating with yttria dissolved in is about 5%-7%> lower than that of typical 7YSZ.
• the thermal diffusivity ( ⁇ ) was measured by the laser flash technique at Oak Ridge National Laboratory on a Flashline 5000 Thermal Diffusivity System, see H. Wang, R.B. Dinwiddie and P. S. GAAL, "Multiple Station Thermal Diffusivity Instrument", THERMAL CONDUCTIOVITY 23, Proceedings of the Twenty- Third International Thermal Conductivity Conference, PI 19-126. Two or three free standing ceramic samples of each kind were measured at every 100-degree interval from 600°C to 1100°C. Three measurements of each sample were conducted at every temperature. The time-temperature curves were analyzed by the method of Clark and Taylor, which takes into account radiation losses and uses the heating part of the curve to calculate thermal diffusivity.
• the average readings of two or three samples with three measurements in each at temperature from 600°C to 1000°C are plotted in Fig. 5. It shows the thermal diffusivity of Ndo.iZro .9 Oi. 95 ceramic coating with yttria dissolved in is around 40% lower than that of typical 7YSZ coating. A layered microstructure further decreases the thermal diffusivity of the Ndo . iZro. 9 O 1.95 ceramic coating with yttria dissolved in. Applying a thin layer of 7YSZ on top of the Ndo.iZro. 9 Oi .95 ceramic coating with yttria dissolved in did not significantly change the thermal diffusivity.
• the density of the ceramic coating is about 4.7g/cm 3 , which is less than that of the typical 7YSZ coating (5.0g/cm 3 ). This lower density allows the gas turbine component coated with the ceramic coating to have less coating weight than that currently used for typical 7YSZ coated components.
• the thermal conductivity of Nd 0. iZro. 9 Oi. 95 ceramic coatings with yttria dissolved in is calculated according to their value of thermal diffusivity, density and specific heat, and then is plotted in Fig. 6, which shows the thermal conductivity of the ceramic coating as deposited at a temperature 600°C to 1100°C.
• the ceramic coating as deposited shows a low thermal conductivity of 0.78-1.02 W/mK, which is 46%-47% of the measured thermal conductivity of typical 7YSZ coating (1.65-2.22 W/mK from 600°C to 1100°C).
• the thermal insulation capability of the ceramic coating is primarily attributed to its crystal structure and chemistry. Heat conduction is a motion of carriers of thermal energy. In dielectric ceramic materials, the carriers are lattice vibration, i.e. phonon motion. The high intrinsic point defects of substitutional atoms Nd and oxygen vacancy leads to the reduction in the mean free path length of a phonon.
• Fig. 7 shows the thermal conductivity of the ceramic coatings and typical 7YSZ coating after aging heat treat. Comparing the thermal conductivity of the coatings as deposited in Fig. 6, all the coatings as aged have higher thermal conductivity than those as deposited. This is because that the gaps between the adjacent columns in EBPVD applied thermal barrier coatings will be narrowed or even be closed by sintering at high temperature. The lack of scattering sites of vertical pores will increase thermal conductivity of the coating. However, it is noticeable that the thermal conductivity of the Ndo. 1 Zro. 9 Oi.
• 95 ceramic coatings with yttria dissolved in as aged is still quite low at 1.00 W/mK after aging, which is about 50% of the thermal conductivity of 7YSZ coating as aged.
• a thermal barrier coating is subjected to incident radiation from the hot combustor. Radiation is then absorbed by the soot that is usually covered on the exposed coating due to the combustion environment.
• a translucent coating such as typical yttria stabilized zirconia, permits the energy to be transported internally by radiation, thereby increasing the total energy transfer and acting to increase thermal conductivity.
• the Nd 0 .iZro. O ⁇ . 95 ceramic coating with yttria dissolved in has a sky- blue color, which can reduce the internal radiation transport.
• Ndo. 1 Zro. 9 O 1 . 95 with 2.6 mole % of yttria dissolved in also demonstrates a high resistance to cyclic oxidation.
• the cyclic oxidation test was conducted at 2025°F, one hour cycle, i.e. 7 minutes heat up to 2025°F, soak at 2025°F for 50 minutes, followed by 3 minutes air-forced cooling down to 200°F.
• 7YSZ coated specimens used as a reference were loaded in the same furnace chamber. The specimens were inspected at specified intervals. Six samples of each coating were tested. The lifetime is measured by the number of cycles to failure (spallation of 30% of the coating area).

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