WO1996031293A1 - Method and composite for protection of thermal barrier coating by a sacrificial surface coating - Google Patents
Method and composite for protection of thermal barrier coating by a sacrificial surface coating Download PDFInfo
- Publication number
- WO1996031293A1 WO1996031293A1 PCT/US1996/003684 US9603684W WO9631293A1 WO 1996031293 A1 WO1996031293 A1 WO 1996031293A1 US 9603684 W US9603684 W US 9603684W WO 9631293 A1 WO9631293 A1 WO 9631293A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- thermal barrier
- barrier coating
- coating
- oxide
- stabilized zirconia
- Prior art date
Links
- 239000012720 thermal barrier coating Substances 0.000 title claims abstract description 128
- 238000000576 coating method Methods 0.000 title claims abstract description 68
- 239000011248 coating agent Substances 0.000 title claims abstract description 60
- 238000000034 method Methods 0.000 title claims abstract description 27
- 239000002131 composite material Substances 0.000 title claims abstract description 15
- 239000000203 mixture Substances 0.000 claims abstract description 112
- 239000000356 contaminant Substances 0.000 claims abstract description 75
- 230000008018 melting Effects 0.000 claims abstract description 28
- 238000002844 melting Methods 0.000 claims abstract description 28
- 230000007613 environmental effect Effects 0.000 claims abstract description 25
- 238000001764 infiltration Methods 0.000 claims abstract description 18
- 230000008595 infiltration Effects 0.000 claims abstract description 17
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 claims description 38
- 239000000395 magnesium oxide Substances 0.000 claims description 23
- 230000004888 barrier function Effects 0.000 claims description 22
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 21
- 239000007788 liquid Substances 0.000 claims description 21
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims description 18
- 239000000292 calcium oxide Substances 0.000 claims description 16
- 241000968352 Scandia <hydrozoan> Species 0.000 claims description 15
- HJGMWXTVGKLUAQ-UHFFFAOYSA-N oxygen(2-);scandium(3+) Chemical compound [O-2].[O-2].[O-2].[Sc+3].[Sc+3] HJGMWXTVGKLUAQ-UHFFFAOYSA-N 0.000 claims description 15
- 235000012255 calcium oxide Nutrition 0.000 claims description 14
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 13
- DJOYTAUERRJRAT-UHFFFAOYSA-N 2-(n-methyl-4-nitroanilino)acetonitrile Chemical compound N#CCN(C)C1=CC=C([N+]([O-])=O)C=C1 DJOYTAUERRJRAT-UHFFFAOYSA-N 0.000 claims description 12
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 claims description 11
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 10
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 10
- 229910002076 stabilized zirconia Inorganic materials 0.000 claims description 9
- GSWGDDYIUCWADU-UHFFFAOYSA-N aluminum magnesium oxygen(2-) Chemical compound [O--].[Mg++].[Al+3] GSWGDDYIUCWADU-UHFFFAOYSA-N 0.000 claims description 8
- QDOXWKRWXJOMAK-UHFFFAOYSA-N dichromium trioxide Chemical compound O=[Cr]O[Cr]=O QDOXWKRWXJOMAK-UHFFFAOYSA-N 0.000 claims description 8
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 claims description 8
- 239000000377 silicon dioxide Substances 0.000 claims description 8
- 229910044991 metal oxide Inorganic materials 0.000 claims description 7
- 150000004706 metal oxides Chemical class 0.000 claims description 7
- 239000000758 substrate Substances 0.000 claims description 7
- 229910001233 yttria-stabilized zirconia Inorganic materials 0.000 claims description 7
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims description 6
- 229910002084 calcia-stabilized zirconia Inorganic materials 0.000 claims description 5
- -1 calcium- magnesium-aluminum-silicon oxide Chemical group 0.000 claims description 5
- 229910052742 iron Inorganic materials 0.000 claims description 5
- 229910002085 magnesia-stabilized zirconia Inorganic materials 0.000 claims description 5
- 229910052759 nickel Inorganic materials 0.000 claims description 5
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 4
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims description 4
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims description 4
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 4
- 229910052782 aluminium Inorganic materials 0.000 claims description 4
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 4
- 239000011575 calcium Substances 0.000 claims description 4
- 229910052791 calcium Inorganic materials 0.000 claims description 4
- 230000015556 catabolic process Effects 0.000 claims description 4
- 238000006731 degradation reaction Methods 0.000 claims description 4
- 229910052749 magnesium Inorganic materials 0.000 claims description 4
- 239000011777 magnesium Substances 0.000 claims description 4
- 239000010703 silicon Substances 0.000 claims description 4
- 229910052710 silicon Inorganic materials 0.000 claims description 4
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 claims description 3
- 238000000151 deposition Methods 0.000 claims description 3
- 229910052814 silicon oxide Inorganic materials 0.000 claims description 3
- 239000000956 alloy Substances 0.000 claims 5
- 229910045601 alloy Inorganic materials 0.000 claims 5
- 229910000531 Co alloy Inorganic materials 0.000 claims 2
- 238000004519 manufacturing process Methods 0.000 claims 1
- 229910000480 nickel oxide Inorganic materials 0.000 claims 1
- GNRSAWUEBMWBQH-UHFFFAOYSA-N oxonickel Chemical compound [Ni]=O GNRSAWUEBMWBQH-UHFFFAOYSA-N 0.000 claims 1
- RUDFQVOCFDJEEF-UHFFFAOYSA-N yttrium(III) oxide Inorganic materials [O-2].[O-2].[O-2].[Y+3].[Y+3] RUDFQVOCFDJEEF-UHFFFAOYSA-N 0.000 claims 1
- 230000002939 deleterious effect Effects 0.000 abstract description 2
- 238000007792 addition Methods 0.000 description 10
- 239000003570 air Substances 0.000 description 8
- 238000004455 differential thermal analysis Methods 0.000 description 7
- 239000011253 protective coating Substances 0.000 description 7
- 239000000126 substance Substances 0.000 description 7
- 238000012360 testing method Methods 0.000 description 7
- 239000007921 spray Substances 0.000 description 6
- 239000000463 material Substances 0.000 description 5
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 4
- 230000008859 change Effects 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 238000001816 cooling Methods 0.000 description 3
- 238000005336 cracking Methods 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 230000003647 oxidation Effects 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 2
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 238000005229 chemical vapour deposition Methods 0.000 description 2
- 229910052804 chromium Inorganic materials 0.000 description 2
- 239000011651 chromium Substances 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 230000032798 delamination Effects 0.000 description 2
- 238000004299 exfoliation Methods 0.000 description 2
- 239000000446 fuel Substances 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 239000010410 layer Substances 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 238000005088 metallography Methods 0.000 description 2
- 229910052697 platinum Inorganic materials 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 230000001681 protective effect Effects 0.000 description 2
- 230000002829 reductive effect Effects 0.000 description 2
- 238000004544 sputter deposition Methods 0.000 description 2
- 229910052719 titanium Inorganic materials 0.000 description 2
- 239000010936 titanium Substances 0.000 description 2
- 229910019142 PO4 Inorganic materials 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 150000001340 alkali metals Chemical class 0.000 description 1
- 239000002956 ash Substances 0.000 description 1
- 229910052788 barium Inorganic materials 0.000 description 1
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 description 1
- 238000000339 bright-field microscopy Methods 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 1
- 239000004568 cement Substances 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 238000005524 ceramic coating Methods 0.000 description 1
- 229910010293 ceramic material Inorganic materials 0.000 description 1
- 239000008199 coating composition Substances 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000001351 cycling effect Effects 0.000 description 1
- 238000001446 dark-field microscopy Methods 0.000 description 1
- 238000000280 densification Methods 0.000 description 1
- 210000003298 dental enamel Anatomy 0.000 description 1
- 230000001687 destabilization Effects 0.000 description 1
- 230000003292 diminished effect Effects 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000004453 electron probe microanalysis Methods 0.000 description 1
- 238000004534 enameling Methods 0.000 description 1
- 230000003628 erosive effect Effects 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 239000010881 fly ash Substances 0.000 description 1
- 230000008014 freezing Effects 0.000 description 1
- 238000007710 freezing Methods 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 238000009533 lab test Methods 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 238000002488 metal-organic chemical vapour deposition Methods 0.000 description 1
- 125000002524 organometallic group Chemical group 0.000 description 1
- 239000008188 pellet Substances 0.000 description 1
- 239000012071 phase Substances 0.000 description 1
- 235000021317 phosphate Nutrition 0.000 description 1
- 150000003013 phosphoric acid derivatives Chemical class 0.000 description 1
- 238000005240 physical vapour deposition Methods 0.000 description 1
- 229910052573 porcelain Inorganic materials 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000001902 propagating effect Effects 0.000 description 1
- 239000011241 protective layer Substances 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
- 229910052566 spinel group Inorganic materials 0.000 description 1
- 229910000601 superalloy Inorganic materials 0.000 description 1
- 230000008961 swelling Effects 0.000 description 1
- 238000005382 thermal cycling Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
- B05D3/02—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by baking
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D25/00—Component parts, details, or accessories, not provided for in, or of interest apart from, other groups
- F01D25/007—Preventing corrosion
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D1/00—Processes for applying liquids or other fluent materials
- B05D1/36—Successively applying liquids or other fluent materials, e.g. without intermediate treatment
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B15/00—Layered products comprising a layer of metal
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B15/00—Layered products comprising a layer of metal
- B32B15/01—Layered products comprising a layer of metal all layers being exclusively metallic
-
- 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
- C23C28/04—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 only coatings of inorganic non-metallic material
-
- 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
- C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
- C23C4/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
-
- 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
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02C—GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS
- F02C7/00—Features, components parts, details or accessories, not provided for in, or of interest apart form groups F02C1/00 - F02C6/00; Air intakes for jet-propulsion plants
- F02C7/30—Preventing corrosion or unwanted deposits in gas-swept spaces
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T50/00—Aeronautics or air transport
- Y02T50/60—Efficient propulsion technologies, e.g. for aircraft
Definitions
- the present invention relates to a method and composite for protecting thermal barrier coatings deposited on gas turbine and other heat engine parts from the deleterious effects of environmental contaminants.
- the invention relates to a method and composite using a reactive sacrificial oxide coating which reacts with the contaminant composition formed from the environmental contaminants.
- Thermal barrier coatings are deposited onto gas turbine and other heat engine parts to reduce heat flow and to limit the operating temperature of metal parts. These coatings generally are a ceramic material, such as chemically stabilized zirconia. Yttria-stabilized zirconia, scandia-stabilized zirconia, calcia-stabilized zirconia, and magnesia- stabilized zirconia are contemplated as thermal barrier coatings.
- the thermal barrier coating of choice is a yttria-stabilized zirconia ceramic coating.
- a typical thermal barrier coating comprises about 8 weight percent yttria-92 weight percent zirconia.
- thermal barrier coating depends on the application, but generally ranges between about 5-60 mils thick for high temperature engine parts.
- Metal parts provided with thermal barrier coatings can be made from nickel, cobalt, and iron based superalloys. The process is especially suited for parts and hardware used in turbines. Examples of turbine parts would be turbine blades, buckets, nozzles, combustion liners, and the like.
- Thermal barrier coatings are a key element in current and future gas turbine engine designs expected to operate at high temperatures which produce high thermal barrier coating surface temperatures .
- the ideal system for a hot high temperature engine part consists of a strain-tolerant thermal barrier ceramic layer deposited onto a bond coat which exhibits good corrosion resistance and closely matched thermal expansion coefficients.
- thermal barrier coated engine parts can be susceptible to various modes of damage, including erosion, oxidation, and attack from environmental contaminants. At temperatures of engine operation adherence of these environmental contaminants on the hot thermal barrier coated surface can cause damage to the thermal barrier coating. Environmental contaminants form compositions, which are liquid at the surface temperatures of thermal barrier coatings .
- Molten contaminant compositions can dissolve the thermal barrier coating or can infiltrate its pores and openings, initiating and propagating cracks causing delamination and loss of thermal barrier coating material.
- Some environmental contaminant compositions that deposit on thermal barrier coated surfaces contain oxides of calcium, magnesium, aluminum, silicon, and mixtures thereof. These oxides combine to form contaminant compositions comprising calcium- magnesium-aluminum-silicon-oxide systems (Ca-Mg-Al-Si- 0), herein referred to as CMAS. Damage to thermal barrier coatings occurs when the molten CMAS infiltrates the thermal barrier coating. After infiltration and upon cooling, the molten CMAS, or other molten contaminant composition, solidifies. The stress build up in the thermal barrier coating is sufficient to cause spallation of the coating material and loss of the thermal protection that it provides to the underlying part.
- CMAS calcium- magnesium-aluminum-silicon-oxide systems
- the present invention satisfies this need by protecting a thermal barrier coating from degradation by environmental contaminant compositions which form on and adhere to a surface of a thermal barrier coated part.
- the method of the invention comprises depositing a reactive or sacrificial oxide coating on the surface of thermal barrier coating, in an effective amount, so that the oxide coating reacts with the contaminant composition at the operating temperature of said thermal barrier coating and raises the melting temperature or viscosity of the contaminant composition as it forms on the surface.
- the present invention also satisfies this need by providing a composite comprising a thermal barrier coating on a part with a continuous sacrificial oxide coating adjacent to an outer surface of the thermal barrier coating.
- the invention also includes a protected thermal barrier coated part comprising a part with a thermal barrier coating on said part and a single protective layer of a sacrificial oxide coating on an outer surface of said thermal barrier coating.
- the composite thermal barrier coating according to the present invention also comprises a substrate, bond coat, with a thermal barrier coating and a sacrificial oxide coating.
- Environmental contaminants are materials that exist in the environment and are ingested into engines, from air and fuel sources, and impurities and oxidation products of engine components, such as iron oxide.
- operating temperature means the surface temperature of the thermal barrier coating during its operation in a given application, such as a gas turbine engine. Such temperatures are above room temperature, and generally are above 500°C. High temperature operation of thermal barrier coating parts is usually above about 1000°C.
- a composite comprising a thermal barrier coated part with an outer sacrificial oxide coating has decreased damage from environmental contaminants that form molten contaminant compositions on the surface of the thermal barrier coating at operating temperatures. It has also been discovered that by applying a sacrificial oxide coating that reacts with environmental contaminants and resulting contaminant compositions encountered on surfaces of thermal barrier coated parts during service operation, the melting temperature or viscosity of the contaminant composition can be increased. As a result, the contaminant composition does not become molten and infiltration or viscous flow of the mixture into the thermal barrier coating is curtailed. This reduces damage to the thermal barrier coating.
- Increasing the melting temperature and viscosity of the contaminant composition reduces infiltration into the thermal barrier coating, thereby decreasing the degradation of the thermal barrier coating.
- the composition does not become liquid at the operating temperature of the thermal barrier coating. Infiltration or viscous flow of the contaminant composition into thermal barrier coating cracks, openings, and pores is diminished.
- This invention also protects the thermal barrier coating from dissolution or spallation due to chemical and mechanical attack by the contaminant composition. This enhances the life of the thermal barrier coated part and thus, reduces thermal barrier coated part failure.
- Sources of environmental contaminants include, but are not limited to, sand, dirt, volcanic ash, fly ash, cement, runway dust, substrate impurities, fuel and air sources, oxidation products from engine components, and the like.
- the environmental contaminants adhere to the surfaces of thermal barrier coated parts. At the operating temperatures of the thermal barrier coating, the environmental contaminants then form contaminant compositions on surfaces of the thermal barrier coating which may have melting ranges or temperatures at or below the operating temperature.
- the environmental contaminant may include magnesium, calcium, aluminum, silicon, chromium, iron, nickel, barium, titanium, alkali metals, and compounds thereof, to mention a few.
- the environmental contaminants may be oxides, phosphates, carbonates, salts, and mixtures thereof.
- the chemical composition of the contaminant composition corresponds to the composition of the environmental contaminants from which it is formed. For example, at operational temperatures of about 1000°C or higher, the contaminant composition corresponds to compositions in the calcium-magnesium- aluminum-silicon oxide systems or CMAS.
- the environmental contaminant compositions known as CMAS comprise primarily a mixture of magnesium oxide (MgO) , calcium oxide (CaO) , aluminum oxide (Al 2 ⁇ 3 ), and silicon oxide (Si ⁇ 2 ..
- MgO magnesium oxide
- CaO calcium oxide
- Al 2 ⁇ 3 aluminum oxide
- Other elements, such as nickel, iron, titanium, and chromium, may be present in the CMAS in minor amounts when these elements or their compounds are present in the environmental contaminants.
- a minor amount is an amount less than about ten weight percent of the total amount of contaminant composition present.
- the protective coatings of this invention can be described as sacrificial or reactive in that they protect thermal barrier coatings by undergoing chemical or physical changes when in contact with a liquid contaminant composition.
- the character of the protective coating is sacrificed.
- the result of the change is to increase either the viscosity or the physical state of the contaminant composition, e.g., liquid CMAS, by dissolving in the composition or reacting with it, to form a by-product material which is not liquid or at least more viscous than the original CMAS.
- Such a sacrificial or reactive coating is an outer oxide coating, usually of a metal oxide, deposited on the outer surface of the thermal barrier coating that reacts chemically with the contaminant composition at the surface temperature of the thermal barrier coating.
- the chemical reaction is one in which the sacrificial oxide coating is consumed, at least partially, and elevates the melting temperature or viscosity of the contaminant composition.
- the melting temperature of the contaminant composition is preferably increased by at least about 10°C, and most preferably about 50-100°C, above the surface temperature of the thermal barrier coating during its operation.
- the composition of the sacrificial oxide coating is in part based on the composition of the environmental contaminants and the surface temperature of the thermal barrier coating during operation.
- the sacrificial oxide coating contains an element or elements that are present in the liquid contaminant composition.
- Suitable sacrificial oxide coatings that react with the CMAS composition to raise its melting temperature or viscosity include, but are not limited to, alumina, magnesia, chromia, calcia, scandia, calcium zirconate, silica, spinels such as magnesium aluminum oxide, and mixtures thereof.
- a sacrificial oxide coating such as scandia
- a sacrificial oxide coating such as scandia
- to raise the CMAS melting temperature from 1190°C to greater than 1300°C about 10-20 weight percent of scandia is used for the sacrificial oxide coating.
- the protective oxide coating is applied to the thermal barrier coating in an amount sufficient to effectively elevate the melting temperature or the viscosity of substantially all of the liquid contaminant formed.
- the thermal barrier coating As little as about one weight percent of the oxide coating based on the total weight of the contaminant composition present on the surface of the thermal barrier coating can help prevent infiltration of molten contaminant compositions into the thermal barrier coating.
- about 10-20 weight percent of the sacrificial oxide coating is deposited on the thermal barrier coating.
- the amount of the sacrificial oxide coating deposited may be up to fifty weight percent or a 1:1 ratio of oxide coating to liquid contaminant.
- the sacrificial oxide coating can be deposited on the thermal barrier coating by coating methods known in the art, such as sol-gel, sputtering, air plasma spray, organo-metallic chemical vapor deposition, physical vapor deposition, chemical vapor deposition, and the like. Thicknesses of the sacrificial oxide coating can vary from about 0.2 micrometers to about 250 micrometers. The preferred thickness is about 2-125 micrometers. The thickness of the oxide coating is at least in part, determined by the chemistry of the particular oxide coating, the operating temperature of the thermal barrier coating, and the amount and composition of the contaminant. If thick sacrificial oxide coatings are required, i.e., about 125 micrometers or more, a compositionally graded deposit can be used to keep internal stresses minimized in order that delamination of the sacrificial coating does not occur.
- CMAS composition For purposes of illustrating the use of a specific sacrificial oxide coating, as well as imparting an understanding of the present invention, the reaction of CMAS composition with the sacrificial oxide coating on a thermal barrier coating is described at operating temperatures of about 1200°C or higher.
- the chemical composition of the CMAS composition was determined by electron microprobe analysis of infiltrated deposits found on thermal barrier coated engine parts where deposit-induced damage to the thermal barrier coating had been observed. Analysis indicated that 127 micron (5 mils) of CMAS-like deposits (-34 mg/cm-2 assuming a density of 2.7 g/cm ⁇ ) can form on thermal barrier coating surfaces.
- the CMAS deposits evaluated were typically in the compositional range (weight %) : 5-35% CaO, 2- 35% MgO, 5-15% AI2O3, 5-55% Si ⁇ 2, 0-5% NiO, 5-10%
- An average composition for such deposits (weight %: 28.7% CaO, 6.4% MgO, 11.1% AI2O3, 43.7% Si ⁇ 2, 1.9% NiO, 8.3% Fe 2 03> was synthesized in the laboratory and used as a standard CMAS for the purpose of evaluating protective coatings. Differential thermal analysis of actual CMAS deposits and the synthesized CMAS indicated that the onset of melting occurs at about 1190°C with the maximum of the melting peak occurring at about 1260°C. Thermal testing of candidate protective coatings for thermal barrier coatings against the laboratory synthesized CMAS composition were carried out at about 1260°C.
- Viscosity data on a similar CMAS composition indicates that the viscosity of CMAS is about 4 Pa»s (Pascal second) at 1260°C. This fluid phase infiltrates the thermal barrier coating and causes damage either by freezing-induced spallation or by high temperature chemical attack induced destabilization. Laboratory experiments with unprotected thermal barrier coatings indicate that, under isothermal conditions, 8mg CMAS/c ⁇ .2 is sufficient to cause entire thermal barrier coating layers to spall off.
- the surface temperature of the thermal barrier coating during operation is about 1200°C
- the melting temperature of the CMAS composition should be raised at least 10°C higher than the surface temperature of the thermal barrier coating during its operation.
- DTA differential thermal analysis
- thermodynamic calculation to assess the ability of candidate sacrificial materials to react with CMAS and increase the melting temperature such that infiltration of the CMAS does not occur into the thermal barrier coating during service.
- Viscosity measurements were used to assess the ability of sacrificial oxide coatings to react with CMAS, to increase the liquid phase viscosity, and thereby, to limit physical infiltration into the thermal barrier coating microstrueture.
- Candidate sacrificial oxide coating compositions were deposited on thermal barrier coatings and assessed for CMAS infiltration resistance using metallography, SEM and electron microprobe chemical analysis. The above testing was conducted under laboratory furnace test conditions (isothermal) .
- Sacrificial reactive oxide coatings that were deposited by the sol-gel, air plasma spray, sputtering, and MOCVD methods were: scandia, calcium zirconate, calcium oxide (CaO) , aluminum oxide (AI 2 O 3 ), magnesium oxide (MgO), and silicon oxide (Si0 2 ) .
- the effectiveness of protective coatings in preventing CMAS-infiltration-induced thermal barrier coating damage was tested by comparing the infiltration resistance of protected and non-protected thermal barrier coated substrates which were thermally cycled in the presence of surface deposits of CMAS.
- 8mg/cm*2 of ground pre-reacted CMAS was deposited on masked areas of the thermal barrier coated substrates.
- a thermal cycle consisted of heating the samples to 1260°C in 10 minutes, holding it at 1260°C for 10 minutes, followed by cooling it to room temperature in 30 minutes. After each cycle the samples were inspected with the unaided eye and at 50x using a stereo microscope. This cycle was repeated several times. After completion of thermal testing, the samples were sectioned, metallographically polished, and inspected using bright field and dark field optical microscopy.
- Example 1 demonstrates the effect of CMAS on a thermal barrier coated part without a sacrificial oxide protective coating.
- Non-protected thermal barrier coating samples tested in the above-mentioned fashion exhibit visible CMAS induced thermal barrier coating swelling and cracking (visible on sample edges under the stereomicroscope) .
- Metallographic preparation and inspection of the non-protected samples shows CMAS induced thermal barrier coating densification, cracking and exfoliation.
- EXAMPLE 3 Differential thermal analysis found that magnesia or calcia additions increased the melting temperatures for CMAS compositions when 1:1 by weight additions were made. Twenty weight percent additions - 13 - of magnesia or calcia cause the differential thermal analysis curves for CMAS compositions to exhibit two separate melting peaks: at 1254°C and at 1318°C for magnesia, and 1230°C and 1331°C for calcia. Thermal barrier coatings protected with magnesia or calcia coatings exhibited less CMAS composition-induced exfoliation than unprotected thermal barrier coating samples when exposed to 8 mg/cm 2 CMAS compositions during furnace cycle testing. A 5 mil thick magnesium oxide coating was air plasma spray coated on a thermal barrier coating sample and tested using the above described method.
- EAMPLE 4 A 3 mil thick calcium zirconate coating was air plasma spray coated on a thermal barrier coating sample and tested using the method described in example 1. After thermally cycling the coating with the addition of 8 mg/cm 2 CMAS to 1260°C, metallography showed that CMAS composition was retained on top of the thermal barrier coating, and there was no apparent infiltration into the thermal barrier coating.
- alumina additions increase the CMAS composition melting temperature upon heating when 1:1 by weight additions of alumina to the CMAS composition are made.
- One to one additions elevate the onset of melting for CMAS compositions to a temperature greater than 1345°C.
- a 5 mil air plasma spray deposited film of alumina minimized the infiltration of 8 mg/cm 2 CMAS composition after heat treatment at 1260°C for 1 hour.
- EXAMPLE 6 The ability of secondary protective oxides to increase the viscosity was tested. For a given exposure time, an increase in CMAS viscosity will decrease the infiltration depth into the thermal barrier coating. Survey studies of viscosity changes in CMAS resulting from oxide additions were made. Simplistic viscosity type measurements utilized in testing of porcelain enamels were employed for ranking purposes. In the enameling test, pellets made from mixtures of CMAS with varying amounts of candidate oxides were placed on a horizontal platinum sheet and melted. The platinum sheet was rotated to a vertical position for a precise amount of time (to allow viscous flow) and then rotated back to a horizontal position (to stop viscous flow) and removed from the furnace.
- the approximate viscosity can be calculated from the length of the flow line and the flow time.
- the relative change in CMAS viscosity with oxide addition can be determined by measuring the change in flow line length with the addition of various oxides.
- Candidate oxides which increased the CMAS viscosity (among them alumina, magnesia, calcia, and calcium zirconate) were then deposited on thermal barrier coated substrates and thermally tested with CMAS deposits. The results of the alumina, magnesia, and calcium zirconate protective coatings are described in examples 2, 3 and 4.
- this invention also is a method for protecting a thermal barrier coating against damage caused by a liquid composition formed from environmental contaminants at operating temperatures of the thermal barrier coating which comprises forming on a surface of the thermal barrier coating a sacrificial metal oxide coating comprising at least one metal oxide that reacts with said liquid composition and upon contact with said liquid composition raises a melting temperature or viscosity of said liquid composition above a surface temperature of the thermal barrier coating. The melting point of the liquid composition is increased.
- the practice of this invention makes it possible to extend the effective life of gas turbine engine thermal barrier coatings at a specific set of operating parameters including operating temperature and operating environment. It also provides a means to provide for engine designs which impose increased thermal burdens on thermal barrier coatings such as reduced cooling of thermal barrier coated parts or exposure of such parts to higher temperature input, i.e., effective increase of operating temperatures for the engine system. Accordingly, the practice of this invention provides for substantial enhancement of the functions of currently available thermal barrier coatings under more rigorous thermal assault as demands for performance escalate.
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Abstract
A method and composite for protecting thermal barrier coatings deposited on engine parts from the deleterious effects of environmental contaminants at high temperatures are given. The method and composite utilize a sacrificially consumed oxide coating with the thermal barrier coating, where the consumption of the oxide coating increases the melting temperature of a contaminant composition above the surface temperature of the thermal barrier coating, or increases the viscosity of the contaminant composition to prevent its infiltration into the thermal barrier coating.
Description
METHOD AND COMPOSITE FOR
PROTECTION OF THERMAL BARRIER
COATING BY A SACRIFICIAL SURFACE
COATING
FIELD OF THE INVENTION The present invention relates to a method and composite for protecting thermal barrier coatings deposited on gas turbine and other heat engine parts from the deleterious effects of environmental contaminants. In particular, the invention relates to a method and composite using a reactive sacrificial oxide coating which reacts with the contaminant composition formed from the environmental contaminants.
BACKGROUND OF THE INVENTION Thermal barrier coatings are deposited onto gas turbine and other heat engine parts to reduce heat flow and to limit the operating temperature of metal parts. These coatings generally are a ceramic material, such as chemically stabilized zirconia. Yttria-stabilized zirconia, scandia-stabilized zirconia, calcia-stabilized zirconia, and magnesia- stabilized zirconia are contemplated as thermal barrier coatings. The thermal barrier coating of choice is a yttria-stabilized zirconia ceramic coating. A typical thermal barrier coating comprises about 8 weight percent yttria-92 weight percent zirconia. The thickness of a thermal barrier coating depends on the application, but generally ranges between about 5-60 mils thick for high temperature engine parts. Metal parts provided with thermal barrier coatings can be made from nickel, cobalt, and iron
based superalloys. The process is especially suited for parts and hardware used in turbines. Examples of turbine parts would be turbine blades, buckets, nozzles, combustion liners, and the like. Thermal barrier coatings are a key element in current and future gas turbine engine designs expected to operate at high temperatures which produce high thermal barrier coating surface temperatures . The ideal system for a hot high temperature engine part consists of a strain-tolerant thermal barrier ceramic layer deposited onto a bond coat which exhibits good corrosion resistance and closely matched thermal expansion coefficients.
Under service conditions, thermal barrier coated engine parts can be susceptible to various modes of damage, including erosion, oxidation, and attack from environmental contaminants. At temperatures of engine operation adherence of these environmental contaminants on the hot thermal barrier coated surface can cause damage to the thermal barrier coating. Environmental contaminants form compositions, which are liquid at the surface temperatures of thermal barrier coatings .
Chemical and mechanical interactions occur between the contaminant compositions and the thermal barrier coatings. Molten contaminant compositions can dissolve the thermal barrier coating or can infiltrate its pores and openings, initiating and propagating cracks causing delamination and loss of thermal barrier coating material.
Some environmental contaminant compositions that deposit on thermal barrier coated surfaces contain oxides of calcium, magnesium, aluminum, silicon, and mixtures thereof. These oxides combine to form contaminant compositions comprising calcium-
magnesium-aluminum-silicon-oxide systems (Ca-Mg-Al-Si- 0), herein referred to as CMAS. Damage to thermal barrier coatings occurs when the molten CMAS infiltrates the thermal barrier coating. After infiltration and upon cooling, the molten CMAS, or other molten contaminant composition, solidifies. The stress build up in the thermal barrier coating is sufficient to cause spallation of the coating material and loss of the thermal protection that it provides to the underlying part.
There is a need to reduce or prevent the damage to thermal barrier coatings caused by the reaction or infiltration of molten contaminant compositions at the operating temperature of the engine. This can be accomplished by raising the melting temperature or viscosity of a contaminant composition when it forms on the hot surfaces of thermal barrier coated parts with a sacrificial oxide coating so that the contaminant composition does not form a reactive liquid or flow into the thermal barrier coating.
SUMMARY OF THE INVENTION The present invention satisfies this need by protecting a thermal barrier coating from degradation by environmental contaminant compositions which form on and adhere to a surface of a thermal barrier coated part. The method of the invention comprises depositing a reactive or sacrificial oxide coating on the surface of thermal barrier coating, in an effective amount, so that the oxide coating reacts with the contaminant composition at the operating temperature of said thermal barrier coating and raises the melting temperature or viscosity of the contaminant composition as it forms on the surface.
The present invention also satisfies this need by providing a composite comprising a thermal barrier coating on a part with a continuous sacrificial oxide coating adjacent to an outer surface of the thermal barrier coating. The invention also includes a protected thermal barrier coated part comprising a part with a thermal barrier coating on said part and a single protective layer of a sacrificial oxide coating on an outer surface of said thermal barrier coating. The composite thermal barrier coating according to the present invention also comprises a substrate, bond coat, with a thermal barrier coating and a sacrificial oxide coating.
Environmental contaminants are materials that exist in the environment and are ingested into engines, from air and fuel sources, and impurities and oxidation products of engine components, such as iron oxide.
The term "operating temperature" means the surface temperature of the thermal barrier coating during its operation in a given application, such as a gas turbine engine. Such temperatures are above room temperature, and generally are above 500°C. High temperature operation of thermal barrier coating parts is usually above about 1000°C.
DESCRIPTION OF THE INVENTION It has been discovered that a composite comprising a thermal barrier coated part with an outer sacrificial oxide coating has decreased damage from environmental contaminants that form molten contaminant compositions on the surface of the thermal barrier coating at operating temperatures. It has also been discovered that by applying a sacrificial oxide coating that reacts with environmental
contaminants and resulting contaminant compositions encountered on surfaces of thermal barrier coated parts during service operation, the melting temperature or viscosity of the contaminant composition can be increased. As a result, the contaminant composition does not become molten and infiltration or viscous flow of the mixture into the thermal barrier coating is curtailed. This reduces damage to the thermal barrier coating. Increasing the melting temperature and viscosity of the contaminant composition reduces infiltration into the thermal barrier coating, thereby decreasing the degradation of the thermal barrier coating. As a result of the sacrificial oxide coating being consumed or dissolved into the contaminant composition, the composition does not become liquid at the operating temperature of the thermal barrier coating. Infiltration or viscous flow of the contaminant composition into thermal barrier coating cracks, openings, and pores is diminished.
This invention also protects the thermal barrier coating from dissolution or spallation due to chemical and mechanical attack by the contaminant composition. This enhances the life of the thermal barrier coated part and thus, reduces thermal barrier coated part failure.
Sources of environmental contaminants include, but are not limited to, sand, dirt, volcanic ash, fly ash, cement, runway dust, substrate impurities, fuel and air sources, oxidation products from engine components, and the like. The environmental contaminants adhere to the surfaces of thermal barrier coated parts. At the operating temperatures of the thermal barrier coating, the environmental contaminants then form contaminant
compositions on surfaces of the thermal barrier coating which may have melting ranges or temperatures at or below the operating temperature.
In addition, the environmental contaminant may include magnesium, calcium, aluminum, silicon, chromium, iron, nickel, barium, titanium, alkali metals, and compounds thereof, to mention a few. The environmental contaminants may be oxides, phosphates, carbonates, salts, and mixtures thereof. The chemical composition of the contaminant composition corresponds to the composition of the environmental contaminants from which it is formed. For example, at operational temperatures of about 1000°C or higher, the contaminant composition corresponds to compositions in the calcium-magnesium- aluminum-silicon oxide systems or CMAS. Generally, the environmental contaminant compositions known as CMAS comprise primarily a mixture of magnesium oxide (MgO) , calcium oxide (CaO) , aluminum oxide (Al2θ3), and silicon oxide (Siθ2.. Other elements, such as nickel, iron, titanium, and chromium, may be present in the CMAS in minor amounts when these elements or their compounds are present in the environmental contaminants. A minor amount is an amount less than about ten weight percent of the total amount of contaminant composition present.
The protective coatings of this invention can be described as sacrificial or reactive in that they protect thermal barrier coatings by undergoing chemical or physical changes when in contact with a liquid contaminant composition. Thus, the character of the protective coating is sacrificed. The result of the change is to increase either the viscosity or the physical state of the contaminant composition, e.g., liquid CMAS, by dissolving in the composition or
reacting with it, to form a by-product material which is not liquid or at least more viscous than the original CMAS.
Such a sacrificial or reactive coating is an outer oxide coating, usually of a metal oxide, deposited on the outer surface of the thermal barrier coating that reacts chemically with the contaminant composition at the surface temperature of the thermal barrier coating. The chemical reaction is one in which the sacrificial oxide coating is consumed, at least partially, and elevates the melting temperature or viscosity of the contaminant composition. The melting temperature of the contaminant composition is preferably increased by at least about 10°C, and most preferably about 50-100°C, above the surface temperature of the thermal barrier coating during its operation.
The composition of the sacrificial oxide coating is in part based on the composition of the environmental contaminants and the surface temperature of the thermal barrier coating during operation. Usually, the sacrificial oxide coating contains an element or elements that are present in the liquid contaminant composition. Suitable sacrificial oxide coatings that react with the CMAS composition to raise its melting temperature or viscosity, include, but are not limited to, alumina, magnesia, chromia, calcia, scandia, calcium zirconate, silica, spinels such as magnesium aluminum oxide, and mixtures thereof.
For instance, it has been found that a sacrificial oxide coating, such as scandia, can be effective in an amount of about 1 weight percent of the total CMAS composition present. Preferably, to raise the CMAS melting temperature from 1190°C to
greater than 1300°C, about 10-20 weight percent of scandia is used for the sacrificial oxide coating.
The protective oxide coating is applied to the thermal barrier coating in an amount sufficient to effectively elevate the melting temperature or the viscosity of substantially all of the liquid contaminant formed.
As little as about one weight percent of the oxide coating based on the total weight of the contaminant composition present on the surface of the thermal barrier coating can help prevent infiltration of molten contaminant compositions into the thermal barrier coating. Preferably, about 10-20 weight percent of the sacrificial oxide coating is deposited on the thermal barrier coating. In some instances, the amount of the sacrificial oxide coating deposited may be up to fifty weight percent or a 1:1 ratio of oxide coating to liquid contaminant.
The sacrificial oxide coating can be deposited on the thermal barrier coating by coating methods known in the art, such as sol-gel, sputtering, air plasma spray, organo-metallic chemical vapor deposition, physical vapor deposition, chemical vapor deposition, and the like. Thicknesses of the sacrificial oxide coating can vary from about 0.2 micrometers to about 250 micrometers. The preferred thickness is about 2-125 micrometers. The thickness of the oxide coating is at least in part, determined by the chemistry of the particular oxide coating, the operating temperature of the thermal barrier coating, and the amount and composition of the contaminant. If thick sacrificial oxide coatings are required, i.e., about 125 micrometers or more, a compositionally graded deposit can be used to keep internal stresses
minimized in order that delamination of the sacrificial coating does not occur.
For purposes of illustrating the use of a specific sacrificial oxide coating, as well as imparting an understanding of the present invention, the reaction of CMAS composition with the sacrificial oxide coating on a thermal barrier coating is described at operating temperatures of about 1200°C or higher. The chemical composition of the CMAS composition was determined by electron microprobe analysis of infiltrated deposits found on thermal barrier coated engine parts where deposit-induced damage to the thermal barrier coating had been observed. Analysis indicated that 127 micron (5 mils) of CMAS-like deposits (-34 mg/cm-2 assuming a density of 2.7 g/cm^) can form on thermal barrier coating surfaces. The CMAS deposits evaluated were typically in the compositional range (weight %) : 5-35% CaO, 2- 35% MgO, 5-15% AI2O3, 5-55% Siθ2, 0-5% NiO, 5-10%
Fe2θ3, however the content of the ubiquitous Fβ2θ3 can be as large as 75 wt%. An average composition for such deposits (weight %: 28.7% CaO, 6.4% MgO, 11.1% AI2O3, 43.7% Siθ2, 1.9% NiO, 8.3% Fe203> was synthesized in the laboratory and used as a standard CMAS for the purpose of evaluating protective coatings. Differential thermal analysis of actual CMAS deposits and the synthesized CMAS indicated that the onset of melting occurs at about 1190°C with the maximum of the melting peak occurring at about 1260°C. Thermal testing of candidate protective coatings for thermal barrier coatings against the laboratory synthesized CMAS composition were carried out at about 1260°C.
Viscosity data on a similar CMAS composition indicates that the viscosity of CMAS is about 4 Pa»s (Pascal second) at 1260°C. This fluid phase infiltrates the thermal barrier coating and causes damage either by freezing-induced spallation or by high temperature chemical attack induced destabilization. Laboratory experiments with unprotected thermal barrier coatings indicate that, under isothermal conditions, 8mg CMAS/cπ.2 is sufficient to cause entire thermal barrier coating layers to spall off.
In the practice of this invention, if the surface temperature of the thermal barrier coating during operation is about 1200°C, then it is preferred to increase the melting temperature of the CMAS composition to at least about 1210°C, and most preferably, to increase the CMAS melting temperature to about 1260-1310°C. The melting temperature of the CMAS composition should be raised at least 10°C higher than the surface temperature of the thermal barrier coating during its operation.
The following examples further serve to describe the invention.
EXAMPLES
Sacrificial oxide coatings on thermal barrier coated parts were investigated to prevent the infiltration of environmentally deposited mixtures of oxides of calcium, magnesium, aluminum, and silicon (CMAS) .
Studies were conducted using differential thermal analysis (DTA) and thermodynamic calculation to assess the ability of candidate sacrificial materials to react with CMAS and increase the melting temperature such that infiltration of the CMAS does
not occur into the thermal barrier coating during service. Viscosity measurements were used to assess the ability of sacrificial oxide coatings to react with CMAS, to increase the liquid phase viscosity, and thereby, to limit physical infiltration into the thermal barrier coating microstrueture.
Candidate sacrificial oxide coating compositions were deposited on thermal barrier coatings and assessed for CMAS infiltration resistance using metallography, SEM and electron microprobe chemical analysis. The above testing was conducted under laboratory furnace test conditions (isothermal) .
Sacrificial reactive oxide coatings that were deposited by the sol-gel, air plasma spray, sputtering, and MOCVD methods were: scandia, calcium zirconate, calcium oxide (CaO) , aluminum oxide (AI2O3), magnesium oxide (MgO), and silicon oxide (Si02) .
The effectiveness of protective coatings in preventing CMAS-infiltration-induced thermal barrier coating damage was tested by comparing the infiltration resistance of protected and non-protected thermal barrier coated substrates which were thermally cycled in the presence of surface deposits of CMAS. In these experiments, 8mg/cm*2 of ground pre-reacted CMAS was deposited on masked areas of the thermal barrier coated substrates. A thermal cycle consisted of heating the samples to 1260°C in 10 minutes, holding it at 1260°C for 10 minutes, followed by cooling it to room temperature in 30 minutes. After each cycle the samples were inspected with the unaided eye and at 50x using a stereo microscope. This cycle was repeated several times. After completion of thermal testing, the samples were sectioned,
metallographically polished, and inspected using bright field and dark field optical microscopy.
EXAMPLE 1 Example 1 demonstrates the effect of CMAS on a thermal barrier coated part without a sacrificial oxide protective coating. Non-protected thermal barrier coating samples tested in the above-mentioned fashion exhibit visible CMAS induced thermal barrier coating swelling and cracking (visible on sample edges under the stereomicroscope) . Metallographic preparation and inspection of the non-protected samples shows CMAS induced thermal barrier coating densification, cracking and exfoliation.
EXAMPLE 2 Differential thermal analysis experiments found that about 10 weight percent of scandia in CMAS raises the melting temperature of the CMAS composition from 1190°C to 1300°C. Therefore, a 1 mil thick scandia coating was air plasma spray deposited on a thermal barrier coated substrate. Eight mg/cm2 CMAS was deposited on the top surface of the scandia protected thermal barrier coating. Thermal cycling to 1260°C showed that scandia reduced CMAS infiltration into the thermal barrier coating. There were large droplets of CMAS remaining on top of the sample. At 20-50x magnification there were no normally observed CMAS induced edge cracks in the thermal barrier coating.
EXAMPLE 3 Differential thermal analysis found that magnesia or calcia additions increased the melting temperatures for CMAS compositions when 1:1 by weight additions were made. Twenty weight percent additions
- 13 - of magnesia or calcia cause the differential thermal analysis curves for CMAS compositions to exhibit two separate melting peaks: at 1254°C and at 1318°C for magnesia, and 1230°C and 1331°C for calcia. Thermal barrier coatings protected with magnesia or calcia coatings exhibited less CMAS composition-induced exfoliation than unprotected thermal barrier coating samples when exposed to 8 mg/cm2 CMAS compositions during furnace cycle testing. A 5 mil thick magnesium oxide coating was air plasma spray coated on a thermal barrier coating sample and tested using the above described method. Eight mg/cm2 of the CMAS composition was applied to the magnesia coated thermal barrier coating. The CMAS composition did not infiltrate the thermal barrier coating extensively after a thermal cycle to 1260°C. No CMAS induced edge cracking of the thermal barrier coating was observed at a magnification of 20-50x in the CMAS affected area.
EAMPLE 4 A 3 mil thick calcium zirconate coating was air plasma spray coated on a thermal barrier coating sample and tested using the method described in example 1. After thermally cycling the coating with the addition of 8 mg/cm2 CMAS to 1260°C, metallography showed that CMAS composition was retained on top of the thermal barrier coating, and there was no apparent infiltration into the thermal barrier coating.
SXJ FkE 5 Differential thermal analysis experiments found that alumina additions increase the CMAS composition melting temperature upon heating when 1:1 by weight additions of alumina to the CMAS composition are made. One to one additions elevate the onset of
melting for CMAS compositions to a temperature greater than 1345°C. For example, a 5 mil air plasma spray deposited film of alumina minimized the infiltration of 8 mg/cm2 CMAS composition after heat treatment at 1260°C for 1 hour.
EXAMPLE 6 The ability of secondary protective oxides to increase the viscosity was tested. For a given exposure time, an increase in CMAS viscosity will decrease the infiltration depth into the thermal barrier coating. Survey studies of viscosity changes in CMAS resulting from oxide additions were made. Simplistic viscosity type measurements utilized in testing of porcelain enamels were employed for ranking purposes. In the enameling test, pellets made from mixtures of CMAS with varying amounts of candidate oxides were placed on a horizontal platinum sheet and melted. The platinum sheet was rotated to a vertical position for a precise amount of time (to allow viscous flow) and then rotated back to a horizontal position (to stop viscous flow) and removed from the furnace. The approximate viscosity can be calculated from the length of the flow line and the flow time. The relative change in CMAS viscosity with oxide addition can be determined by measuring the change in flow line length with the addition of various oxides. Candidate oxides which increased the CMAS viscosity (among them alumina, magnesia, calcia, and calcium zirconate) were then deposited on thermal barrier coated substrates and thermally tested with CMAS deposits. The results of the alumina, magnesia, and calcium zirconate protective coatings are described in examples 2, 3 and 4.
It is pointed out that this invention also is a method for protecting a thermal barrier coating against damage caused by a liquid composition formed from environmental contaminants at operating temperatures of the thermal barrier coating which comprises forming on a surface of the thermal barrier coating a sacrificial metal oxide coating comprising at least one metal oxide that reacts with said liquid composition and upon contact with said liquid composition raises a melting temperature or viscosity of said liquid composition above a surface temperature of the thermal barrier coating. The melting point of the liquid composition is increased.
The practice of this invention makes it possible to extend the effective life of gas turbine engine thermal barrier coatings at a specific set of operating parameters including operating temperature and operating environment. It also provides a means to provide for engine designs which impose increased thermal burdens on thermal barrier coatings such as reduced cooling of thermal barrier coated parts or exposure of such parts to higher temperature input, i.e., effective increase of operating temperatures for the engine system. Accordingly, the practice of this invention provides for substantial enhancement of the functions of currently available thermal barrier coatings under more rigorous thermal assault as demands for performance escalate.
Claims
1. A method for protecting a thermal barrier coating from degradation by environmental contaminants that adhere on a surface of the thermal barrier coating and form a contaminant composition, said method comprises: depositing a sacrificial oxide coating on the thermal barrier coating in an effective amount so that the oxide coating reacts with the contaminant composition at an operating temperature of the thermal barrier coating by raising a melting temperature or viscosity of the contaminant composition when said contaminant composition forms on the surface of the thermal barrier coating, thereby preventing infiltration of the contaminant composition into the thermal barrier coating.
2. A method according to claim 1 where the thermal barrier coating is a chemically stabilized zirconia selected from the group consisting of yttria- stabilized zirconia, scandia-stabilized zirconia, calcia-stabilized zirconia, and magnesia-stabilized zirconia.
3. A method according to claim 2 where the yttria-stabilized zirconia is about 8 weight percent yttria-92 weight percent zirconia.
4. A method according to claim 1 where the environmental contaminants comprise an oxide selected from the group consisting of magnesium oxide, calcium oxide, aluminum oxide, silicon oxide, iron oxide, nickel oxide and mixtures thereof.
5. A method according to claim 4 where the environmental contaminants form a contaminant composition comprising compositions of calcium- magnesium-aluminum-silicon oxide (CMAS) .
6. A method according to claim 5 where the sacrificial oxide coating is selected from the group consisting of alumina, magnesia, chromia, calcia, calcium zirconate, scandia, silica, magnesium aluminum oxide, and mixtures thereof.
7. A method according to claim 1 where the effective amount of the sacrificial oxide coating increases a melting temperature of the contaminant composition at least about 10°C above a surface temperature of the thermal barrier coating at the operating temperature.
8. A method according to claim 1 where the effective amount of the sacrificial oxide coating increases a viscosity of the contaminant composition so that said contaminant composition does not flow into openings in the thermal barrier coating at the operating temperature of said thermal barrier coating.
9. A method according to claim 1 where the effective amount of the sacrificial oxide coating is about 1-50 weight percent of a weight of the contaminant composition on the surface of the thermal barrier coating.
10. A method according to claim 1 where the sacrificial oxide coating is about 0.2-250 micrometers thick.
11. A method to protect a thermal barrier coating, where a thermal barrier coating comprises about 8 weight % yttria and about 92 weight % zirconia, from degradation by a contaminant composition present on a surface of the thermal barrier coating, where said contaminant composition comprises compositions of calcium-magnesium-aluminum- silicon oxide, said method comprises: depositing an oxide coating selected from the group consisting of alumina, magnesia, chromia, calcia, calcium zirconate, scandia, magnesium aluminum oxide, silica, and mixtures thereof, on the thermal barrier coating in an amount of about at least one weight percent of the contaminant composition present on the surface of the thermal barrier coating to increase a viscosity of the contaminant composition or a melting temperature of said contaminant composition by at least about 10°C above a surface temperature of said thermal barrier coating during operation of the thermal barrier coating.
12. An article comprising a thermal barrier coating on a part with an outer sacrificial oxide coating selected from the group consisting of alumina, magnesia, chromia, calcia, calcium zirconate, scandia, silica, magnesium aluminum oxide, and mixtures thereof, where the sacrificial oxide coating is about 0.2-250 micrometers thick.
13. A method for protecting a thermal barrier coating against damage caused by a liquid composition formed from environmental contaminants at operating temperatures of the thermal barrier coating which comprises forming on a surface of the thermal barrier coating a sacrificial metal oxide coating comprising at least one metal oxide that reacts with said liquid composition and upon contact with said liquid composition raises a melting temperature or viscosity of said liquid composition above a surface temperature of the thermal barrier coating.
14. A method for protecting a thermal barrier coating from damage caused by exposure to a liquid composition comprising oxides of calcium, magnesium, aluminum, and silicon, at operating temperatures of the thermal barrier coating of above about 1000°C which comprises forming on a surface of the thermal barrier coating a sacrificial metal oxide coating comprising at least one metal oxide selected from the group consisting of alumina, magnesia, chromia, calcia, calcium zirconate, scandia, silica, magnesium aluminum oxide, and mixtures thereof, where the sacrificial oxide coating is about 0.2-250 micrometers thick, which upon contact with said liquid composition raises a liquidus of said liquid composition.
15. A composite comprising a thermal barrier coating on a part with a continuous sacrificial oxide coating adjacent to an outer surface of the thermal barrier coating.
16. A composite according to claim 15 where the sacrificial oxide coating is selected from the group consisting of alumina, magnesia, chromia, calcia, calcium zirconate, scandia, silica, magnesium aluminum oxide, and mixtures thereof.
17. A composite according to claim 15 where the sacrificial oxide coating is about 0.2-250 micrometers thick.
18. A composite according to claim 15 where the thermal barrier coating is a chemically stabilized zirconia selected from the group consisting of yttria-stabilized zirconia, scandia-stabilized zirconia, calcia-stabilized zirconia, and magnesia- stabilized zirconia.
19. A composite according to claim 15 where the part is an alloy selected from the group consisting of nickel based alloys, cobalt based alloys, iron based alloys, and mixtures thereof.
20. A protected thermal barrier coated part comprising a part selected from the group consisting of nickel based alloys, cobalt based alloys, iron based alloys, and mixtures thereof, with a thermal barrier coating selected from the group consisting of a chemically stabilized zirconia selected from the group consisting of yttria- stabilized zirconia, scandia-stabilized zirconia, calcia-stabilized zirconia, and magnesia-stabilized zirconia, on said part and a sacrificial oxide coating selected from the group consisting of alumina, magnesia, chromia, calcia, calcium zirconate, scandia, silica, magnesium aluminum oxide, and mixtures thereof, in an amount of about 0.2-250 micrometers thick on an outer surface of said thermal barrier coating.
21. A composite comprising a substrate, a bond coat, a thermal barrier coating, and on the outer surface of the thermal barrier coating a continuous sacrificial oxide coating.
22. An article of manufacture for use in gas turbine engines comprising a part having a surface covered with a thermal barrier coating, where the thermal barrier coating is selected from the group consisting of yttria-stabilized zirconia, scandia- stabilized zirconia, calcia-stabilized zirconia, and magnesia-stabilized zirconia, and said thermal barrier coating having an outer surface covered with a sacrificial oxide coating in an amount of about 0.2- 250 micrometers, where the sacrificial oxide coating is selected from the group consisting of alumina, magnesia, chromia, calcia, calcium zirconate, scandia, silica, magnesium aluminum oxide, and mixtures thereof.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP53031196A JP3995713B2 (en) | 1995-04-03 | 1996-03-18 | Method and composite for protecting a thermal barrier coating with a sacrificial surface coating |
| DE19680223T DE19680223B3 (en) | 1995-04-03 | 1996-03-18 | Method for protecting a thermal barrier coating and corresponding component |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US08/415,913 US5660885A (en) | 1995-04-03 | 1995-04-03 | Protection of thermal barrier coating by a sacrificial surface coating |
| US08/415,913 | 1995-04-03 | ||
| US41757795A | 1995-04-06 | 1995-04-06 | |
| US08/417,577 | 1995-04-06 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO1996031293A1 true WO1996031293A1 (en) | 1996-10-10 |
Family
ID=27023168
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/US1996/003684 WO1996031293A1 (en) | 1995-04-03 | 1996-03-18 | Method and composite for protection of thermal barrier coating by a sacrificial surface coating |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JP3995713B2 (en) |
| KR (1) | KR100436256B1 (en) |
| CH (1) | CH690581A5 (en) |
| DE (1) | DE19680223B3 (en) |
| IN (1) | IN188355B (en) |
| WO (1) | WO1996031293A1 (en) |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1998026110A1 (en) * | 1996-12-10 | 1998-06-18 | Siemens Aktiengesellschaft | Hot-gas exposable product fitted with a heat-insulating layer and a method for the production thereof |
| WO1999023278A1 (en) | 1997-11-03 | 1999-05-14 | Siemens Aktiengesellschaft | Product,especially a gas turbine component, withe a ceramic heat insulating layer |
| EP1382715A1 (en) * | 2002-07-19 | 2004-01-21 | General Electric Company | Protection of a gas turbine component by a vapor-deposited oxide coating |
| WO2010080240A1 (en) * | 2008-12-19 | 2010-07-15 | General Electric Company | Cmas mitigation compositions, environmental barrier coatings comprising the same, and ceramic components comprising the same |
| WO2010080241A1 (en) * | 2008-12-19 | 2010-07-15 | General Electric Company | Methods for making environmental barrier coatings and ceramic components having cmas mitigation capability |
| EP2233600A1 (en) | 2009-03-26 | 2010-09-29 | Alstom Technology Ltd | Method for the protection of a thermal barrier coating system and a method for the renewal of such a protection |
| US7875370B2 (en) | 2006-08-18 | 2011-01-25 | United Technologies Corporation | Thermal barrier coating with a plasma spray top layer |
| US11174557B2 (en) | 2017-01-30 | 2021-11-16 | Siemens Energy Global GmbH & Co. KG | Thermal barrier coating system compatible with overlay |
Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6231998B1 (en) * | 1999-05-04 | 2001-05-15 | Siemens Westinghouse Power Corporation | Thermal barrier coating |
| US7927722B2 (en) * | 2004-07-30 | 2011-04-19 | United Technologies Corporation | Dispersion strengthened rare earth stabilized zirconia |
| US7579087B2 (en) * | 2006-01-10 | 2009-08-25 | United Technologies Corporation | Thermal barrier coating compositions, processes for applying same and articles coated with same |
| EP2128299B1 (en) * | 2008-05-29 | 2016-12-28 | General Electric Technology GmbH | Multilayer thermal barrier coating |
| US8337996B2 (en) * | 2010-11-22 | 2012-12-25 | General Electric Company | Vanadium resistant coating system |
| US11047033B2 (en) | 2012-09-05 | 2021-06-29 | Raytheon Technologies Corporation | Thermal barrier coating for gas turbine engine components |
| US9995169B2 (en) * | 2013-03-13 | 2018-06-12 | General Electric Company | Calcium-magnesium-aluminosilicate resistant coating and process of forming a calcium-magnesium-aluminosilicate resistant coating |
| WO2014184906A1 (en) * | 2013-05-15 | 2014-11-20 | 株式会社日立製作所 | Heat shield coating member |
| DE102014205491A1 (en) * | 2014-03-25 | 2015-10-01 | Siemens Aktiengesellschaft | Ceramic thermal barrier coating system with protective coating against CMAS |
| DE102015221751A1 (en) * | 2015-11-05 | 2017-05-11 | Siemens Aktiengesellschaft | Process for the preparation of a corrosion protection layer for thermal insulation layers of hollow aluminum oxide spheres and outermost glass layer and component and material mixture |
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|---|---|---|---|---|
| US4399199A (en) * | 1979-02-01 | 1983-08-16 | Johnson, Matthey & Co., Limited | Protective layer |
| US5080977A (en) * | 1990-07-31 | 1992-01-14 | United States Of America, As Represented By The Administrator, Nat'l. Aero. And Space Admin. | Composite thermal barrier coating |
| US5223045A (en) * | 1987-08-17 | 1993-06-29 | Barson Corporation | Refractory metal composite coated article |
| US5338577A (en) * | 1993-05-14 | 1994-08-16 | Kemira, Inc. | Metal with ceramic coating and method |
-
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- 1996-03-18 CH CH02952/96A patent/CH690581A5/en not_active IP Right Cessation
- 1996-03-18 JP JP53031196A patent/JP3995713B2/en not_active Expired - Lifetime
- 1996-03-18 DE DE19680223T patent/DE19680223B3/en not_active Expired - Lifetime
- 1996-03-18 WO PCT/US1996/003684 patent/WO1996031293A1/en active Application Filing
- 1996-03-18 KR KR1019960706851A patent/KR100436256B1/en not_active Expired - Lifetime
- 1996-03-26 IN IN543CA1996 patent/IN188355B/en unknown
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4399199A (en) * | 1979-02-01 | 1983-08-16 | Johnson, Matthey & Co., Limited | Protective layer |
| US5223045A (en) * | 1987-08-17 | 1993-06-29 | Barson Corporation | Refractory metal composite coated article |
| US5080977A (en) * | 1990-07-31 | 1992-01-14 | United States Of America, As Represented By The Administrator, Nat'l. Aero. And Space Admin. | Composite thermal barrier coating |
| US5338577A (en) * | 1993-05-14 | 1994-08-16 | Kemira, Inc. | Metal with ceramic coating and method |
Cited By (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1998026110A1 (en) * | 1996-12-10 | 1998-06-18 | Siemens Aktiengesellschaft | Hot-gas exposable product fitted with a heat-insulating layer and a method for the production thereof |
| WO1999023278A1 (en) | 1997-11-03 | 1999-05-14 | Siemens Aktiengesellschaft | Product,especially a gas turbine component, withe a ceramic heat insulating layer |
| EP1382715A1 (en) * | 2002-07-19 | 2004-01-21 | General Electric Company | Protection of a gas turbine component by a vapor-deposited oxide coating |
| US6926928B2 (en) * | 2002-07-19 | 2005-08-09 | General Electric Company | Protection of a gas turbine component by a vapor-deposited oxide coating |
| US7875370B2 (en) | 2006-08-18 | 2011-01-25 | United Technologies Corporation | Thermal barrier coating with a plasma spray top layer |
| US8343589B2 (en) | 2008-12-19 | 2013-01-01 | General Electric Company | Methods for making environmental barrier coatings and ceramic components having CMAS mitigation capability |
| WO2010080241A1 (en) * | 2008-12-19 | 2010-07-15 | General Electric Company | Methods for making environmental barrier coatings and ceramic components having cmas mitigation capability |
| JP2012512966A (en) * | 2008-12-19 | 2012-06-07 | ゼネラル・エレクトリック・カンパニイ | Method for making a ceramic component having environmental barrier coating and CMAS mitigation capabilities |
| WO2010080240A1 (en) * | 2008-12-19 | 2010-07-15 | General Electric Company | Cmas mitigation compositions, environmental barrier coatings comprising the same, and ceramic components comprising the same |
| US8859052B2 (en) | 2008-12-19 | 2014-10-14 | General Electric Company | Methods for making environmental barrier coatings and ceramic components having CMAS mitigation capability |
| EP2233600A1 (en) | 2009-03-26 | 2010-09-29 | Alstom Technology Ltd | Method for the protection of a thermal barrier coating system and a method for the renewal of such a protection |
| US8356482B2 (en) | 2009-03-26 | 2013-01-22 | Alstom Technology Ltd. | Methods for the protection of a thermal barrier coating system and methods for the renewal of such a protection |
| US11174557B2 (en) | 2017-01-30 | 2021-11-16 | Siemens Energy Global GmbH & Co. KG | Thermal barrier coating system compatible with overlay |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3995713B2 (en) | 2007-10-24 |
| DE19680223T1 (en) | 1997-06-05 |
| JPH10502310A (en) | 1998-03-03 |
| DE19680223B3 (en) | 2013-01-17 |
| KR970703205A (en) | 1997-07-03 |
| KR100436256B1 (en) | 2004-07-16 |
| IN188355B (en) | 2002-09-14 |
| CH690581A5 (en) | 2000-10-31 |
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