WO2022189033A1 - Strain-tolerant thermal barrier coatings by arc evaporation with improved cmas resistance - Google Patents
Strain-tolerant thermal barrier coatings by arc evaporation with improved cmas resistance Download PDFInfo
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- WO2022189033A1 WO2022189033A1 PCT/EP2022/000022 EP2022000022W WO2022189033A1 WO 2022189033 A1 WO2022189033 A1 WO 2022189033A1 EP 2022000022 W EP2022000022 W EP 2022000022W WO 2022189033 A1 WO2022189033 A1 WO 2022189033A1
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- strain
- tolerant
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- oxide
- substrate
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- 239000012720 thermal barrier coating Substances 0.000 title claims description 16
- 230000008020 evaporation Effects 0.000 title description 20
- 238000001704 evaporation Methods 0.000 title description 20
- 238000000576 coating method Methods 0.000 claims abstract description 45
- 239000011248 coating agent Substances 0.000 claims abstract description 41
- 238000000034 method Methods 0.000 claims abstract description 21
- 239000000758 substrate Substances 0.000 claims abstract description 12
- 238000000541 cathodic arc deposition Methods 0.000 claims abstract description 10
- 239000000463 material Substances 0.000 claims abstract description 10
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 claims abstract description 7
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 claims abstract description 6
- 229910052726 zirconium Inorganic materials 0.000 claims abstract description 6
- 229910052729 chemical element Inorganic materials 0.000 claims abstract 3
- 239000010987 cubic zirconia Substances 0.000 claims abstract 2
- 229910052688 Gadolinium Inorganic materials 0.000 claims description 8
- 230000007704 transition Effects 0.000 claims description 5
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 4
- 229910052772 Samarium Inorganic materials 0.000 claims description 3
- 229910052769 Ytterbium Inorganic materials 0.000 claims description 3
- 229910052727 yttrium Inorganic materials 0.000 claims description 3
- 230000000087 stabilizing effect Effects 0.000 claims 3
- 238000000151 deposition Methods 0.000 description 11
- 230000008021 deposition Effects 0.000 description 11
- 230000008569 process Effects 0.000 description 11
- 229910001233 yttria-stabilized zirconia Inorganic materials 0.000 description 9
- 239000007789 gas Substances 0.000 description 8
- 238000005328 electron beam physical vapour deposition Methods 0.000 description 7
- 238000010438 heat treatment Methods 0.000 description 5
- 229910052761 rare earth metal Inorganic materials 0.000 description 5
- 239000013077 target material Substances 0.000 description 5
- 238000005137 deposition process Methods 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 238000001816 cooling Methods 0.000 description 3
- 238000010891 electric arc Methods 0.000 description 3
- UIWYJDYFSGRHKR-UHFFFAOYSA-N gadolinium atom Chemical compound [Gd] UIWYJDYFSGRHKR-UHFFFAOYSA-N 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- 238000005240 physical vapour deposition Methods 0.000 description 3
- 150000002910 rare earth metals Chemical class 0.000 description 3
- 229910002076 stabilized zirconia Inorganic materials 0.000 description 3
- 150000001875 compounds Chemical class 0.000 description 2
- 238000003786 synthesis reaction Methods 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 238000005524 ceramic coating Methods 0.000 description 1
- 239000012700 ceramic precursor Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- KZHJGOXRZJKJNY-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Si]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O KZHJGOXRZJKJNY-UHFFFAOYSA-N 0.000 description 1
- 239000002019 doping agent Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 150000002484 inorganic compounds Chemical class 0.000 description 1
- 229910010272 inorganic material Inorganic materials 0.000 description 1
- 238000000626 liquid-phase infiltration Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 150000001247 metal acetylides Chemical class 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 230000000116 mitigating effect Effects 0.000 description 1
- 229910052863 mullite Inorganic materials 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- 238000007750 plasma spraying Methods 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 230000003252 repetitive effect Effects 0.000 description 1
- 238000001878 scanning electron micrograph Methods 0.000 description 1
- 229910021332 silicide Inorganic materials 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000007751 thermal spraying Methods 0.000 description 1
- 229910052723 transition metal Inorganic materials 0.000 description 1
- UONOETXJSWQNOL-UHFFFAOYSA-N tungsten carbide Chemical compound [W+]#[C-] UONOETXJSWQNOL-UHFFFAOYSA-N 0.000 description 1
- 238000013022 venting Methods 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- 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
- C23C14/32—Vacuum evaporation by explosion; by evaporation and subsequent ionisation of the vapours, e.g. ion-plating
- C23C14/325—Electric arc evaporation
-
- 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
- C23C14/0021—Reactive sputtering or evaporation
-
- 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
-
- 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
- F05D2230/00—Manufacture
- F05D2230/30—Manufacture with deposition of material
- F05D2230/31—Layer deposition
- F05D2230/313—Layer deposition by physical vapour deposition
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
- F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
- F05D2230/00—Manufacture
- F05D2230/90—Coating; Surface treatment
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
- F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
- F05D2300/00—Materials; Properties thereof
- F05D2300/20—Oxide or non-oxide ceramics
- F05D2300/21—Oxide ceramics
- F05D2300/2118—Zirconium oxides
-
- 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
- F05D2300/60—Properties or characteristics given to material by treatment or manufacturing
- F05D2300/605—Crystalline
-
- 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
- F05D2300/60—Properties or characteristics given to material by treatment or manufacturing
- F05D2300/611—Coating
Definitions
- Figure 5 shows an SEM image of the columnar structure of a stand-alone strain- tolerant oxide coating with a Gd content of 15 at.% Gd on the metal sublattice.
Abstract
The present invention relates to a method for applying a strain tolerant oxide coating on a substrate, the strain-tolerant oxide comprising zirconia or zirconate as main component, characterized in that the strain tolerant oxide is applied by cathodic arc deposition using at least one zirconium target as material source the zirconium target in addition comprising at least one chemical element that stabilizes cubic zirconia.
Description
Strain-tolerant thermal barrier coatings by arc evaporation with improved CMAS resistance To increase the operation temperature of stationary and aviation gas turbines an intricate cooling system for turbine blades is required. This is usually realized by internal cooling channels, cooling holes to generate a film of cool gas at the blade surface and thermal barrier coatings (TBC) with low thermal conductivity to maximize the temperature gradient from the coating surface to the coating-to-blade interface.
Conventional thermal barrier coatings consist of a bondcoat layer to ensure good adhesion of the TBC to the substrate, a thermally grown oxide (TGO) layer and a strain- tolerant oxide layer (STO). The STO usually is a porous structure and exhibits a columnar or cracked morphology in order to compensate the thermal expansion of the blade and reduce the thermal conductivity.
Conventional STOs are based on Yttria-stabilized Zirconia (YSZ). Two particular nonlimiting compositions with commercial use are 7wt% yttria stabilized zirconia (7YSZ) or 8wt% yttria stabilized zirconia (8YSZ) due to their high toughness and their low thermal conductivity up to high temperatures. Thermal barrier coatings are usually deposited by atmospheric plasma spraying (APS) or electron beam physical vapor deposition (EB-PVD). For the STO layer, APS utilizing dedicated conditions, delivers a dense vertically or horizontally cracked structure. EB- PVD delivers a columnar structure that is superior in sustaining the significant miss- match of thermal expansion between the metallic blade and the ceramic coating. This columnar structure of the STO therefore is favored for aero engine applications despite the high production costs for these types of coatings.
To increase the efficiency of the turbine, engine operating temperatures were increased over the last decade. For these temperatures, molten siliceous deposits generically known as CMAS (calcium-magnesium-alumino-silicate) attack the YSZ- based TBCs. They have been recognized as a critical factor affecting TBCs durability, and they are a fundamental barrier to progress in gas turbine technology. Various mitigation strategies to the problem of CMAS degradation have been attempted. The, up to now, most promising strategy seeks to increase the reactivity between the coating
and the CMAS melt. These reactions consume the melt while the crystalline reaction products form a dense layer and block the paths for further melt infiltration. Most of these CMAS reactive TBCs are based on rare earth zirconates, whereas the commonly-used rare earth elements are: Gd, Yb, Sm. However compositions with these elements typically have a lower toughness than the YSZ coatings.
Typically, TBCs require a bondcoat based on PtAI or MCrAIX which usually is deposited by thermal spraying or EB-PVD in a separate process. It is very common, that it is necessary to roughen the surface of the blades before coating in order to achieve good adhesion. Especially in case of thermally sprayed bondcoats, often a surface finishing is required after deposition of the bondcoat to facilitate the low roughness required for the subsequent STO deposition. In addition, many of these bondcoats do require a heat treatment to achieve the necessary properties, as well as a thermally grown oxide (TGO) layer on top to ensure good adhesion of the TBC itself
Conventional YSZ STOs are very reactive with CMAS compounds and get degraded, leading to a loss of their strain resistance and further on functionality.
Both processes, APS and EB-PVD, require a very defined surface quality to achieve good coating adhesion.
Both processes, APS and EB-PVD, utilize ceramic precursors with high melting temperature. This makes the processes very energy-consuming and expensive.
There is therefore a need for a deposition process which is less energy consuming, less expensive and which prerequisites less defined surface quality.
It is therefore an objective of the present invention to disclose a deposition process which is less energy consuming, less expensive and which prerequisites less defined surface quality.
According to the present invention, the coating systems as described are coated by cathodic arc evaporation.
Cathodic arc evaporation (CAE) is a known physical vapor deposition process. An arc evaporator usually comprises a target material operable as cathode during an arc evaporation. The arc evaporator is placed in a vacuum chamber of a coating apparatus. The arc evaporator may also comprise at least one electrode operable as anode during arc evaporation. For the execution of a cathodic arc evaporation process usually means are used for igniting a high current discharge, establishing a plasma and forming an arc with a spot moving across the surface of the target, thereby tearing electrons out of the target surface. The heat created at the spot causes target material to be evaporated. Therefore, the arc evaporator is as well named coating source or plasma source. The terms “evaporator” and “coating source" and “plasma source” are used as equivalent terms throughout this description. The CAE process is performed in vacuum environment. However, the process can be supported by working gases which can stabilize the arc discharge. In addition to this, reactive gases can be fed to the vacuum and added to the arc discharge. The intense plasma of the arc discharge dissociates and excites the specific reactive gases and incorporates them to the synthesized coating. In this way it is possible to synthesize not only metallic coatings, but also oxides, carbides, borides, silicides and more complex coating materials.
With the use of cathodic arc evaporation the synthesis of the STO, utilizing metallic evaporation material, can be facilitated at lower cost and greater robustness as compared to APS and/or EB-PVD. In addition, compared to EB-PVD or APS, the evaporation rates of materials and the target surface composition (due to a repetitive melting-quenching-process of arc evaporation) are not or only little affected by the significant difference in melting- and boiling point between the rare earth element and zirconium. This allows to deposit a coating of homogenous chemical composition.
The synthesis of the oxide compound is achieved by performing the CAE as a reactive PVD process in which for example transition metal elements are evaporated from the target surface and react with the oxygen which is introduced into the coating chamber as reactive gas to form a ceramic oxide coating on the substrate surface.
By tuning the deposition pressure and the evaporation rate, the re-nucleation behavior of the growing coating can be manipulated and the coating morphology can be adjusted from an amorphous and/or nanocrystalline and/or micro-crystalline
morphology to a columnar structure that is desired in STOs. Typical ranges in the evaporation rate (per target) for the target materials are between 0.5 g/h and 100 g/h for an oxygen partial pressure in the vacuum chamber between 0.1 Pa and 10 Pa. Because the evaporation rates in arc evaporation are controlled by the arc current, the range normalized to typical arc currents covers the range between 0.0025 g/h/A (assuming 200 A arc current) to 1 g/h/A (assuming 100 A arc current).
Microcrystalline morphology, as used in this description, shall mean a morphology where the material/layer comprises a high percentage of crystallites with a size in the order of magnitude of 100 nm to several microns.
Nanocrystalline morphology as used in this description shall mean a morphology where the material/layer comprises a high percentage of crystallites with a size in the order of magnitude of one or several nanometers.
Due to the flexibility of the deposition process with respect to metallic materials to be evaporated, the deposition is not limited to YSZ material. This allows to deposit materials that are more resistant to CMAS atack such as rare-earth zirconates (e.g. pyrochlore-structured Gadolinium Zirconate) or alumina-based STO layers, like Mullite with specific dopants.
By using CAE the whole coating system (= layer stack) can be deposited in a deposition process which is not interrupted, i.e. for which the substrates to be coated with the TBC are not exposed to ambient before the TBC is completed. This means the time consuming evacuation and heating of the coating chamber has to be performed just once. Even more important is the reliability which can be achieved under vacuum conditions. In such a single process the bond-coat material is deposited from for example one group of coating sources (non-limiting example e.g. CoNiCrAIY target material), while the STO is deposited from a second group of plasma sources (e.g. from Zr-Y or Zr-Y-Gd or Zr-Gd targets).
Heat treatment as well as the formation of a thermally grown oxide can be realized in the same coating chamber without venting and opening it in between. However, a final heating or annealing step in controlled ambient or vacuum conditions of the completed in-situ produced TBC layer stack may still improve the quality. However, due to the
high-energetic, dense and homogeneous growth mechanism of CAE, for many applications the heat treatment will not be required.
The coating can be deposited with a gradient structure of columnar growth at the bottom for strain-resistance and increasing density for reduced penetrability against molten inorganic compounds. Usually this is realized by adjusting the ratio of the metal vapor from the arc sources and the corresponding gas flow fed to the chamber.
The TGO can be replaced by deposition of a thin CAE oxide layer (alumina, alumina- based oxides) from a metallic target material with a third group of plasma sources.
CMAS-resistant overlay coatings (like alumina-based oxides, Gadolinium Zirconate or other rare-earth containing oxides) can be deposited in the same process from a fourth group of coating sources as well.
The invention will now be described on the basis of an example, which is enabling but not limiting to the scope of the invention. And the invention will be described with the help of the figures 1 to 6. Figure 1 a schematically shows a STO directly deposited on a substrate, the STO being realized with cathodic arc deposition.
Figure 1b schematically shows a STO deposited on a bondcoat layer, the STO being realized with cathodic arc deposition.
Figure 1c schematically shows a STO deposited on a thermally grown oxide layer on a bondcoat, the STO being realized with cathodic arc deposition.
Figure 2a schematically shows a STO deposited on a bondcoat layer, the STO as well as the bondcoat layer being realized with cathodic arc deposition, the STO having columnar structure.
Figure 2b schematically shows a STO deposited on a thermally grown oxide layer which is on a bondcoat layer, the STO as well as the boadcoat layer being realized with cathodic arc deposition, the STO having columnar structure. Figure 2c schematically shows a STO deposited on an oxide layer which is on a bondcoat layer, the STO, boadcoat layer and deposited oxide layer being realized with cathodic arc deposition, the STO having columnar structure.
Figures 3a, 3b and 3c show the same as figures 1a, 1b and 1c respectively, however on top of the columnar STO there is a nano- or micro-crystalline STO realized e.g. by cathodic arc evaporation, preferably with gradient transition from columnar to microcrystalline.
Figures 4a, 4b and 4c show the same as figures 2a, 2b and 2c respectively, however on top of the columnar STO there is a nano- or micro-crystalline STO realized e.g. by cathodic arc evaporation, preferably with gradient transition from columnar to microcrystalline.
Figure 5 shows an SEM image of the columnar structure of a stand-alone strain- tolerant oxide coating with a Gd content of 15 at.% Gd on the metal sublattice.
Figure 6: XRD spectrum of the coating from Figure 5 deposited on a tungsten carbide substrate (substrate peaks are marked). The peaks of the coating correspond with cubic Gd-stabilized Zirconia in the reference given below (Basi et al.).
As example, a zirconium target comprising as well 15 at.% gadolinium as element is used for the cathodic arc evaporation. In order to run the arc evaporation a power density of 23W/cm2 was applied to the target used as cathode with an evaporation rate of 22 g/h and an oxygen flow of 485 seem O2 was utilized.
The coating created thereby turned out to be a Gd stabilized zirconia, with a Gd content of about 15 at.% on the metal sub-lattice. The XRD measurements in Figure 6 indicate in good agreement with the reference (Basu, Sohini & Varma, Salil & Shirsat, A. & Wani, B.N. & Bharadwaj, Saurav & Chakrabarti, Aparna & Jha, S.N. & Bhattacharyya,
D.. (2013). Extended X-ray Absorption Fine Structure (EXAFS) Study of Gd doped Zr02 systems. Journal of Applied Physics. 113. 043508. 10.1063/1.4788823) that the coating has a cubic structure. According to one deposition run a micro-crystalline morphology was achieved by adjusting the deposition pressure to around 1 Pa. According another deposition run a columnar structure was achieved by adjusting the deposition pressure to 2 Pa. Higher pressures like 4 Pa lead as well to a columnar structure as demonstrated in Figure 5. Figure 5 shows a stand-alone Gd-stabilized Zirconia coating with a Gd content of 15 at.% on the metal sub-lattice and a columnar structure. This indicates that the metallic content in the target determines approximately the metallic content in the synthesized coating.
In order to achieve a transition from columnar structure to micro-crystalUne morphology as schematically shown in figure 3a, the coating is started with a deposition pressure of 2 Pa or higher. After a predetermined period of time (in particular after deposition of a certain coating thickness), the coating pressure is slowly decreased below 2 Pa down to 1 Pa, which leads to a transition from columnar structure to nano- or micro-crystalline morphology.
Claims
1. Method for applying a strain tolerant oxide coating on a substrate, the strain-tolerant oxide comprising zirconia or zirconate as main component, characterized in that the strain tolerant oxide is applied by cathodic arc deposition using at least one zirconium target as material source the zirconium target in addition comprising at least one chemical element that stabilizes cubic Zirconia.
2. Method according to claim 1, characterized in that the at least one stabilizing chemical element is one or more elements selected from the group formed by: Y, Gd, Yb, Sm.
3. Method according to one of claims 1 and 2, characterized in that the method comprises a step to apply a bondcoat layer between the substrate and the strain- tolerant oxide coating, the bondcoat layer preferably being applied by means of cathodic arc deposition.
4. Method according to one of the previous claims, characterized on that the method comprises a step of realizing an oxide layer based on Alumina between the substrate and the strain tolerant oxide layer, the oxide layer preferably being realized by thermal growing and/or cathodic arc deposition.
5. Method according to one of the previous claims, characterized in that at least the first part of the strain-tolerant oxide is coated in such a manner that a columnar structure is realized.
6. Method according to claim 5, characterized in that after coating of the first part at least a second part of the strain-tolerant oxide coating is coated in such a manner that an amorphous and/or nanocrystalline and/or microcrystalline morphology is realized.
7. Strain-tolerant oxide coating on a substrate, where the strain-tolerant oxide coating comprises a zirconia layer with stabilizing elements, characterized in that the stabilizing elements are one or more elements from the group formed by Y, Gd, Yb, Sm.
8. Strain-tolerant oxide coating according to claim 7, characterized in that the thermal barrier coating comprises a first part and a second part, the first part being closer to the substrate as the second part, characterized in that the first part has columnar structure and the second part has amorphous and/or nanocrystalline and/or microcrystalline structure.
9. Strain-tolerant oxide coating according to claim 7 or 8, characterized in that the strain-tolerant oxide coating comprises a gradient in morphology leading to a transition form columnar structure to amorphous and/or nanocrystalline and/or microcrystalline structure.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE102021001249.6 | 2021-03-09 | ||
| DE102021001249 | 2021-03-09 |
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| Publication Number | Publication Date |
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| WO2022189033A1 true WO2022189033A1 (en) | 2022-09-15 |
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| PCT/EP2022/000022 WO2022189033A1 (en) | 2021-03-09 | 2022-03-07 | Strain-tolerant thermal barrier coatings by arc evaporation with improved cmas resistance |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101307424A (en) * | 2007-05-16 | 2008-11-19 | 中国科学院金属研究所 | Process for preparing zirconia coating |
| US20100159261A1 (en) * | 2008-12-19 | 2010-06-24 | Glen Harold Kirby | Environmental barrier coatings providing cmas mitigation capability for ceramic substrate components |
| US20180290929A1 (en) * | 2017-04-07 | 2018-10-11 | General Electric Company | Thermal Barrier System with Thin Dense Columnar TBC Layer and Methods of Forming the Same |
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2022
- 2022-03-07 WO PCT/EP2022/000022 patent/WO2022189033A1/en active Application Filing
Patent Citations (3)
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