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WO2005038074A1 - Procede pour appliquer un systeme de revetement a barriere thermique sur un substrat en superalliage - Google Patents

Procede pour appliquer un systeme de revetement a barriere thermique sur un substrat en superalliage Download PDF

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Publication number
WO2005038074A1
WO2005038074A1 PCT/EP2004/052542 EP2004052542W WO2005038074A1 WO 2005038074 A1 WO2005038074 A1 WO 2005038074A1 EP 2004052542 W EP2004052542 W EP 2004052542W WO 2005038074 A1 WO2005038074 A1 WO 2005038074A1
Authority
WO
WIPO (PCT)
Prior art keywords
tbc
heat treatment
component
superalloy
oxidation
Prior art date
Application number
PCT/EP2004/052542
Other languages
English (en)
Inventor
Abdus Suttar Khan
Mohamed Nazmy
Original Assignee
Alstom Technology Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Alstom Technology Ltd filed Critical Alstom Technology Ltd
Publication of WO2005038074A1 publication Critical patent/WO2005038074A1/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • 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
    • 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
    • C23C4/04—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge characterised by the coating material
    • C23C4/10—Oxides, borides, carbides, nitrides or silicides; Mixtures thereof

Definitions

  • the invention relates to a method of applying a thermal barrier coating system 20 to a surface of a component that is made of a superalloy substrate according to the independent claim 1.
  • MCrAIY Ni, Co, or Fe, one or in combination
  • TBC thermal barrier coating
  • MCrAIY protective overlay coatings are widely known in the prior art. They are a family of high temperature coatings. As an example US- A-3,528,861 or US-A-4,585,481 disclose such kind of oxidation resistant coatings. US-A-4, 152,223 as well discloses such method of coating and the coating itself.
  • TBC Thermal-Barrier-Coatings
  • US-A-4,055,705, US-A ,248,940, US-A-4,321,311 or US-A-4,676,994 disclose TBC-coatings for the use in the turbine blades and vanes.
  • the ceramics used are yttria-stabilized zirconia (YSZ). This material is applied by plasma spraying (US-A-4,055,705, US-A-4,248,940) or by an electron beam process (US-A-4,321 ,311, US-A-4,676,994) wherein the yttria stabilized zirconia is applied on top of the MCrAIY bond coat.
  • the plasma sprayed TBCs generally fail by delamination and a number of factors are thought to contribute to the failure of the TBC:
  • the first approach has been to stress relief of TBC i.e. make the TBC more strain tolerant by optimization of process parameters producing a strain tolerant microstructure.
  • the second approach is to promote formation of a pure and continuous alumina scale containing no or negligible mixed oxides.
  • segmented TBC Vertical segmentation of TBC by depositing dense TBC (US 5,073,433), using a Praxair gun provided an alternative mechanism of stress relief of TBC.
  • segmented TBC are described in US-B 1-6,224,963 where a segmented TBC is produced by a laser drilling of a selected area of a TBC.
  • US-A-5,681 ,616 describes segmented TBC by abrading a portion of the TBC with a high-pressure liquid jet.
  • segmented TBC is described in US 5,840,434 wherein a segmented TBC is produced by control of EBPVD process parameters.
  • a method of forming a macro-segmented TBC by placing a three- dimensional pattern or feature on the surface is disclosed in US-A- 6,316,078.
  • the disclosed features could be either raised ribs or grooves on the substrate or on the bond coat.
  • a surface is formed by a cast feature or rivets placed on the surface upon which the TBC is deposited, d)
  • a different method to stress relief TBC is described in US-A-4,457,948 where a stress relief in TBC is provided by a post-coating heat-treatment by rapid quenching of TBC samples from elevated temperature which resulted in a cracking of the TBC .
  • the other approach of improving the durability of TBC is to minimize expansion mismatch or promote a formation of pure alumina TGO with no mixed oxides. The technology is summarized here:
  • the first formed oxide in here will contain NiO, CoO, Cr 2 ⁇ 3 and spinel, besides, alumina.
  • the amount of non-protective oxides in TGO becomes high.
  • the oxides in TGO remain in place and continue grow until the TBC is let go.
  • Practical approaches to form continuous alumina only TGO have been difficult.
  • the oxidation of superalloys is poor and they are unable to sus- tain alumina growth with time and temperature. Due to limitation of the oxidation resistance of superalloy the industry is forced to use the bond coats (i.e. MCrAIY) with the TBC system with the full knowledge of its shortcoming.
  • a durable TBC is described in US 5,262,245 by first forming a thin alumina scale upon the superalloy substrate directly in a chamber prior to TBC deposition.
  • the TBC has a columnar grain structure deposited by EBPVD. The pre-oxidation was done by leaking oxygen in a controlled rate in the deposition chamber while the specimens were being heated by diffused electron beam. Subsequently TBC was deposited by vaporizing the target using focus beam. The alumina thickness was in the range 0.25 to 20 microns. The resulting columnar grain TBC had higher durability.
  • the superalloy must have the ability to form adherent alumina scale
  • Pre-treatment of a superalloy substrate to remove sulfur from the superalloy substrate Sulfur is known to adversely affect oxidation of superalloy. The sulfur free superalloy upon oxidation forms alumina scale.
  • sulfur is removed from a superalloy by using magnesium salts at elevated temperature (US 5,346,563).
  • Magnesium interacts with the existing scale and makes the scale porous to sulfur thus allowing sulfur to escape to the environment. Removal of sulfur allows formation of pure alumina scale upon which the columnar grain TBC is deposited by EBPVD process.
  • sulfur is removed from a superalloy by flowing pure hydrogen over the superalloy at elevated temperature (US 5,538,796).
  • the substrate subsequently oxidized formed alumina scale upon which columnar grain TBC was deposited by EBPVD process.
  • a portion of the substrate Prior to alumina formation a portion of the substrate can be coated optionally with alumina or an environmental coating that form an alumina scale upon oxidation.
  • a durable TBC without a bond coat is deposited by plasma spraying process.
  • the method of applying a coating system to the surface of a component made of a superalloy substrate which is capable to form alumina scale comprises the steps of
  • the advantage of the invention is that the process is simple and that TBC can be deposited by thermal spraying without a bond coat.
  • the new method does not require complex purification steps prior to TBC deposition. There is no need for applying a bond coat to the surface of the substrate prior to the applying of the TBC.
  • the plasma spray TBC has lower thermal con- ductivity and therefore is preferred. Additionally, the plasma spray process is adaptable to large industrial gas turbine components.
  • the heat treatment is carried out in air or in an atmosphere with reduced oxygen partial pressure.
  • the heat treatment temperature and time can be adjusted based upon super- alloy oxidation behavior at elevated temperature.
  • the heat treatment temperature and time are determined by the superalloy oxidation characteristics and the heat treatment temperature is in the range up to 1200°C for a period up to 100 hours in air or an gaseous atmosphere with reduced oxygen partial pressure. Often some superalloy substrate may require the above conditions to promote pure alumina scale. Reduced pressure may also be advantageous for the stated reasons.
  • the oxygen partial pressure in the environment is controlled at a temperature and time suitable to form a continuous and adherent alumina scale. This allows a good adhesion of the TBC without a bond coat.
  • the layer thickness of the scale formed after the second heat treatment is at least 50 nanometer.
  • the ceramic coating that is applied with a plasma spray process to that scale has a thickness in a range of up to 3 mm and a porosity of 10 to 25 %.
  • the superalloy substrate can be a nickel base, cobalt base or iron base alloy.
  • Fig. 1 shows a gas turbine blade
  • Fig. 2 shows a micrograph of the surface (the initial state) of two samples applied with a coating system according to the invention
  • Fig. 3 shows a micrograph of the surface (after isothermal and cyclic tests) of the two samples in Fig. 2.
  • the present invention is generally applicable to components that operate within environments characterized by relatively high temperature, and are therefore subjected to severe thermal stresses and thermal cycling.
  • Notable examples of such components include the high and low-pressure vanes and blades, shrouds, liners for combustion chambers and augmentor hardware of gas turbine engines.
  • Fig. 1 shows as an example such a component 1 comprising a blade 2 against which hot combustion gases are directed during operation of the gas turbine engine.
  • the blade 2 has cooling holes 4, which are on the external surface 5 of the component 1 as well as on the platform 3 of the component. Through the cooling holes 4 cooling air is ducted during operation of the engine to cool the surface 5.
  • the surface 5 is subjected to severe attack by oxidation, corrosion and erosion due to the hot combustion gases.
  • the component 1 consists of a nickel, a cobalt, or an iron base superalloy.
  • the component 1 can be single crystal (SX), directionally solidified (DS) or polycrystalline. While the advantages of this invention are described with reference to a turbine blade or vane as shown in Fig.
  • the invention is generally applicable to any component on which a coating system 6 - ceramic thermal barrier coating (TBC) - may be used to protect the component from its environment.
  • TBC thermal barrier coating
  • the blade 2 in this embodiment of the invention is made of a nickel base super- alloy with the following chemical composition (in weight %): 0.02 C 0.13 Si 5.0 Al 0.005 B 5.0 Co
  • This superalloy has an excellent oxidation behaviour in forming adherent AI 2 O3 to deposit ceramic TBC by plasma spraying directly on the surface of the article without using a bond coat.
  • Plasma sprayed TBC is the most suitable coating for industrial gas turbine engine due to its low thermal conductivity and low costs.
  • the surface roughness is optimised by grit blasting to promote pure alumina TGO (thermally grown oxides) and TBC microstructure with optimum porosity.
  • the method of applying a coating system 6 to the surface 5 of the blade 2 comprises the following steps in this embodiment of the invention: - first grit blasting of the surface 5 of the blade 2 followed by a heat treatment of the blade 2 in air at elevated temperature for pre-oxidation of the surface 5, cooling of the blade 2, and - repeated grit blasting of the surface 5 of the blade 2 followed by a heat treatment in air at elevated temperature, cooling, and then - depositing a ceramic TBC (thermal barrier coating) 6 on top of said heat- treated substrate by air plasma spraying.
  • the first grit-blasting step is necessary to induce an optimum surface roughness that should be in the range from 20 to 50 micrometer. Then follows the first heat treatment in air at 1050 - 1080 "C/1-4 h.
  • the present example is heat treated in air at 1080 °C/4 h. This leads to a pre-oxidation of the surface 5.
  • the formed oxides are Al 0 3 , which unfortunately do also contain NiO/Cr 2 0 3 .This is a disadvantage because non-pure Al 2 0 3 does not allow a good adhesion of the TBC 6. Therefore a second grit-blasting step is necessary to remove the formed AI 2 O3 with NiO/Cr 2 0 3 .
  • the grit-blasting process uses such time and media that are able to remove the first formed alumina scale. Cr (in the ⁇ -phase) is enriched in the scale layer during the first heat treatment. Therefore the Cr concentration in the layers below the scale layer is lowered.
  • the second grit-blasting process is followed by a second heat treatment at 1080°C/4h in an inert gaseous atmosphere with reduced oxygen partial pressure.
  • the only difference between the second and the first example of the invention is the reduced oxygen partial pressure in the second teat treatment which should be less than 10 ⁇ 4 atm. Under reduced oxygen pressure NiO is completely unstable, therefore the formation of AI2O3 only is promoted.
  • the next step is applying a ceramic TBC 6 with the well-known air plasma spray (APS) process directly to the surface 5 of the oxidized substrate.
  • the used TBC is 7% yttria stabilized zirconia (Zr0 2 stabilized with Y 2 0 3 ). It has a porosity of 10-25 % and a thickness of about 250-350 ⁇ m.
  • the last step is an ageing at 870 °C for 16 h, which is needed for the base alloy.
  • the coating system applied with a method according to the invention has excel- lent properties with respect to the resistance against damages or spallation.
  • Fig. 2 shows a micrograph of the initial state of two samples of the above- described Nickel base superalloy component with TBC without a bond coat.
  • Fig. 3 shows a micrograph of the same samples after the cyclic and isothermal tests.
  • the upper sample was tested at 1000 °C/1000 h/ air cooling
  • This experiment tests the effect of cumulative TGO built up followed by cooling to room temperature. The sample survived more than 1000 hours isothermal exposure followed air cooling to room temperature without damage or spallation of TBC.
  • the lower sample in Fig. 3 shows the result of a cyclic test at 1000 °C/1 h followed by 10 minutes cooling to room temperature (air cooling). The test simulates the effect of thermal shock on TBC adhesion. The sample survived 100 cycles at 1000 °C without showing any TBC damage or spallation.
  • the invention is not limited to the above-described embodiment.
  • different superalloys can be used, such as cobalt base or iron base alloys.
  • the treatment temperature and time can be adjusted based upon superalloy oxidation behavior at elevated temperature.
  • the temperature and time are determined by the superalloy oxidation characteristics and the heat treatment temperature can be in the range up to 1200°C for a period up to 100 hours in air or reduced oxygen partial pressure.
  • the heat treatment can be carried out in reducing atmosphere to control oxygen partial pressure in the environment at a temperature and time suitable to form a continuous and adherent alumina scale.

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

Abstract

La présente invention concerne un procédé pour déposer un revêtement à barrière thermique (thermal barrier coating / TBC) projeté par plasma, sans couche d'accrochage. Le procédé comprend les étapes suivantes: traitement de surface par grenaillage suivi du traitement thermique dans l'air ou dans une atmosphère à pression partielle d'oxygène réduite; puis second grenaillage suivi d'un traitement thermique, le TBC étant ensuite déposé par pulvérisation par plasma dans l'air. Le revêtement résiste à la spallation au cours de cycles thermiques, et au refroidissement rapide qui suit une exposition isotherme à long terme.
PCT/EP2004/052542 2003-10-17 2004-10-14 Procede pour appliquer un systeme de revetement a barriere thermique sur un substrat en superalliage WO2005038074A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP03103862.3 2003-10-17
EP03103862 2003-10-17

Publications (1)

Publication Number Publication Date
WO2005038074A1 true WO2005038074A1 (fr) 2005-04-28

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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102005050873A1 (de) * 2005-10-21 2007-04-26 Rolls-Royce Deutschland Ltd & Co Kg Verfahren zur Herstellung einer segmentierten Beschichtung und nach dem Verfahren hergestelltes Bauteil
US8726973B2 (en) 2010-01-26 2014-05-20 Rolls-Royce Plc Method of producing an integral self supporting coating test piece from a coating material
US9151175B2 (en) 2014-02-25 2015-10-06 Siemens Aktiengesellschaft Turbine abradable layer with progressive wear zone multi level ridge arrays
US9243511B2 (en) 2014-02-25 2016-01-26 Siemens Aktiengesellschaft Turbine abradable layer with zig zag groove pattern
US10189082B2 (en) 2014-02-25 2019-01-29 Siemens Aktiengesellschaft Turbine shroud with abradable layer having dimpled forward zone
US10190435B2 (en) 2015-02-18 2019-01-29 Siemens Aktiengesellschaft Turbine shroud with abradable layer having ridges with holes
US10323533B2 (en) 2014-02-25 2019-06-18 Siemens Aktiengesellschaft Turbine component thermal barrier coating with depth-varying material properties
US10408079B2 (en) 2015-02-18 2019-09-10 Siemens Aktiengesellschaft Forming cooling passages in thermal barrier coated, combustion turbine superalloy components
WO2020180325A1 (fr) * 2019-03-07 2020-09-10 Oerlikon Metco (Us) Inc. Matériaux de couche d'accrochage avancés pour des tbc présentant une résistance améliorée à la fatigue sous des variations cycliques de température et à la sulfuration

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5262245A (en) * 1988-08-12 1993-11-16 United Technologies Corporation Advanced thermal barrier coated superalloy components
US5302465A (en) * 1992-10-26 1994-04-12 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Plasma sprayed ceramic thermal barrier coating for NiAl-based intermetallic alloys
US5538796A (en) * 1992-10-13 1996-07-23 General Electric Company Thermal barrier coating system having no bond coat

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5262245A (en) * 1988-08-12 1993-11-16 United Technologies Corporation Advanced thermal barrier coated superalloy components
US5538796A (en) * 1992-10-13 1996-07-23 General Electric Company Thermal barrier coating system having no bond coat
US5302465A (en) * 1992-10-26 1994-04-12 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Plasma sprayed ceramic thermal barrier coating for NiAl-based intermetallic alloys

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102005050873A1 (de) * 2005-10-21 2007-04-26 Rolls-Royce Deutschland Ltd & Co Kg Verfahren zur Herstellung einer segmentierten Beschichtung und nach dem Verfahren hergestelltes Bauteil
DE102005050873B4 (de) * 2005-10-21 2020-08-06 Rolls-Royce Deutschland Ltd & Co Kg Verfahren zur Herstellung einer segmentierten Beschichtung und nach dem Verfahren hergestelltes Bauteil
US8726973B2 (en) 2010-01-26 2014-05-20 Rolls-Royce Plc Method of producing an integral self supporting coating test piece from a coating material
US9151175B2 (en) 2014-02-25 2015-10-06 Siemens Aktiengesellschaft Turbine abradable layer with progressive wear zone multi level ridge arrays
US9243511B2 (en) 2014-02-25 2016-01-26 Siemens Aktiengesellschaft Turbine abradable layer with zig zag groove pattern
US9920646B2 (en) 2014-02-25 2018-03-20 Siemens Aktiengesellschaft Turbine abradable layer with compound angle, asymmetric surface area ridge and groove pattern
US10189082B2 (en) 2014-02-25 2019-01-29 Siemens Aktiengesellschaft Turbine shroud with abradable layer having dimpled forward zone
US10221716B2 (en) 2014-02-25 2019-03-05 Siemens Aktiengesellschaft Turbine abradable layer with inclined angle surface ridge or groove pattern
US10323533B2 (en) 2014-02-25 2019-06-18 Siemens Aktiengesellschaft Turbine component thermal barrier coating with depth-varying material properties
US10190435B2 (en) 2015-02-18 2019-01-29 Siemens Aktiengesellschaft Turbine shroud with abradable layer having ridges with holes
US10408079B2 (en) 2015-02-18 2019-09-10 Siemens Aktiengesellschaft Forming cooling passages in thermal barrier coated, combustion turbine superalloy components
WO2020180325A1 (fr) * 2019-03-07 2020-09-10 Oerlikon Metco (Us) Inc. Matériaux de couche d'accrochage avancés pour des tbc présentant une résistance améliorée à la fatigue sous des variations cycliques de température et à la sulfuration

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