EP0185603B1 - Improved durability metallic-ceramic turbine air seals - Google Patents

Improved durability metallic-ceramic turbine air seals Download PDF

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Publication number
EP0185603B1
EP0185603B1 EP85630204A EP85630204A EP0185603B1 EP 0185603 B1 EP0185603 B1 EP 0185603B1 EP 85630204 A EP85630204 A EP 85630204A EP 85630204 A EP85630204 A EP 85630204A EP 0185603 B1 EP0185603 B1 EP 0185603B1
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EP
European Patent Office
Prior art keywords
layer
turbine air
ceramic
gas turbine
metallic
Prior art date
Legal status (The legal status 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 status listed.)
Expired
Application number
EP85630204A
Other languages
German (de)
English (en)
French (fr)
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EP0185603A1 (en
Inventor
Harry Edwin Eaton
Richard Charles Novak
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Raytheon Technologies Corp
Original Assignee
United Technologies Corp
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Filing date
Publication date
Application filed by United Technologies Corp filed Critical United Technologies Corp
Publication of EP0185603A1 publication Critical patent/EP0185603A1/en
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Publication of EP0185603B1 publication Critical patent/EP0185603B1/en
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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
    • 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
    • C23C4/11—Oxides
    • 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
    • F01D11/00—Preventing or minimising internal leakage of working-fluid, e.g. between stages
    • F01D11/08—Preventing or minimising internal leakage of working-fluid, e.g. between stages for sealing space between rotor blade tips and stator
    • F01D11/12—Preventing or minimising internal leakage of working-fluid, e.g. between stages for sealing space between rotor blade tips and stator using a rubstrip, e.g. erodible. deformable or resiliently-biased part
    • F01D11/122—Preventing or minimising internal leakage of working-fluid, e.g. between stages for sealing space between rotor blade tips and stator using a rubstrip, e.g. erodible. deformable or resiliently-biased part with erodable or abradable material

Definitions

  • the present invention concerns a plasma sprayed graded metal-ceramic gas turbine air seal comprising starting from the substrate an initial metallic bond and a graded layer of ceramic material.
  • the FR-A-918 141 describes a metal-ceramic component comprising a graded layered structure wherein the ceramic fraction changes from 100% at one interface to 0% at the other interface.
  • the temperature of the metallic substrate to which the ceramic coating is applied may be preheated to control either residual stress or coating density. Generally, such heating has been to a uniform temperature.
  • EP-A-0 183 638 broadens the concept and describes methods of continuous grading of mixed metal-ceramic materials.
  • the plasma sprayed graded metal-ceramic gas turbine air seal of the present invention is characterized in that said bond coat is followed by a layer of constant composition of mixed alumina and MCrAIY, wherein M represents iron, nickel and cobalt and mixtures thereof, a graded layer wherein the MCrAIY concentration decreases while simultaneously the alumina concentration increases until a constant composition mixed layer of MCrAIY and A1 2 0 3 is reached, a layer of predominately alumina and an outer layer of predominately zirconia.
  • discrete graded layer seals of the type described in US patent 4 481 237 or continuously graded metal-ceramic seals of the type described in EP-A-0 183 638 are afforded substantially enhanced performance by employing as a ceramic material in the graded portion, a material having a low oxygen permeability at elevated temperatures such as alumina, mullite, or the MgO . A1 2 0 3 spinel.
  • oxidation resistant metallic materials are employed, particularly those of the MCrAIY type (where M is Fe, Ni or Co) and related materials.
  • One such method involves reducing the surface area of the metallic constituent by either limiting the powder size to be relatively coarse and uniform (i.e., reducing the high surface area fine particle content), and/or employing plasma deposition parameters under which the metallic constituent does not melt completely so that upon impact it remains in a rounded form rather than assuming a high surface area splat configuration.
  • Another approach is to preoxidize the metallic constituent.
  • the final concept relates to minimizing the swelling resulting from oxidation of the metallic constituent by deliberately inducing porosity into the material by cospraying a fugitive material along with the metallic-ceramic material.
  • the invention also teaches the use of a thin 100% alumina layer on the mixed layer for purposes of affording total resistance to oxygen penetration and the use of a abradable ceramic layer such as zirconia as the outer seal constituent to provide abradable rubbing contact upon interaction with the moving turbine blading and to provide improved temperature capabilities.
  • the requirements for producing a successful graded metal-ceramic seal may be organized in two categories.
  • the first is the physical requirements of the seal, particularly composition.
  • the second relates to the residual strain which may be built into the system through control of substrate temperature during plasma deposition.
  • This invention is directed at the first category, namely, the physical properties of the graded metal-ceramic layer.
  • Aspects of the second category, namely the control of residual strain will be described as necessary to permit an understanding of the best mode of practicing the invention. These strain control aspects are described in US-A-4,481,237 (which is incorporated herein by reference) for the discrete layer case and in EP-A-0183638 (which is incorporated herein by reference) for the case of continuous grading.
  • Figure 1 illustrates the composition versus thickness of the best seal known to the inventors at the time of the filing of this application.
  • the X axis shows seal thickness in mils and the total seal thickness is approximately 3,81 mm (150 mils). Since the seal is deposited by a plasma deposition, the seal thickness will actually vary in a stepwise fashion from one layer to the next, however, since each layer is in the order of 25.4 ⁇ m (1 mil) thick the continuous curve of Figure 1 is a more than adequate description of the seal composition.
  • an initial metallic bond coat of a composition known as Metco 443 which is a commercially available material formed from an agglomeration of nickel chromium powder and aluminum powder which upon plasma spraying undergoes an exothermic reaction which is believed to aid in the adherence of the bond coat to the substrate.
  • the next 508 ⁇ m (20 mils) are of a constant composition of 60% CoCrAIY (nominal composition of Co-23cr-13AI-0.65Y) having a particule size of 0.044 to 0.149 mm (-100+325 U.S. Standard Sieve) and 40% alumina.
  • Alumina is a harder, stronger material than zirconia and alumina as the outer layer would not have the desired abradable qualities.
  • To further increase the abradability of the zirconia deliberate porosity is induced in the zirconia in the outer portion thereof, pososity on the order of about 19%. This is accomplished by adding a fugitive material (such as Metco 600 polyester or DuPont Lucite®), to the ceramic material and subsequently removing the fugitive by baking at a high temperature to vaporize the fugitive material.
  • a fugitive material such as Metco 600 polyester or DuPont Lucite®
  • a primary aspect of this invention is the substitution of a material which is resistant to the diffusion of oxygen at elevated temperatures.
  • Three such materials have been identified for seal application. These are alumina, mullite and the MgO - A1 2 0 3 spinel.
  • Figure 5 shows the permeability of stabilized zirconia and alumina over a temperature range at 6666 Pa (50 Torr) partial pressure of oxygen. It can be seen that at 1600°C the permeability of oxygen in alumina is less than about 10 -10 and it is about 3 orders of magnitude less than the permeability of oxygen in zirconia at the same temperature.
  • oxidation resistant materials selected from the group consisting of the MCr materials where chromium ranges from about 20 to about 40% the MCrAI materials where chromium ranges from about 15 to about 45% and aluminum ranges from about 7 to about 15%; the MCrAIY materials where chromium ranges from about 15 to about 45%, aluminum ranges from about 6 to about 20% and yttrium ranges from about 0.1 to about 5%; and the MCrAIHf materials where chromium ranges from about 15 to about 45%, aluminum ranges from about 7 to about 15% and hafnium ranges from about 0.5 to about 7%.
  • M is selected from the group consisting of nickel, cobalt, iron and mixtures thereof with mixtures of nickel and cobalt being particularly favored
  • the yttrium when present may be partly or wholly replaced by lanthanum, cerium, Misch metal and mixtures thereof, additionally, up to 10% of a material selected from the group consisting of platinum, tungsten, rhenium, silicon, tantalum and manganese may be added to any of these materials are utilized.
  • Table I presents oxidation data for two compositions based on ceramic-CoCrAIY materials.
  • the ceramic is zirconia and the other the ceramic is alumina, in both compositions the CoCrAIY content was the same volume percent. These materials were tested at 1038°C (1900°F) for 150 hours. The results are presented in the table. It can be seen that the zirconia base material gained 3.3% in weight due to oxidation of the metallic constituent and underwent a longitudinal expansion of 3.4% due to swelling of the material caused by the oxidation of the metallic constituent. Under the same condition the alumina based material gained 2.1% in weight, (a reduction of 37% compared to the zirconia based material), and shrank 0.5% in length.
  • the information in Table I supports the basic premise of the invention which that the substitution of alumina for the commonly used zirconia material in mixed metal-ceramic systems provides substantial seal performance benefits.
  • Table II shows the benefit obtained through minimizing the surface area of the metallic constituent by sieving out the fine particles.
  • both compositions were based on the zirconia ceramic which serves as a valid baseline for demonstrating the benefits obtained by employing coarse particles.
  • Table II shows the weight change results of two materials both of which had the same composition of 85% zirconia, 15% CoCrAIY, the difference between the two samples being that one was produced from a wide size range metallic powder composition of 0.044 to 0.149 mm (-100+325 mesh) while the other was produced from metallic material having 0.074 to 0.149 mm (-100+200 mesh) (the mesh sizes referred to are those described in the U.S.
  • Table III present basic information on the effect of including deliberate porosity on the performance of alumina-CoCrAIY composites produced by plasma spraying. From Table III it is evident that material 'which contained 4% polyester and therefore contains some amount of porosity (about 2%) exhibited slightly increased weight change due to oxidation but rather significantly decreased dimensional changes. Thus, the deliberate inclusion of porosity is an area which will require careful attention by the skilled artisan.
  • the final suggested technique for reducing oxidation and resultant swelling is to perform the plasma spraying under conditions which do not entirely melt the metallic constituent so that the metallic constituent will retain a more nearly spheroidal configuration within the graded coating rather than assuming a completely flattened splat configuration which will result if total melting occurs.
  • Observed aspect ratios (length:thickness) in totally melted materials are from about 5:1 to about 10:1, reduced surface areas result when aspect ratios of about 3:1 or less are produced. This result may be accomplished by adjusting the position within the plasma torch where the metallic constituent is injected so that the metallic constituent has a short residence time within the plasma zone and does not melt completely.
  • the use of coarse particles also assists in controlling aspect ratio.
  • EP-A-0 183 638 describes the temperature management schemes, for continuously graded coatings, which were previously mentioned with respect to Figure 1 and which produce the necessary prestrain in the coating which permit the coating to withstand severe conditions at elevated temperatures without spallation.
  • EP-B-0 185 604 deals with a plasma spray powder management system which has been employed to produce the mixed powder combinations in a highly controllable and reproducible fashion.
  • the essentials of the system are accurate measurements of carrier gas flow and pressure coupled with x-ray measurements of the gas plus powder stream, these measurements are supplied to a controlling microcomputer which generates signals necessary to control the flow and the flow of the various powders.
  • EP-A-0 183 637 deals with the powder flow gauging techniques which are used to measure the actual powder streams and to control their flow.
  • the x-ray gauging system uses flow and pressure sensors to provide accurate measurements of carrier gas flow and uses a transmission x-ray apparatus to give an indication of the total mass flow of powder plus carrier gas. From these measurements the mass flow rate can be accurately calculated. Knowing the actual powder mass flow rate one can employ control circuitry to control and constrain the powder flow rate to follow a predetermined schedule.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Plasma & Fusion (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • General Engineering & Computer Science (AREA)
  • Coating By Spraying Or Casting (AREA)
  • Turbine Rotor Nozzle Sealing (AREA)
EP85630204A 1984-11-28 1985-11-27 Improved durability metallic-ceramic turbine air seals Expired EP0185603B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US67579784A 1984-11-28 1984-11-28
US675797 1984-11-28

Publications (2)

Publication Number Publication Date
EP0185603A1 EP0185603A1 (en) 1986-06-25
EP0185603B1 true EP0185603B1 (en) 1989-11-08

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Family Applications (1)

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EP85630204A Expired EP0185603B1 (en) 1984-11-28 1985-11-27 Improved durability metallic-ceramic turbine air seals

Country Status (3)

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EP (1) EP0185603B1 (sv)
JP (1) JPS61153269A (sv)
DE (1) DE3574168D1 (sv)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0223104A1 (de) * 1985-10-29 1987-05-27 Deutsches Zentrum für Luft- und Raumfahrt e.V. Beschichtung für ein Substrat und Verfahren zu dessen Herstellung
EP0253754A1 (en) * 1986-07-14 1988-01-20 United Technologies Corporation Method for preventing closure of cooling holes in hollow air cooled turbine engine components during application of a plasma spray coating
GB2204881A (en) * 1987-03-24 1988-11-23 Baj Ltd Overlay coating
GB2252567A (en) * 1991-02-11 1992-08-12 Inst Elektroswarki Patona Metal/ceramic protective coating for superalloy articles
WO1993024672A1 (en) * 1992-05-29 1993-12-09 United Technologies Corporation Ceramic thermal barrier coating for rapid thermal cycling applications
EP0965730A3 (en) * 1998-06-18 2001-02-14 United Technologies Corporation Article having durable ceramic coating with localised abradable portion
US6764771B1 (en) * 1997-11-03 2004-07-20 Siemens Aktiengesellschaft Product, especially a gas turbine component, with a ceramic heat insulating layer
CN104841619A (zh) * 2013-12-05 2015-08-19 通用电气公司 涂布方法和用于与该涂布方法一起使用的模板

Families Citing this family (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AT396119B (de) * 1988-04-08 1993-06-25 Stangl Kurt Dipl Ing Verfahren zum beschriften heisser stahlbloecke
AT396120B (de) * 1988-04-13 1993-06-25 Stangl Kurt Dipl Ing Verfahren zum beschriften heisser stahlbloecke
CA2110007A1 (en) * 1992-12-29 1994-06-30 Adrian M. Beltran Thermal barrier coating process
WO1996034128A1 (en) * 1995-04-25 1996-10-31 Siemens Aktiengesellschaft Metal substrate with an oxide layer and an anchoring layer
WO1998004759A1 (en) * 1996-04-12 1998-02-05 Siemens Aktiengesellschaft Metal substrate with an oxide layer and an improved anchoring layer
GB0121429D0 (en) * 2001-09-05 2001-10-24 Trw Ltd A friction member and method of production of same
EP1382707A1 (de) * 2002-07-17 2004-01-21 Siemens Aktiengesellschaft Schichtsystem
JP5210984B2 (ja) * 2009-06-29 2013-06-12 株式会社日立製作所 タービン用高信頼性メタルシール材
FR2994397B1 (fr) 2012-08-07 2014-08-01 Snecma Revetement en materiau abradable a faible rugosite de surface
DE102013213386B3 (de) * 2013-07-09 2014-08-14 MTU Aero Engines AG Strömungsmaschinen-Keramikbauteil
US20170051625A1 (en) * 2015-08-17 2017-02-23 United Technologies Corporation Blade outer air seal component with varying thermal expansion coefficient
US10294962B2 (en) 2017-06-30 2019-05-21 United Technologies Corporation Turbine engine seal for high erosion environment

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4481237A (en) * 1981-12-14 1984-11-06 United Technologies Corporation Method of applying ceramic coatings on a metallic substrate

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR918141A (fr) * 1944-12-01 1947-01-30 Bbc Brown Boveri & Cie Ailette de turbine faite au moins partiellement en poudre frittée de métal et de matière céramique, pour machines travaillant à haute température
US3091548A (en) * 1959-12-15 1963-05-28 Union Carbide Corp High temperature coatings
US3758233A (en) * 1972-01-17 1973-09-11 Gen Motors Corp Vibration damping coatings
JPS526291B2 (sv) * 1972-05-11 1977-02-21
US4255495A (en) * 1979-10-31 1981-03-10 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Corrosion resistant thermal barrier coating
JPS6026964B2 (ja) * 1980-08-20 1985-06-26 ファナック株式会社 警報回路を有するパルスエンコ−ダ装置
CH645925A5 (de) * 1980-12-05 1984-10-31 Castolin Sa Verfahren zur herstellung einer heissgaskorrosionsbestaendigen schutzschicht auf metallteilen und heissgaskorrosionsbestaendige schutzschicht auf metallteilen.
CH648358A5 (en) * 1980-12-05 1985-03-15 Castolin Sa Process for producing a protective layer, resistant to corrosion by hot gas, on metal components
DE3137731A1 (de) * 1981-09-23 1983-04-14 Battelle-Institut E.V., 6000 Frankfurt Hochtemperatur- und thermoschockbestaendige kompaktwerkstoffe und beschichtungen
JPS58167764A (ja) * 1982-03-26 1983-10-04 Toyo Eng Corp 耐熱合金基材の被覆法

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4481237A (en) * 1981-12-14 1984-11-06 United Technologies Corporation Method of applying ceramic coatings on a metallic substrate

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0223104A1 (de) * 1985-10-29 1987-05-27 Deutsches Zentrum für Luft- und Raumfahrt e.V. Beschichtung für ein Substrat und Verfahren zu dessen Herstellung
EP0253754A1 (en) * 1986-07-14 1988-01-20 United Technologies Corporation Method for preventing closure of cooling holes in hollow air cooled turbine engine components during application of a plasma spray coating
GB2204881A (en) * 1987-03-24 1988-11-23 Baj Ltd Overlay coating
GB2204881B (en) * 1987-03-24 1991-04-24 Baj Ltd Overlay coating
GB2252567A (en) * 1991-02-11 1992-08-12 Inst Elektroswarki Patona Metal/ceramic protective coating for superalloy articles
GB2252567B (en) * 1991-02-11 1994-09-14 Inst Elektroswarki Patona Metal/ceramic protective coating for superalloy articles
WO1993024672A1 (en) * 1992-05-29 1993-12-09 United Technologies Corporation Ceramic thermal barrier coating for rapid thermal cycling applications
US6764771B1 (en) * 1997-11-03 2004-07-20 Siemens Aktiengesellschaft Product, especially a gas turbine component, with a ceramic heat insulating layer
EP0965730A3 (en) * 1998-06-18 2001-02-14 United Technologies Corporation Article having durable ceramic coating with localised abradable portion
CN104841619A (zh) * 2013-12-05 2015-08-19 通用电气公司 涂布方法和用于与该涂布方法一起使用的模板

Also Published As

Publication number Publication date
EP0185603A1 (en) 1986-06-25
DE3574168D1 (en) 1989-12-14
JPH0340105B2 (sv) 1991-06-17
JPS61153269A (ja) 1986-07-11

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