Thermal And Environmental Barrier Coatings For Advanced .
NASA/TM—2005-213437Thermal and Environmental Barrier Coatingsfor Advanced Turbine Engine ApplicationsDongming ZhuU.S. Army Research Laboratory, Glenn Research Center, Cleveland, OhioRobert A. MillerGlenn Research Center, Cleveland, OhioMarch 2005
The NASA STI Program Office . . . in ProfileSince its founding, NASA has been dedicated tothe advancement of aeronautics and spacescience. The NASA Scientific and TechnicalInformation (STI) Program Office plays a key partin helping NASA maintain this important role. CONFERENCE PUBLICATION. Collectedpapers from scientific and technicalconferences, symposia, seminars, or othermeetings sponsored or cosponsored byNASA.The NASA STI Program Office is operated byLangley Research Center, the Lead Center forNASA’s scientific and technical information. TheNASA STI Program Office provides access to theNASA STI Database, the largest collection ofaeronautical and space science STI in the world.The Program Office is also NASA’s institutionalmechanism for disseminating the results of itsresearch and development activities. These resultsare published by NASA in the NASA STI ReportSeries, which includes the following report types: SPECIAL PUBLICATION. Scientific,technical, or historical information fromNASA programs, projects, and missions,often concerned with subjects havingsubstantial public interest. TECHNICAL TRANSLATION. Englishlanguage translations of foreign scientificand technical material pertinent to NASA’smission. TECHNICAL PUBLICATION. Reports ofcompleted research or a major significantphase of research that present the results ofNASA programs and include extensive dataor theoretical analysis. Includes compilationsof significant scientific and technical data andinformation deemed to be of continuingreference value. NASA’s counterpart of peerreviewed formal professional papers buthas less stringent limitations on manuscriptlength and extent of graphic presentations.TECHNICAL MEMORANDUM. Scientificand technical findings that are preliminary orof specialized interest, e.g., quick releasereports, working papers, and bibliographiesthat contain minimal annotation. Does notcontain extensive analysis.CONTRACTOR REPORT. Scientific andtechnical findings by NASA-sponsoredcontractors and grantees.Specialized services that complement the STIProgram Office’s diverse offerings includecreating custom thesauri, building customizeddatabases, organizing and publishing researchresults . . . even providing videos.For more information about the NASA STIProgram Office, see the following: Access the NASA STI Program Home Pageat http://www.sti.nasa.gov E-mail your question via the Internet tohelp@sti.nasa.gov Fax your question to the NASA AccessHelp Desk at 301–621–0134 Telephone the NASA Access Help Desk at301–621–0390 Write to:NASA Access Help DeskNASA Center for AeroSpace Information7121 Standard DriveHanover, MD 21076
NASA/TM—2005-213437Thermal and Environmental Barrier Coatingsfor Advanced Turbine Engine ApplicationsDongming ZhuU.S. Army Research Laboratory, Glenn Research Center, Cleveland, OhioRobert A. MillerGlenn Research Center, Cleveland, OhioPrepared for the2004 Fall Meetingsponsored by the Materials Research SocietyBoston, Massacusetts, November 29–December 03, 2004National Aeronautics andSpace AdministrationGlenn Research CenterMarch 2005
Available fromNASA Center for Aerospace Information7121 Standard DriveHanover, MD 21076National Technical Information Service5285 Port Royal RoadSpringfield, VA 22100Available electronically at http://gltrs.grc.nasa.gov
Thermal and Environmental Barrier Coatings for AdvancedTurbine Engine ApplicationsDongming ZhuU.S. Army Research LaboratoryGlenn Research CenterCleveland, Ohio 44135Robert A. MillerNational Aeronautics and Space AdministrationGlenn Research CenterCleveland, Ohio 44135AbstractCeramic thermal and environmental barrier coatings (T/EBCs) will play a crucial role in advancedgas turbine engine systems because of their ability to significantly increase engine operating temperaturesand reduce cooling requirements, thus help achieve engine low emission and high efficiency goals. Underthe NASA Ultra-Efficient Engine Technology (UEET) program, advanced T/EBCs are being developedfor the low emission SiC/SiC ceramic matrix composite (CMC) combustor applications by extending theCMC liner and vane temperature capability to 1650 C (3000 F) in oxidizing and water vapor containingcombustion environments. Advanced low conductivity thermal barrier coatings (TBCs) are also beingdeveloped for metallic turbine airfoil and combustor applications, providing the component temperaturecapability up to 1650 C (3000 F). The advanced T/EBC system is required to have increased phasestability, low lattice and radiation thermal conductivity, and improved sintering, erosion and thermalstress resistance, and water vapor stability under the engine high-heat-flux and thermal cyclingconditions. Advanced high heat-flux testing approaches have been established for the coatingdevelopments. The simulated combustion water-vapor environment is also being incorporated into theheat-flux test capabilities for evaluating T/EBC performance at very high temperatures under thermalcycling conditions.In this paper, ceramic coating development considerations and requirements for both the ceramic andmetallic components will be described for engine high temperature and high-heat-flux applications. Theperformance and durability of several ZrO2 or HfO2/mullite and mullite/BSAS model coating systemswere investigated. The underlying coating failure mechanisms and life prediction approaches will bediscussed based on the simulated engine tests and fracture mechanics modeling results. Further coatingperformance and life improvements will be expected by utilizing advanced coating architecture design,composition optimization, in conjunction with more sophisticated modeling and design tools.NASA/TM—2005-2134371
NASA/TM—2005-213437Thermal and Environmental Barrier Coatings forAdvanced Turbine Engine ApplicationsDongming Zhu and Robert A. Miller3Durability and Protective Coatings Branch, Materials DivisionNASA John H. Glenn Research CenterCleveland, Ohio 44135, USAThis work was supported by NASA Ultra-Efficient Engine Technology (UEET) Program2004 MRS Fall MeetingBoston, MANovember 30, 2004
NASA/TM—2005-213437Motivation— Advanced thermal and environmental barrier coatings (T/EBCs) cansignificantly increase gas temperatures, reduce cooling requirements,and improve engine fuel efficiency and reliabilityTgasCombustorVaneTurbine coatingBondcoatMetalsubstrate(a) Current T/EBCsCeramiccoatingBondcoatMetalsubstrate(b) Advanced T/EBCs
NASA/TM—2005-213437Revolutionary Ceramic Coatings Greatly Impact GasTurbine Engine Technology— Ceramic coatings are critical to future engine efficiency, power densityand compactness goalsTemperatureCapability(T/EBC) surface3000 F (1650 C )Increase in Tacross T/EBC5Ceramic Matrix Composite2700 FSi3N4 and coating systems2400 FSingle Crystal SuperalloyGen IIIGen II – Current commercialGen IGen. IVYearCoating Development Issues Low thermal conductivity High temperature stability Erosion and radiation resistanceNASA UEET Goals 70% NOx reduction 8-15% increase in efficiency 8-15% reduction in CO2
NASA/TM—2005-213437OBJECTIVES High-heat-flux and simulated engine test capabilities for advancedbarrier coating developments– In-situ conductivity measurements and coating degradationevaluation– Simulated engine testing– Sintering, strength and fracture behavior6 Low conductivity thermal barrier coatings The 3000 F (1650 C) thermal and environmental barrier coatingsfor SiC/SiC CMC and metallic combustors/vanes Advanced Si3N4 coating systems
NASA/TM—2005-213437NASA Steady-State Laser Heat-Flux Approach forCeramic Coating Thermal Conductivity Measurements A uniform laser (wavelength 10.6 µm) power distribution achieved using integratinglens combined with lens/specimen rotation The ceramic surface and substrate temperatures measured by 8 micron and two-colorpyrometers and/or by an embedded miniature thermocouple Thermal conductivity measured at 5 second intervals in real time7laser beam/integrating lensreflectometer300 RPM3. 0 KW CO 2 High Power Laserpyrometerair gapplatinum flat coilsaluminum laseraperture platecameraceramic coatingbond coatminiaturethermocoupleTBC coatedback aluminumplate edgespecimenslip ringthermocouplealuminum back platecooling aircooling air tubeCMSX4substrateNi-basesuperalloyor CMC substrate
NASA/TM—2005-213437Laser Heat Flux Testing in Water Vapor Environmentsfor Si-Based Ceramics/Coatings– Laser heat flux steam rig- Precise control of heat flux and temperatures of test specimen- Automated control of chamber temperature and steam environments- High temperature and high heat flux testing capabilities- Innovative “micro-steam environment” concept allows high vapor pressure,velocity and temperature as required- Real time specimen health monitoring capability87.9 µm pyrometerfor Tceramic-surfaceLaser beam deliveryand optic systemSurface flowqradiatedqreflectedSteam jetsceramic coatingInfraredpyrometerbond coat Tceramic Tmeasuredqthru TtcSpecimen holder and water vapor jetsTwo-color and 7.9 µmpyrometers forTsubstrate-back Tsubstrate TbondsubstrateqthruOptional miniaturethermocouple for additionalheat flux calibration- Steam injected at up to 5m/sec- Testing temperature 1700 CLaser heat flux water vapor test rigSpecimen under testing
NASA/TM—2005-213437High Pressure Burner Rig (HPBR) forCeramic Coatings Testing- Realistic combustion environments for specimen and component testing Test Section9Combustor Burns jet fuel and airTgas: up to 1650 C (3000 F)4-12 atmospheres10-30 m/s (6” ID)TC and optical temp.measurementVariable geometryRail System1” button TEBC coating specimenholder for the burner rig testing
NASA/TM—2005-213437Thermal Conductivity of Current ThermalBarrier Coating SystemsCurrent thermal barrier coatings consist of ZrO2-8wt%Y2O3— relatively low intrinsic thermal conductivity 2.5 W/m-K— high thermal expansion to better match superalloy substrates— good high temperature stability and mechanical properties— Additional conductivity reduction is achieved by incorporating micro-porosity10Ceramic coatingCeramic coatingBond coat100 µm(a) Plasma-sprayed coatingBond coat25 µ m(b) EB-PVD coating
NASA/TM—2005-213437Coating Thermal Conductivity Reductions byPorosity are limited in Practical Applications—The conductivity reduction achieved by microcracks and micro-porositycan not persist under high temperatures due to coating sintering—The coating mechanical properties also affected by too high porosity11Thermal conductivity, W/m-K3.0Conductivity reduction by microcracks and microporosity2.52.01.51.0k2020-hr riseat 1316 Ck2020-hr riseat 1316 Ck00.5Intrinsic ZrO2-Y2O3conductivityk0As receivedConductivity k0(EB-PVD)As receivedConductivity k0(Plasma Coating )0.0Plasma-sprayed TBCEB-PVD TBCCoating Type
NASA/TM—2005-213437ZrO2-8wt%Y2O3/Mullite BSAS/Si System under HighTemperature Steady-State Laser Heat-Flux Testing— ZrO2-8wt%Y2O3/mullite BSAS TEBC system on SiC/SiC CMC tested atTsurface1482 C (2700 F) and Tinterface 1300 C (2350 F)— Conductivity initially increased due to sintering— Conductivity later decreased due to delamination resulting from the largesintering shrinkage— Coating delaminates at temperature due to sintering/creepConductivity reduction due tosintering cracking induceddelamination crackingAfter 20h testing3.0Thermal conductivity, W /m -K122.52.0Sintering cracksZrO2-Y2O3Mullite BSASSiTsurface 1482 CTinterface 1250 C1.51.0M easured thermal conductivityPredicted thermal conductivity0.50.00510Time, hours1520500 mm
NASA/TM—2005-213437Sintering Behavior of the Plasma-SprayedZrO2-8wt%Y2O3 Coatings—―Sintering shrinkage as a function of time and temperature determinedusing dilatometerSintering can induce surface cracking and delaminationZrO2-8wt%Y2O3/Mullite BSAS/Si System2000.02Energy release rate, J/mShrikage strains, %13-0.2150-0.4G thru D1500 CG delaDmin-0.61001500 CEG thru D-0.81400 C 60GPaTBC50-1.0GGdelaDmin1400 C0-1.20510Time, hours1520C
NASA/TM—2005-213437Thermal Conductivity Increase Kinetics of PlasmaSprayed ZrO2-8wt%Y2O3 Coatings due to Sintering—The conductivity reduction by microcracks and micro-porosity can notpersist under high temperatures due to coating sintering—The coating durability can be affected by sinteringThermal conductivity ZrO2-8wt%Y2O3 as a function of time andtemperature at up to 1320 C140.60 68228 t 102.2 exp 1 exp k cinf k c0 RT τ 41710 τ 572.5 exp RT k c k c00.50lnk at 990 Clnk at 1100 Clnk at 1320 Clnk, W/m K0.400.300.200.100.00-0.1015000lnk -0.560 2.9326·10-5 L-M200002500030000L-M Tave·[lnt 10]35000
NASA/TM—2005-213437Flexure Strength and Toughness Increases Kinetics as aFunction of Annealing/Sintering Time140120100806040Flexure testing2000100200300400ANNEALING TIME, t [h]500600FRACTURE TOUGHNESS [MPa m1/2]15FLEXURE STRENGTH, σf [MPa]— Initially fast sintering induced strength and fracture toughness increasesalso observed for plasma-sprayed ZrO2-8wt%Y2O3 coatings3.0KIc2.52.0KIIc1.5BS.DA1.0A0.5Mode I KIcSBMode II KIIc0.00100200300400ANNEALING TIME, t [h]500600
NASA/TM—2005-213437Development of Advanced Defect Cluster LowConductivity Thermal Barrier Coatings— Multi-component oxide defect clustering approach used for the advancedcoating development – US Patent No. 6,812,176e.g., ZrO2-Y2O3-Nd2O3(Gd2O3,Sm2O3)-Yb2O3(Sc2O3) systemsPrimary stabilizerOxide cluster dopants with distinctive ionic sizes16— Defect clusters associated with the dopant segregation identified frommoiré fringe patterns and electron energy loss spectroscopy (EELS)under high resolution TEM— The 5 to 100 nm size defect clusters designed for the significantly reducedthermal conductivity and improved stabilityPlasma-sprayed ZrO213.5mol%(Y, Nd,Yb)2O3EB-PVD ZrO2-12mol%(Y,Nd,Yb)2O3EELS elemental maps of EB-PVD ZrO214mol%(Y, Gd,Yb)2O3
NASA/TM—2005-213437Low Conductivity Oxide Defect Cluster CoatingsDemonstrated Improved High Temperature Stability— Thermal conductivity rate-of-increase significantly reduced at hightemperatures for the low conductivity defect cluster thermal barriercoatings— Phase stability also improved17Thermal conductivity, W/m-K2.01316 C1.81.6ZrO2-4.55mol%Y2O3 (ZrO2-8wt%Y2O3 )1.4rate increase: 2.65 10-6 W/m-K-s1.21.0ZrO -13.5mol%(Y,Nd,Yb) O0.820.623rate increase: 2.9 10-7 W/m-K-s0.4051015Time, hours20Plasma-sprayed coatings25
NASA/TM—2005-213437Low Conductivity Oxide Defect Cluster CoatingsDemonstrated Improved High Temperature Stability— Thermal conductivity rate-of-increase significantly reduced at hightemperatures for the low conductivity defect cluster thermal barriercoatings— Phase stability also improved2.51371 C18Thermal conductivity, W/m-K-6rate increase: 2.2-3.8 10 W/m-K-s2.01.5rate increase: 6.0 10-7 W/m-K-s1.0ZrO -4mol%Y O (ZrO -7wt%Y O )20.523223ZrO2-4mol%Y2O3 (ZrO2-7wt%Y2O3 )Low conductivity ZrO2-10mol%(Y,Gd,Yb)2O3 coating0.0051015Time, hoursEB-PVD coatings2025
NASA/TM—2005-213437Thermal Conductivity of Oxides Cluster ThermalBarrier Coatings Tested at Higher Temperatures― Both cubic phase low k coatings and t’ tetragonal plasma-sprayedcoatings showed significantly lower thermal conductivity as comparedto baseline ZrO2-8wt%Y2O3 under higher temperatures19Thermal conductivity, sedcoatings1.41.28YSZ k0 (2500F)8YSZ k20 (2500F)8YSZ k0 (2600F)8YSZ k20 (2600F)k0 Refractron k0 ( 2500F)k20Refractron k20 ( 2500F)k0 Refractron k0 ( 2700F)k20Refractron k20 ( 2700F)k0 Praxair k0 (2500F)k20Praxair k20 (2500F)k0 NASA k0 (2500F)k20NASA k20 (2500F)1.00.80.60.424681012Total dopant concentration, mol%t’ phase regionCubic phase region14
NASA/TM—2005-213437Furnace Cyclic Behavior of Plasma-Sprayed ZrO2(Y,Gd,Yb)2O3 Thermal Barrier Coatings― The cubic-phase ZrO2-based low conductivity TBC durability can be furthersignificantly improved by an 8YSZ or low k tetragonal t’-phase interlayer― The tetragonal t’-phase low conductivity TBCs achieved at least thebaseline 8YSZ life100020800Cycles to failure1135 CCubic phase low k TBCTetrogonal t' phase low k TBCs8YSZWith theinterlayer600400Low-k t’-phaseregion200WithoutinterlayerLow-k cubicphase region2075 F (1135 C)045678910Total dopant concentration, mol%1112
1.5Howmet processed NASAcoating tested at 1371 C(2500 F)&1204 F (2200 F)21k0-2500F-low k coatingsk20-2500F-low k coatingsk0-2200F-low k coatingsk20-2200F-low k coatings1.030.5Howmet processed NASAcoating furnace cyclic testedat 1165 C (2125 F)Bond coat &interfaceprocessingoptimization21Normalized cyclic life-low k coatings00.0Cluster dopants/ Total dopants in mol%/mol%Normalized cyclic life(to the low ratio dopant coating)― Optimized dopant ratio lowered coating conductivity and improved furnacecyclic life― Bond coat and interface processing optimization can also improvedurabilityNormalized thermal conductivity, W/m-K(to the low ratio dopant coating)NASA/TM—2005-213437Effects of Defect Cluster Dopant Ratio and Bond CoatOptimization on Coating Conductivity and Furnace Cyclic Life
NASA/TM—2005-213437Low Diffusion and High Toughness CoatingsShowed Better Cyclic LifeZrO2-13.5mol%(Y,Gd,Yb)2O3Coating after 430, 1 hrcycles at 1165 CHigh toughness t’ phase such as in 8YSZ2 µm2210.010.0 umumFracture surfacesLarger grainsFast grain growth and low toughnessZrO2-10mol%Y2O3Observed grain growth, µ m6 .0C lu ster o x ide coatin gY S Z co ating5 .01165 C4 .03 .02 .01 .00 .0051015202530T o tal d op an t co ncentratio n, m ol%35
NASA/TM—2005-213437Advanced Low Conductivity TBC Showed ExcellentLong-Term High Temperature Cyclic Durability― The low conductivity combustor and turbine airfoil thermal barriercoatings successfully tested under laboratory simulated engine thermalgradient cyclic conditions23Cycle number100015001.62.07YSZ: Tsurface 2700 F/Tinterface 2030 F30 min cyclic after 20 hr steady-state sintering test1.51.0spallation0.5Low k 256:Tsurface 2800 F/Tinterface 2030 F200, 30 min cyclic after 20hr steady-state sintering test0.0Thermal conductivity, W/m-KThermal conductivity, W/m-K2.5050020002500Tsurface 2480 F (1360 C)Tinterface 2020 F(1104 C)1.41.21.0Low conductivity EB-PVD turbineairfoil coating0.80.66 min heating, 2 min cooling cycles0.4020406080Time, hours100120140050100150200Time, hours250300350
― Advanced high toughness, multi-component erosion resistant low35024Erosion EB-PVD coatingsImpactHigh toughness, tetragonalphase multi-component coating300250200150 ZrO -7wt%Y O210023Cubic-phasemulti-component coating500Baseline coatingLow conductivity coatingCoating type(a) Burner rig erosion and impact testresults at 2200 FErosion and impact resistance(specific erodent required per coating weight loss),g/mgconductivity thermal barrier coatings also under developmentErosion and impact resistance(specific erodent weight required to penetrate coating),mg/mil coating thicknessNASA/TM—2005-213437Development of Advanced Erosion Resistant ThermalBarrier Coatings3.0Erosion & Impact Plasma-sprayed coatings2.5High toughness, tetragonal phasemulti-component coating2.0ZrO -8wt%Y O2231.51.0Cubic-phasemulti-component coating0.50.0Baseline coatingLow conductivity coatingCoating type(b) Room temperature erosiontesting results for 2400 F thermalgradient tested specimens
NASA/TM—2005-213437Advanced 3000 F (1649 C) Coatings— High temperature stability— Low thermal conductivity— Excellent thermal stress resistance— Enhanced radiative flux resistance and radiation cooling— Improved environmental protection— Designed functional capability25High temperature capabilitythermal and radiation barrierEnergy dissipation and chemicalbarrier interlayerSecondary radiation barrier, thermalc
barrier coating developments – In-situ conductivity measurements and coating degradation evaluation – Simulated engine testing – Sintering, strength and fracture behavior Low conductivity thermal barrier coatings The 3000 F (1650 C) thermal and environmental barrier coatings for SiC/SiC CMC and metallic combustors/vanes .
Thermal Barrier Coatings, as the name suggests are coatings which provide a barrier to the flow of heat. Thermal Barrier Coatings (TBC) performs the important function of insulating components such as gas turbine and aero engine parts operating at elevated temperatures. Thermal barrier coatings (TBC) are layer systems deposited on
HENRY AIR-BLOC 31MR VAPOR PERMEABLE AIR BARRIER MEMBRANE: Air and Water Resistive Barrier Coatings HENRY AIR-BLOC 32MR LIQUID EMULSION AIR AND VAPOR BARRIER MEMBRANE; Air and Water Resistive Barrier Coatings HENRY AIR-BLOC 33MR UV RESISTANT, VAPOR PERMEABLE AIR AND
Depositing thermal barrier coatings (TBCs) onto engine components has been demonstrated to have great potential to reduce heat loss from the combustion chamber as well as from exhaust components. The overall aim of this thesis is to evaluate the thermal cycling lifetime and thermal insulation properties of TBCs for the purpose of reducing heat
VANSIL W is an excellent extender pigment for powder coatings as well as solvent-thinned and latex paints. VANSIL W-50 disperses to a to egman fineness at three pounds per gallon. This grade is suitable for liquid industrial and corrosion resistant coatings, powder coatings, and semi-gloss architectural coatings. n powder coatings, this grade
the associated degradation of TBCs are therefore the primary focus of this article. This article is or ganized into three main sections. The fi rst section discusses the thermomechanical problem and the asso-ciated driving forces. The second addresses thermochemical Environmental degradation of thermal-barrier coatings by molten deposits
for thermal expansion differences between it and the base material. The ASPS process presents an economical alternative to EB-PVD to produce durable columnar TBCs. 1 Introduction . Thermal barrier coatings (TBCs) have been employed for many years to protect the
Barrier Options 2.1 Barrier Option Basics A barrier option is a kind of path-dependent options that comes into exis-tence or is terminated depending on whether the underlying asset's price S reaches a certain price level H called "barrier". A knock-out option ceases to exist if the underlying asset reaches the barrier, whereas a knock-in .
Introduction 1 Part I Ancient Greek Criticism 7 Classical Literary Criticism: Intellectual and Political Backgrounds 9 1 Plato (428–ca. 347 bc)19 2 Aristotle (384–322 bc)41 Part II The Traditions of Rhetoric 63 3 Greek Rhetoric 65 Protagoras, Gorgias, Antiphon, Lysias, Isocrates, Plato, Aristotle 4 The Hellenistic Period and Roman Rhetoric 80 Rhetorica, Cicero, Quintilian Part III Greek .
