TPS for Reusable Launch Vehicles Alloys and Coating...

Alloys and Coating Development for MetallicTPS for Reusable Launch Vehicles

William D. Brewer*Keith Bird*

Terryl Wallace*S.A. Sankaran**

*Metals and Thermal Structures BranchStructures & Materials Competency

NASA Langley Research CenterHampton VA

**Analytical Services and MaterialsHampton VA

Langley ResearchCenter

National Space & Missile Materials Symposium28 Feb. - 2 Mar. 2000

San Diego CA

¥ Constituents and Fabrication Development for Metallic TPS- Alloy evaluation- Coating development

¥ Metallic TPS Concepts- Design/size alternative metallic TPS- Fabricate & test full size panel array- System performance & model validation

¥ Cryogenic Tank Subcomponent Development- Design, fabricate & test full-scale PMC LH2 tank

subcomponent.

¥ Integrated PMC Cryogenic Tank and TPS Structure Demonstration- Full-scale integrated PMC tank/metallic TPS panel tests- Evaluate thermal and mechanical behavior

Reusable Launch VehicleFocused Airframe Systems Technologies

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Acreage TPS for Windwardand Leeward Surfaces

Hot Structure Control Surfaces

Leading Edges and Nose Caps

TPS for Reusable Launch Vehicles

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Metallic TPS

Foil encapsulatedinsulation

Attachment standoffbrackets

Externalcryotank stiffeners

Outer metallichoneycomb

Fasteneraccesscovers

Panel-to-panel seal

X-33 TPS ¥ Outer surface pressure-hot seals ¥ Hot fasteners ¥ Little acoustic/vibration damping ¥ Simpler construction

Alternative Design ¥ Cool, sub-surface pressure seals ¥ Cool, sub-surface fasteners ¥ Unload outer surface from pressure ¥ Provides damping ¥ More complex construction

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TPS Design Concepts

High temp.Insulation

Outer metallichoneycomb

FastenerAccess covers

Inner metallichoneycomb

Cryo foam insulation

Support brackets

Cool surface attachments

Cryogenictank wall

0

500

1000

1500

2000

0 1000 2000 3000 4000

Outer FacesheetInner FacesheetBox Beam TopLower Foil LayerRing FrameFoam SurfaceTank

Reentry time, seconds

Tem

pera

ture

, F

Representative Temperature HistoriesFor RLV Reentry Langley Research

Center

Key Alloy/Surface Requirements

¥ High specific strength and modulus at max service temperature¥ High creep strength¥ Microstructural stability during service life¥ Easily processed to sheet and foil gages¥ Minimum effects of secondary processing¥ Light weight

¥ Oxidation resistant Minimal property degradation¥ Emittance > 0.8 maximize re-radiation¥ Catalytic efficiency <.03 required - minimize heat input

¥ Coating thickness: < 0.002 in. Minimize weight.¥ Cure time: Short - minimize fab.¥ Cure temperature Low - enhance field repair¥ Durability: No crack/spall in handling or service¥ Repair: In the field¥ Service Temp: At least as high as metal operating T.

ALLOYS

COATINGS

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¥ Evaluate candidate alloys and fabrication practice for foil gage product form and TPS concepts

OBJECTIVES

¥ Develop durable, field repairable coatings for environmental protection and thermal control

¥ Improved structural/thermal efficiency¥ Lower weight, lower risk, cost competitive¥ Integrated TPS materials/concepts/structure

EXPECTED RESULTS

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RLV Metallic TPS DevelopmentMaterials Systems for Outer Surface

Prime Candidates

¥ Inconel 617 (X-33 TPS)¥ PM 1000 (MA 754)¥ PM 2000 (MA 956)¥ Titanium Aluminides

- Gamma- Orthorhombic

¥ Conventional titanium alloys (Leeward TPS)

Alternative Alloys

Alloy 602CA (Krupp)- ~10% less dense than In617. Cold roll to foil.

¥ MA 965-HT (Inco High Al alloy)- Better oxidation resistance than standard 956.

¥ CRF Hi Cr alloys (Plansee )- Potential higher temperature use than PMxxxx alloys.

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¥ Effects of fabrication processes and service environments on properties and microstructure

of constituent materials.

¥ Process optimization for maximum panel performance and metallurgical joint efficiency.

¥ Properties of sub-elements in isothermal and simulated mission environments.

Alloy/process Evaluation & DevelopmentLangley Research

Center

Concept for Coating DevelopmentLangley Research

CenterMulti-layer Sol-Gel Coating Design

Reactionbarrier

High emittance layer Low catalysis layer

SubstrateSol-Gel

¥ Thin, light¥ Easily applied (dip, spray, brush)¥ Relatively cheap¥ Field repair¥ Scalable

Effective?

Base layer Sealing layer

Oxidationresistantlayer

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Coatings Evaluation

Static OxidationMech. PropertiesWeight changeMicroscopyEmittance

Thermal ControlDynamic oxidation(Mach 3-4 air flow)Catalytic efficiencyEmittance

Mission simulation (T,P,t)

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60

Exposure time, hrs

Yield strength,

ksi

Yield Strength of 602CA & Inconel 617Sheet and Foil Exposed in Air at 1800¡F

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602CA (0.045-in)

602CA (0.003-in)

602CA (0.002-in)

IN617 (0.006-in)

0

10

20

30

40

50

0 20 40 60

Exposure time, hrs

Plastic strain,

%

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Ductility of 602CA & Inconel 617 Sheetand Foil Exposed in Air at 1800¡F

602CA (0.045-in)

602CA (0.003-in)

602CA (0.002-in)

IN617 (0.006-in)

0

1

2

3

4

0 20 40 60 80 100 120

0

10

20

30

40

0 1 2 3 4

Weightgain,

%

Exposure time, hours

PlasticStrain,

%

Weight gain, %

Performance of Alloy 602CA Sheet & Foilin Air at 1800 oF

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0.045 in. sheet0.003 in. foil0.002 in. foil

Uncoated

Coated

0.003 in. foil

Microstructure of 0.003-Inch Thick 602CA Foil

Uncoated - no exposure Coated - no exposure

Uncoated - 50 hrs @ 1800 oF Coated- 50 hrs @ 1800 oF

50 mm

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Microstructure of Coated 0.003-Inch Thick 602CA Foil

(Exposed In Air at 1800¡F for 50 Hours)

coating

foilsurface

S

T

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Thermal Oxidation of Coated GammaTitanium Aluminide

-1

0

1

2

3

4

5

6

0 50 100

Coated TiAl3 only

Un-coated

TPG-RE/Al2O3

Sealant TPG/TPG-RE/Al2O3Sealant TPG/TPG-RE/TiAl3

Sol-gel sealantSol-gel O2 diffusion barrier (TPG-RE)Reaction Barrier - TiAl3 - Sol-gel Al2O3

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Ti-48Al-2Cr - 1650 ûF

Weight change,mg/cm2

Exposure time, hrs

Effectiveness of Coating System for Oxidation Resistance and Emittance Enhancement

Evaluated on IN-617 After Oxidation Exposure at 1800¡F

Emittance from Total Reflectance Weight Change

Em

itta

nce

Wei

gh

t C

han

ge,

mg

/cm

2

0.4

0.2

0.0

-0.2

-0.4

-0.6

-0.8

Exposure Duration, hours Exposure Duration, hours

0 604020 0 604020

Oxidation Coating

Oxidation + Emittance Coating

Coating Approach

Substrate

Sol-Gel Emittance Coating

Reaction BarrierOxygen Barrier

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1.0

0.9

0.8

0.7

0.6

0.5

Oxidation Coating

Oxidation + Emittance Coating

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Performance of Embedded EmittanceCoating System

Evaluated on IN-617 After Oxidation Exposure at 1800 ¡F

Emittance from Total Reflectance Weight Change

Em

itta

nce

Wei

gh

t C

han

ge,

mg

/cm

2

0.6

0.4

0.2

0.0

-0.2

-0.4

-0.6

Exposure Duration, hours Exposure Duration, hours

0 1208040 0 1208040

Coating Approach

Substrate

Sol-Gel Emittance CoatingReaction Barrier

Oxygen Barrier

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1.0

0.9

0.8

0.7

0.6

0.5

Oxidation + Emittance Coating

Oxidation CoatingOxidation Coating

Oxidation + Emittance Coating

Hypersonic Materials EnvironmentalTest System (HYMETS)

¥ Simulated entry flow environment¥ Mach 3 - 5 air flow¥ 1400 ûF - 2400 ûF

¥ Flow effects on one-inch-diameter specimens¥ Mass change (Oxidation, surface loss)¥ Surface catalytic efficiency measurements¥ Surface emittance of exposed specimens

Test

Specimen

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Candidate Coatings for IN617

-8-7

-6-5-4-3-2-10

0 0.5 1Exposure Time, h

Uncoated Pyromark Sol-Gel Plasmaguard

0

0.1

0.2

0 0.5 1Exposure Time, h

CatalyticEfficiency

WeightChange,mg/cm2

HYMETS Exposure at 1800°FMach 3.5 Air Flow

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Uncoated Sol-Gel coating Commercial coatings

Exposure Time, hoursExposure Time, hours

Alloys

¥ 14 alloys considered- Fe/Ni/Cr superalloys, TiAl

¥ Focusing on PM1000, 602CA, Gamma TiAl

Coatings¥ Good oxidation coatings developed for selected materials

¥ Promising emittance & catalysis coating developed - Need further development & evaluation

Summary - Materials & Coatings TaskLangley Research

Center

- Coating compatibility & environmental effects

- PM1000, IN 617, 602CA, Gamma TiAl

Near Term Activities

¥ Continue to optimize coatings for alloys of choice.- Some emphasis on emittance & catalysis

¥ Validate alloy/coating systems in long term dynamic tests.¥ Assess scale-up/application technique issues for full scale TPS

Alloy/Coating Development & evaluation

Alloy/Processing¥ More focus on joining processes for foil materials.¥ Effects of exposures on face sheet & honeycomb sandwich.

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Design & manufacture full-scale TPS multi-panel array for Integrated TPS/Cryogenic fuel tank component test.

X-37 metallic TPS flight experiment

Full Scale Metallic TPS/Cryo-tank Tests

Design, fabricate & test full scale TPS panel arrayIntegrated with cryo-tank subcomponent.

Thermal Vacuum test - Thermal performance in re-entry temperature/pressure

simulation (1400 - 1800 F)

Cryo-pressure box test - Thermal, mechanical performance in ground hold, fueling, launch & ascent simulation.

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Cryogenic Pressure Box Facility

Check-out panel in facility

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¥ Axial & circumferential mechanical tension loads

¥ Surface thermal load (1000 F)

¥ Backside pressure and cryo thermal loads

Simulate ground hold, fueling, launch, assent

Metallic TPS Experiment For X-37

Multi-Panel Array - Details TBD¥ Location/application

¥ Panel size (6Ó-18Ó) depends on location

¥ Panel-to-panel joint configuration

Technology demonstration¥ First entry flight tests near maximum

heating capability of reusable metallic TPS

¥ Next generation concept

¥ Advanced metallic materials/fabrication

¥ New surface coatings

¥ Optimized insulation package

¥ Efficient attachment scheme

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