TPS for Reusable Launch Vehicles Alloys and Coating ...mln/ltrs-pdfs/NASA-2000-nsmms-wdb.pdfConstituents and Fabrication Development for Metallic TPS - Alloy evaluation ... OBJECTIVES

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


Acreage TPS for Windwardand Leeward Surfaces

Hot Structure Control Surfaces

Leading Edges and Nose Caps

TPS for Reusable Launch Vehicles


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


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


¥ 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


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.


¥ 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


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


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,

%


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


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


Microstructure of Coated 0.003-Inch Thick 602CA Foil

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

coating

foilsurface

S

T


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


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


1.0

0.9

0.8

0.7

0.6

0.5

Oxidation Coating



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


1.0

0.9

0.8

0.7

0.6

0.5


Oxidation CoatingOxidation 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


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


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.


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.


Cryogenic Pressure Box Facility

Check-out panel in facility


¥ 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


Documents

TPS for Reusable Launch Vehicles Alloys and Coating ...mln/ltrs-pdfs/NASA-2000-nsmms-wdb.pdfConstituents and Fabrication Development for Metallic TPS - Alloy evaluation ... OBJECTIVES