Progress in Manufacturing & Characterizing Domestic Lyocell PICA (PICA-D) and Comparison to Heritage PICA Ethiraj Venkatapathy, Mairead Stackpoole and Matthew Gasch, NASA Ames Research Center, Moffett Field, CA 94035 Steve Violette, Fiber Materials Inc., Biddeford, ME 04005 1. Background – PICA and PICA Sustainability State of the Art Low Density Carbon Phenolic Ablators Stardust SRC post flight with PICA forebody heat shield (0.8m max. diameter) Acknowledgements PICA sustainability activities are funded by NASA’s Planetary Science Division of the Science Mission Directorate Net Casting, Billet Fabrication and Infusion Trimmed prior to infusion Post-infusion Post-gel Trimmed X-ray (fiber alignment and FOD/void check Cast unit density coupon cut plan Density (g/cc) Failure Stress (psi) Average Lyocell IP properties 0.28 246.48 (vs 190 for rayon PICA) Average Lyocell TTT properties 0.28 44.03 (vs 49.6 for rayon PICA) Mechanical Property Comparison Thermal Property Comparison Billet ID Specimen ID Thermal Conductivity (BTU-in/hr-ft 2 - o F) at 100°F at 350°F Average Lyocell TTT properties 0.939 1.32 Average Rayon TTT properties 1.22 1.66 • In 2016 NASA ARC learned that the heritage rayon utilized in PICA was stopping production, leading to a flight-qualified PICA sustainability challenge • In FY16/17, NASA ARC was funded by SMD/PSD to address PICA rayon sustainability • Lyocell Based PICA (PICA-D) was manufactured and limited testing performed showing it to be a good candidate as a potential replacement for heritage rayon • Phenolic Impregnated Carbon Ablator (PICA) is a low density (~ 0.27g/cm 3 ) ablator first used as the forebody heatshield for the Stardust sample return capsule where it was used as a single piece heatshield • Since Stardust, PICA was used on the Mars Science Lab (MSL) in a tiled configuration, on the OSIRIS-REx sample return capsule as a single piece and slated for Mars 2020 as a tiled configuration PICA Processing Steps Role of Rayon/Lyocell in PICA Manufacturing Rayon or Lyocell Conversion to carbon FiberForm ® billet preform Single piece PICA heatshield (< 1.00 m max diameter) Near net shape preform Tiled PICA heat shield (> 1.00 m max diam) Raw material sustainability concern 4. Exploration of Lyocell PICA (PICA-D) for Future Missions 5. PICA-D Project Schedule Lyocell is a sustainable domestic source of a “rayon alternative” fiber that can be used in the manufacture of carbon FiberForm®, the precursor to PICA. • Establishing PICA-D as a “drop in replacement” will allow missions to depend on and design missions with PICA without any risk typical of a replacement. • Establishing the extended capability of PICA-D will allow Sample Return Missions with higher entry speed that were not considered before. Task 1: Establish PICA-D as a Drop-in replacement for Heritage PICA – Develop comprehensive material property database • Perform comprehensive material property testing (range of temperatures) for thermal and mechanical properties – Perform comprehensive arcjet test campaign • Test at multiple conditions, including different material lots • Testing to include thermal response, instrumented stagnation and wedge shear coupons – Develop PICA-D Thermal Response Model utilizing arcjet test data and new material property database Task 2: Establish the Expanded Capability (Extensibility) of PICA-D – Demonstrate Manufacturing and Scale-Up of a Single Piece Heatshield at a Scale of > 1.2m Diameter • Perform comprehensive characterization and evaluation of single piece FiberForm casting • Characterize fiber alignment, mechanical properties and non-destructive evaluation (NDE) – Establish Expanded Design Space of PICA-D • Perform arcjet testing and heat flux / pressure conditions beyond which PICA has previously been tested and / or flown – Publish all PICA-D Data for current and future missions In FY18/FY19, NASA Ames is leading an effort funded by SMD-PSD to characterize and extend the capability of PICA-D to Establish Lyocell PICA as a Drop-In Replacement for Heritage PICA 2. Establishment of PICA-D as a Replacement for Heritage PICA • In FY17, SMD-PSD funded ARC to manufacture and perform limited property and aerothermal characterization of Lyocell-based PICA – FY17 task successfully completed limited testing that indicated the viability of PICA-D as a potential replacement for heritage PICA Material Property Characterization • In FY17, 3 billets of PICA-D were manufactured to support testing – Limited In-plane (IP) tension, through-thickness (TT) tension, and through thickness thermal conductivity at 100F and 350F were conducted and compared to heritage rayon PICA • Overall these results are in family with production rayon PICA – however additional testing is needed as only a few coupons were evaluated – Limited property data had substantial scatter – detailed testing planned for FY18/19 3. Establishment of PICA-D Expanded Capability • 9 billets of FiberForm were manufactured in FY17 to optimize the process using Lyocell fibers – Billets spanned the spec density range and billet FiberForm target densities were achieved • Development and fabrication of 3 0.8-m net-shaped FiberForm heatshield blank (OSIRIS REx scale) were also completed in FY17 – Density targets in all 3 net cast blanks were achieved • Process refinements and lessons learned have been documented • Limited Non Destructive Evaluation (NDE) completed on the Lyocell near net shape FiberForm unit to evaluate fiber alignment and check for off-nominal features • FY18/19 work will expand on the work performed in FY17 and demonstrate repeatability as well as increase single piece net cast dimensions to >1.2-m Arc Jet Characterization Material Average centerline recession (1550W/cm 2 and 1.3 atm) Average centerline recession (400W/cm 2 and 0.3atm) Average centerline recession (220W/cm 2 and 0.08atm) Lyocell Derived PICA 4.0mm 6.02mm 3.79mm Rayon Derived PICA 4.2mm 5.97mm 3.89mm Rayon Derived PICA Lyocell Derived PICA Post test Post test Pre test Pre test Lyocell Derived PICA Rayon Derived PICA Example in-depth TC Trace @ 1550W/cm 2 Recession Comparison • 3 arcjet conditions were tested in FY17 - NF proposers provided guidance on test conditions - All conditions will be repeated in FY18/19 to demonstrate data repeatability For a given test condition (same run time) initial results indicate that recession and in-depth temperature between a Lyocell derived PICA and a heritage rayon-derived PICA are comparable • NASA ARC is working with SMD-PSD to address PICA rayon sustainability concerns • In FY16/17, Lyocell Based PICA (PICA-D) was manufactured and limited testing performed showing it to be a good candidate as a potential replacement for heritage rayon • Establishing PICA-D as a “drop in replacement” will allow missions to depend on and design missions with PICA without any risk typical of a replacement. • Establishing the extended capability of PICA-D will allow Sample Return Missions with higher entry speed that were not considered before. 6. Summary 0 200 400 600 800 1000 1200 1400 1600 1800 0 0.2 0.4 0.6 0.8 1 1.2 1.4 Stag Point Total Margined CW Heat Flux, W/cm 2 Stag Pressure, atm Arcjet Test Conditions Dragonfly Commet Sample Return Stardust
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ProgressinManufacturing &Characterizing DomesticLyocellPICA(PICA-D)andComparisontoHeritagePICAEthirajVenkatapathy,MaireadStackpooleandMatthewGasch,NASAAmesResearchCenter,MoffettField,CA94035
SteveViolette,FiberMaterialsInc.,Biddeford,ME04005
1.Background– PICAandPICASustainabilityStateoftheArtLowDensityCarbonPhenolicAblators
StardustSRCpostflightwithPICAforebodyheatshield(0.8mmax.diameter)
AcknowledgementsPICAsustainabilityactivitiesarefundedbyNASA’sPlanetaryScience
DivisionoftheScienceMissionDirectorate
NetCasting,BilletFabricationandInfusion
TrimmedpriortoinfusionPost-infusion
Post-gel
Trimmed X-ray(fiberalignmentandFOD/voidcheck
Castunitdensitycouponcutplan
Density(g/cc) FailureStress(psi)
AverageLyocellIPproperties 0.28
246.48
(vs190for rayonPICA)AverageLyocellTTTproperties 0.28
44.03
(vs49.6for rayonPICA)
MechanicalPropertyComparison ThermalPropertyComparison
BilletID SpecimenID
ThermalConductivity(BTU-in/hr-ft2-oF)at100°F at350°F
AverageLyocellTTTproperties 0.939 1.32
AverageRayonTTTproperties 1.22 1.66
• In2016NASAARClearnedthattheheritagerayonutilizedinPICAwasstoppingproduction,leadingtoaflight-qualifiedPICAsustainabilitychallenge
• InFY16/17,NASAARCwasfundedbySMD/PSDtoaddressPICArayonsustainability
• LyocellBasedPICA(PICA-D)wasmanufacturedandlimitedtestingperformedshowingittobeagoodcandidateasapotentialreplacementforheritagerayon
• PhenolicImpregnatedCarbonAblator(PICA)isalowdensity(~0.27g/cm3)ablatorfirstusedastheforebodyheatshieldfortheStardustsamplereturncapsulewhereitwasusedasasinglepieceheatshield
• SinceStardust,PICAwasusedontheMarsScienceLab(MSL)inatiledconfiguration,ontheOSIRIS-REx samplereturncapsuleasasinglepieceandslatedforMars2020asatiledconfiguration
PICAProcessingSteps
RoleofRayon/LyocellinPICA
Manufacturing
RayonorLyocellConversiontocarbon
FiberForm® billetpreform
SinglepiecePICAheatshield(<1.00mmaxdiameter)Nearnetshapepreform
TiledPICAheatshield(>1.00mmaxdiam)
Rawmaterialsustainability
concern
4.ExplorationofLyocellPICA(PICA-D)forFutureMissions
5.PICA-DProjectSchedule
Lyocellisasustainabledomesticsourceofa“rayonalternative”fiberthatcanbeusedinthemanufactureofcarbonFiberForm®,theprecursortoPICA.
• EstablishingPICA-Dasa“dropinreplacement”willallowmissionstodependonanddesignmissionswithPICAwithoutanyrisktypicalofareplacement.
• EstablishingtheextendedcapabilityofPICA-DwillallowSampleReturnMissionswithhigherentryspeedthatwerenotconsideredbefore.
Task1:EstablishPICA-DasaDrop-inreplacementforHeritagePICA
– Developcomprehensivematerialpropertydatabase• Performcomprehensivematerialpropertytesting(rangeoftemperatures)forthermalandmechanicalproperties
– Performcomprehensivearcjettestcampaign• Testatmultipleconditions,includingdifferentmateriallots• Testingtoincludethermalresponse,instrumentedstagnationandwedgeshearcoupons
– DevelopPICA-DThermalResponseModelutilizingarcjettestdataandnewmaterialpropertydatabase
Task2:EstablishtheExpandedCapability(Extensibility)ofPICA-D
– DemonstrateManufacturingandScale-UpofaSinglePieceHeatshieldataScaleof>1.2mDiameter• PerformcomprehensivecharacterizationandevaluationofsinglepieceFiberFormcasting• Characterizefiberalignment,mechanicalpropertiesandnon-destructiveevaluation(NDE)
– EstablishExpandedDesignSpaceofPICA-D• Performarcjettestingandheatflux/pressureconditionsbeyondwhichPICAhaspreviouslybeentestedand/orflown
– PublishallPICA-DDataforcurrentandfuturemissions
InFY18/FY19,NASAAmesisleadinganeffortfundedbySMD-PSDtocharacterizeandextendthecapabilityofPICA-DtoEstablishLyocellPICAas
aDrop-InReplacementforHeritagePICA
2.EstablishmentofPICA-DasaReplacementforHeritagePICA• InFY17,SMD-PSDfundedARCtomanufactureandperformlimitedpropertyand
aerothermalcharacterizationofLyocell-basedPICA– FY17tasksuccessfullycompletedlimitedtestingthatindicatedtheviabilityofPICA-Dasa
potentialreplacementforheritagePICA
MaterialPropertyCharacterization• InFY17,3billetsofPICA-Dweremanufacturedtosupporttesting– LimitedIn-plane(IP)tension,through-thickness(TT)tension,andthroughthicknessthermal
conductivityat100Fand350FwereconductedandcomparedtoheritagerayonPICA
• OveralltheseresultsareinfamilywithproductionrayonPICA– howeveradditionaltestingisneededasonlyafewcouponswereevaluated– Limitedpropertydatahadsubstantialscatter– detailedtestingplannedforFY18/19
3.EstablishmentofPICA-DExpandedCapability• 9billetsofFiberFormweremanufacturedinFY17tooptimizetheprocessusing
Lyocellfibers– BilletsspannedthespecdensityrangeandbilletFiberFormtargetdensitieswereachieved
• Developmentandfabricationof30.8-mnet-shapedFiberFormheatshieldblank(OSIRISREx scale)werealsocompletedinFY17– Densitytargetsinall3netcastblankswereachieved
• Processrefinementsandlessonslearnedhavebeendocumented
• LimitedNonDestructiveEvaluation(NDE)completedontheLyocellnearnetshapeFiberFormunittoevaluatefiberalignmentandcheckforoff-nominalfeatures
• FY18/19workwillexpandontheworkperformedinFY17anddemonstraterepeatabilityaswellasincreasesinglepiecenetcastdimensionsto>1.2-m
ArcJetCharacterization
MaterialAveragecenterline
recession (1550W/cm2
and1.3atm)
Averagecenterlinerecession (400W/cm2
and0.3atm)
Averagecenterlinerecession (220W/cm2
and0.08atm)
LyocellDerivedPICA 4.0mm 6.02mm 3.79mm
RayonDerivedPICA 4.2mm 5.97mm 3.89mm
RayonDerivedPICA LyocellDerivedPICA
Posttest Posttest
Pretest Pretest LyocellDerivedPICARayonDerivedPICA
Examplein-depthTCTrace@1550W/cm2
RecessionComparison
• 3arcjetconditionsweretestedinFY17- NFproposersprovidedguidanceontestconditions- AllconditionswillberepeatedinFY18/19todemonstratedatarepeatability
Foragiventestcondition(sameruntime)initialresultsindicatethatrecessionandin-depthtemperaturebetweenaLyocellderivedPICAand
aheritagerayon-derivedPICAarecomparable
• NASAARCisworkingwithSMD-PSDtoaddressPICArayonsustainabilityconcerns
• InFY16/17,LyocellBasedPICA(PICA-D)wasmanufacturedandlimitedtestingperformedshowingittobeagoodcandidateasapotentialreplacementforheritagerayon
• EstablishingPICA-Dasa“dropinreplacement”willallowmissionstodependonanddesignmissionswithPICAwithoutanyrisktypicalofareplacement.
• EstablishingtheextendedcapabilityofPICA-DwillallowSampleReturnMissionswithhigherentryspeedthatwerenotconsideredbefore.
6.Summary
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0 0.2 0.4 0.6 0.8 1 1.2 1.4
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argi
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Stag Pressure, atm
Arcjet Test ConditionsDragonflyCommet Sample ReturnStardust
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