Manufacturability Demonstration And Assessment Of Aerogel Applicability As An Insulation Replacement For emmrtg Flight Module

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Rosamund Boyd
6 years ago
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Hlgate 1, Glenn Gaines 1, Rb Utz 1, Mihaela Niclau 1, Russell Bennett 1, Tm Hammel 1, Steven Keyser 1 Jng-Ai

1 Manufacturability Demnstratin And Assessment Of Aergel Applicability As An Insulatin Replacement Fr emmrtg Flight Mdule Ying Sng 1, Jshua Wjcik 1, Tim C. Hlgate 1, Glenn Gaines 1, Rb Utz 1, Mihaela Niclau 1, Russell Bennett 1, Tm Hammel 1, Steven Keyser 1 Jng-Ai Paik 2, Steve Jnes 2, and Thierry Caillat 2 1 Teledyne Energy Systems, Inc. (TESI), Hunt Valley, MD Jet Prpulsin Labratry, Pasadena, CA Albuquerque, NM February, 2015

2 Teledyne Advanced Pwer Technlgies Liquid Fueled TE systems 100 W MMRTG Curisity Rver 15 W Radiistpe TE systems Thermelectric systems fr space and terrestrial applicatins Fuel Cell Stacks Fuel cells fr space and terrestrial applicatins Stirling cnverter systems fr terrestrial cmbustin heated applicatins Fuel Cell Flight Systems Specialty Batteries Electrchemical energy strage Cmpact Passive FC Systems Stirling Cnverters (Persistent Pwer) FC Replacement fr Batteries Submersible Manned Vehicles Unmanned Navy Vehicles 2

Technlgy Transfer Prgram Enhanced Multi-Missin Radiistpe Thermelectric Generatr (emmrtg) Cncept Preserve all MMRTG envelpe, vlume, interfaces and munting

atmsphere) preserved 5-year develpment time SKD Thermelectric (TE) Cuples Substitutin f current MMRTG PbTe/TAGS cuples with skutterudite (SKD) cuples Sizing f

3 Technlgy Transfer Prgram Enhanced Multi-Missin Radiistpe Thermelectric Generatr (emmrtg) Cncept Preserve all MMRTG envelpe, vlume, interfaces and munting pints Offer significant increases in pwer >25% at beginning f life (BOL) >50% at end f 14-year missin (EOM) Multi-missin capability (vacuum and Mars atmsphere) preserved 5-year develpment time SKD Thermelectric (TE) Cuples Substitutin f current MMRTG PbTe/TAGS cuples with skutterudite (SKD) cuples Sizing f cuples t raise ht junctin temperature and increase efficiency Aergel Insulatin Technlgy transfer and further develpment Determine suitability fr use as TE mdule insulatin 3

4 Silica Aergel Applicatin fr emmrtg Exceptinally prus material presenting unique prperties High specific surface area Light weight Significant sublimatin suppressin ~5x10-7 g/cm 2. hr rate at 600 C achieved frm JPL s sublimatin 4000-hur life tests Excellent insulatin material Extremely lw thermal cnductivity Cmparable mechanical integrity Thermal stability at higher temperatures Ambiently dried aergels eliminate the super-critical drying prcess 4

5 Silica Aergel Develpment at TESI Wrked with JPL t transfer aergel insulatin technlgy Develp the capability t prduce aergel insulatin at TESI Measure the prperties deemed imprtant fr the insulatin surrunding thermelectrics in an RTG Determine if replacing sme, r all, f the current thermelectric mdule insulatin with aergel is feasible Successfully adapted JPL s advanced technlgy t synthesize silica aergels Further develped and ptimized the manufacturing prcess fr fabricating ambiently dried silica-based aergels Characterizing the aergel materials with the gal f further imprvements 5

existing cmmercial insulatins in the mdule In situ prductin using the cast-in

6 Synthesis f Ambiently Dried Aergel Ambient drying instead f supercritical drying prcess Mre practical and peratinally feasible Easily replace the existing cmmercial insulatins in the mdule In situ prductin using the cast-in ability withut expsing T/E materials t supercritical drying cnditins Lawrence Berkeley Lab 6

Manufacturability Demnstratin Baseline Aergel Radial Shrinkage Rate

0% High Aspect Rati Aergel Samples Unifrm aergel with crackfree bulk

Simulatin f Mdule insulatin Mdified aergels increase the mechanical

cuple leg gemetry n aergel frmatin and unifrmity was examined Chemical

7 Manufacturability Demnstratin Baseline Aergel Radial Shrinkage Rate Reduced frm 70.0% t 8.0% High Aspect Rati Aergel Samples Unifrm aergel with crackfree bulk structure Large Size f Aergel Sample with Dummy Cuples Encapsulated fr Simulatin f Mdule insulatin Mdified aergels increase the mechanical rbustness with further shrinkage rate reductin t nearly zer Effect f the cuple leg gemetry n aergel frmatin and unifrmity was examined Chemical cmpatibility f cuple materials t aergel gel precursr was investigated Demnstrated prductin capability fr multi-cuple mdule bulk insulatin 7

simplify curing and assembling Initial trials f 1/3 size f mdule insulatin Ready fr scale-up t

8 Cncept Mdule Design fr Aergel Direct casting-in technlgy eliminates additinal machining wrk f fragile insulatins Prper mld design may minimize the effect f skin layer in the mdule and simplify curing and assembling Initial trials f 1/3 size f mdule insulatin Ready fr scale-up t the full size f mdule insulatin Current mdule insulatin Cncept mld designed fr mdule size aergel insulatin 8

Hybrid Insulatin in Mdule Hybrid insulatin cmbines cmmercial mdule insulatin with aergel surrunding each SKD element Cmbining cmmercial and aergel materials tgether may prvide lw thermal cnductivity

9 Hybrid Insulatin in Mdule Hybrid insulatin cmbines cmmercial mdule insulatin with aergel surrunding each SKD element Cmbining cmmercial and aergel materials tgether may prvide lw thermal cnductivity with sublimatin suppressin demnstrated by aergel Initial trials f simply puring the gel precursr int the hles in the cmmercial insulatin was successful Additinal experiments will be perfrmed Aergel Cmmercial Insulatin SKD Elements Investigate particle size and distributin f pwders in the gel precursr Investigate pre size and distributin f the dry aergel Evaluate the reinfrcement materials and ptimize mixing prcess Determine if a thin cating can be applied n the surface f the cmmercial mdule insulatin that is in cntact with aergel precursr as barrier If aergel is nt suitable as a bulk insulatin, hybrid ptin prvides a path frward 9

10 Assessment f Aergel Applicability Evaluatin Criteria Established Appearance Unifrm structure with n significant defects such as cracks r vids Thermal cnductivity N higher than existing insulatin under the perating cnditins as mdule bulk insulatin Thermal stability Structural integrity with minimal shrinkage and weight lss after expsure t the perating temperature Mechanical Strength Cmpressive strength cmparable t the existing insulatin Ability t stand up t dynamic lads Material cmpatibility Minimal r n reactin between the aergel precursr and the cuple cmpnents Capability fr Characterizatin at TESI Laser flash system fr thermal diffusivity and mdulated DSC fr heat capacity TGA/DSC fr thermal stability and phase transitin study High temperature vacuum ven and ht press fr thermal stability test SEM/EDS and FT-IR fr micrstructure and cmpsitin analysis BET fr surface area and pre size distributin and particle analyzer fr particle size and distributin Cuple/mdule life testers and vibratin test instrument Cllabratin with ther labs fr additinal analysis 10

Density, mg/cm 3 Pure Silica Aergel 180-200

11 Aergel Basic Physical Prperties Aergel Density and Cmparisn t Cmmercials Sample Density, mg/cm 3 Pure Silica Aergel Mdified Aergel Cmmercial Insulatin Cmmercial Insulatin Hydrphbicity Micrstructure f Aergels FT-IR Spectra f Aergels 11

12 Thermal Stability Aergel had little shrinkage (<1%) and a weight lss f 8.5% as temperature increased frm RT t 600 C under vacuum and remained stable in dimensin and a weight lss f 2.1% at 600 C in 50 hurs, cmparable t the cmmercial insulatin material There were n cracks r ther defects bserved during testing N bvius change in micrstructure bserved under micrscpe 12

Mechanical Strength Mechanical strength is anther imprtant prperty t be addressed fr characterizing aergel materials as alternatives t the

with flat, parallel faces perpendicular t the lng axis were prepared fr testing Cmmercial insulatins were tested fr cmparisn Initial test

13 Mechanical Strength Mechanical strength is anther imprtant prperty t be addressed fr characterizing aergel materials as alternatives t the cmmercial insulatins Cmpressin Test Test methdlgy fr cmpressin testing f the aergel samples was develped High aspect rati cylindrical samples with flat, parallel faces perpendicular t the lng axis were prepared fr testing Cmmercial insulatins were tested fr cmparisn Initial test results revealed a relatively lwer cmpressive strength and elastic mdulus Additinal samples were prepared with the reinfrcement materials fr higher cmpressive strength. Being tested Vibratin Test Small scale Sinusidal vibratin sweep t identify resnance frequency and run sinusidal vibratin test at resnance frequencies Large scale Test lad prfile MMRTG vibratin envirnment Further mdificatin wrk fr imprving mechanical rbustness 13

Thermal Cnductivity Sample preparatin, test cnditins and methdlgy successfully develped and ptimized fr measurement f thermal diffusivity

Initial results shwed aergel had a relatively higher thermal cnductivity than the cmmercial insulatin but is still prmising as replacement

14 Thermal Cnductivity Sample preparatin, test cnditins and methdlgy successfully develped and ptimized fr measurement f thermal diffusivity and specific heat capacity f aergel samples using laser flash system and DSC at TESI Testing cnditins: rm temperature t 700 C in argn Initial results shwed aergel had a relatively higher thermal cnductivity than the cmmercial insulatin but is still prmising as replacement insulatin in the mdule Further wrk t mdify the structure and cmpsitin fr lwering thermal cnductivity t imprve perfrmance if used as bulk insulatin 14

15 Summary and Future Plan Cmprehensive develpment f synthesis, structure, thermal prperties and characterizatin f silica aergel has been dne. Manufacturing capability has been successfully demnstrated. TESI can prduced ambiently dried aergels cnsistently t meet mdule size insulatin requirements Prcess details were refined and test criteria were established fr characterizing and mdifying aergel materials Crack-free and nearly zer shrinkage rate after ambient drying prcess Excellent thermal stability at the mdule perating temperature Superhydrphbic surface even after expsure t 600 C Current and future wrk Hybrid insulatin Reinfrced aergel Finalizatin f mld design Scale-up t mdule size Dynamic lad test 15

Cntact Infrmatin Teledyne Energy Systems, Inc. Ying Sng Ying.sng@teledyne.

16 Cntact Infrmatin Teledyne Energy Systems, Inc. Ying Sng Gilry Rad Hunt Valley, MD Phne Fax 16

The moisture susceptibility of a mixture is determined based on the combined effect of material properties as well as mixture properties.

The moisture susceptibility of a mixture is determined based on the combined effect of material properties as well as mixture properties. Asphalt Research Cnsrtium Misture Damage Hypthesis The misture susceptibility f a mixture is determined based n the cmbined effect f material prperties as well as mixture prperties. Material prperties