www.flexitallic.eu

Sealing materials forSolid Oxide Fuel Cells.

THERMICULITE®

Proven sealing materialsfor Solid Oxide Fuel Cells.

THERMICULITE®

By exploiting these properties, Flexitallic has developed a process to produce a verycompressible, flexible sheet sealing materialwith very tightly controlled thickness anddensity. The resulting sheet material can beeasily cut into gaskets with complex shapesincluding those with narrow land widths(≥4mm). The controllable manufacturingapproach means sheet material can be produced in a range of thicknesses to suitdifferent designs.

Thermiculite® ensures that a seal can becreated and then maintained in service.Thermiculite® 866 is soft, resulting in acompressible and flexible material that is completely free of organic content.

Due to its unique chemical and physicalproperties, TH866 and TH870 are both highlytemperature resistant (1000°C) and, as there is no organic content, there is no burn off of volatile components at SOFC operationaltemperatures. It also means that the sensitivecell chemistry is not poisoned.

At elevated temperature there is also noreduction in the gasket thickness and noresulting relaxation of the bolts. The seal is therefore stable during cycling between ambient and operational temperatures.

Thermiculite® 866 provides excellent serviceperformance. Figures 3 and 4 show stack results obtained by a customer and reproduced with their full permission.

Structure of Thermiculite® 866

THERMICULITE® 866 and 870THE PROVEN SEALING MATERIAL FOR SOFC APPLICATIONS

Stable to high temperaturesup to 1000oC

No organicfiller material

Soft andcompressible

Currently operatingin service units

No thermal degradationof the seal at SOFC

operating temperatures

Excellent seal integritymaintained

Easily cut into complexshapes and profiles

Case studies providingthe benefits of

Thermiculite® 866

Extended lifetimeperformance

Material does not become porousover time or suffer a gasket

thickness reduction

Complex sealing arrangementsare easily accommodated

Many reports of very lowleakage rates even through

many thermal cycles

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THERMICULITE® 866• Thermiculite® 866 is recognised asthe material of choice to achievehigh sealing efficiency by leadingdevelopers of SOFC technology

• Thermiculite® 866 ensures that a seal is created and thenmaintained in service

• No burn off of organic material at elevated temperature

• No reduction in gasket thicknessat elevated temperature

• Sealing performance not reduced by thermal cycling

THERMICULITE® 870• Sealing achieved at very lowsurface stresses

• Very high compressibility

• Sealing performance not reduced by thermal cycling

• Gasket cutting just as easyfor Thermiculite® 866

www.flexitallicsofc.com Front cover image: Thermiculite 866 cut gasket samples

Crystal plates: Each crystal plate is nanometres thick

Thermiculite® 866 and 870 are sealing materialsspecifically designed for use as compressionseals for Solid Oxide Fuel Cells (SOFC) and SolidOxide Electrolysers (SOE). They have been usedvery successfully in a range of SOFC applicationsaround the world.

TH866 and TH870 utilise the unique properties of Thermiculite® technology, based upon the use of chemically exfoliated vermiculite,developed by Flexitallic to produce a range ofhigh performance, high temperature resistant,patented sealing materials for industrialapplications.

Vermiculite is a naturally occurring mineralnoted for its high temperature capability, widechemical resistance and electrical insulationproperties. Vermiculite occurs naturally as flakeswhich consist of a stack of very many crystalplates where each crystal plate is nanometresthick. These flakes are able to be exfoliated sothat the crystal plates separate from each other.

Partial exfoliation can be achieved by theapplication of heat, resulting in a coarseexpanded form of vermiculite however thecrystal layers can also be separated efficientlyfrom each other by chemical means whichproduces a form which consists of just thesevery thin, high aspect ratio crystal plates. The separated plates are highly flexible andhave the useful property of adhering to eachother to produce a thin, flexible film. The selfbinding nature of the vermiculite meansadditional compounds can be added without the need for a supplementary binder.

3.500

3.000

2.500

2.000

1.500

1.000

0.500

0.0000 5 10 15 20 25 30

Leak

age

rate

(ml/m

in/m

)

0 5 10 15 20

125

100

75

50

25

0

Fuel

1

0.8

0.6

0.4

0.2

0

Pressure (bar)

0 0.2 0.4 0.6 0.8 1 1.2 1.4

Achieved atoperationaltemperatureroom temperature

operational temperature

Initial target

Achieved at ambienttemperature

Advanced test equipment aided Flexitallic’s developmentof Thermiculite® 866

Fuel

leak

(as

% o

f fue

l flo

w ra

te)

SOFC STACK SEALING PERFORMANCE ACHIEVED WITHTHERMICULITE® 866 COMPARED WITH INITIAL PROJECT TARGET3

Inde

x of

leak

rate

(%)

SOFC STACK SEALING WITH THERMICULITE® 866 REMAINS STABLE DURING THERMAL CYCLING TO OPERATIONAL TEMPERATURE

Thermal Cycles

4

Air

Pressure (mbar)

COMPARISON OF SEALING OF THERMICULITE® 866 &THERMICULITE® 866 LSAS A FUNCTION OF GAS PRESSURE AND GASKET STRESS

UncoatedCoated0.1 MPa0.4 MPa

X

X X X X X X X X X X X X X X X X X X X X X X X X X XX X X X X X X X X X X X X X X X X X X X X X X X X X

5

Reference: M. Rautanen et al, J. Power Sources 247 (2014) 243-248

For some SOFC designs a softer, more compressiblesealing material is required. As a result of thisrequirement, Flexitallic developed Thermiculite®

870, building upon the knowledge and experiencegained from TH866. TH870 is significantly morecompressible under low loads, e.g. 1MPa. TH870 is around ten times more compressible than TH866.

Figure 1 shows load vs defection for TH870compared to TH866. At a stress of 1 MPa TH870compresses 0.22mm whereas TH866 gasket onlycompresses 0.02mm under the same load.

Thermiculite® 870 also seals at a comparable level to TH866, but at much lower applied loads.This is the case at ambient and elevatedtemperatures. Figure 2 shows an 80 hour leakagetest at ambient temperature.

For more information see Introduction of a LowSealing Stress Vermiculite Based CompressionGasket for SOFCs; S Bond & S Shaw, ECS Trans.2018 83(1): 159-170.

LS COATINGThermiculite® 866 can be offered with an additional glass based surfacecoating. This material is known asTH866LS. A thin coating of glasspowder is bound to each surface of thesheet during the manufacturing processso that at the operational temperature ofthe SOFC cell the coating melts thereforereducing the interfacial leakage paths.

No initial glass sintering cycle to above the operating temperature of the SOFC stack is required with Thermiculite® 866LS. Provided the service temperature isat least 700°C the glass coating willform the required seal.

Please note 866LS has now beensuperseded by TH870 material.

Compression Thickness (mm)

Gask

et S

tress

(MPa

)

6

5

4

3

2

1

00 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2 0.22 0.24 0.26 0.28 0.3 0.32 0.34 0.36

TH870TH866

Time (hours)

Leak

age

(ml/m

in/m

)

6

5

4

3

2

1

00 10 20 30 40 50 60 70 80 90

TH866 0.5mmTH870 0.7mmTH870 1.0mm

COMPRESSION OF TH870 AND TH866 GASKETS1

AMBIENT SEALING PERFORMANCE. SURFACE STRESS 3MPa, HELIUM PRESSURE 100 mbar2

JUNE2018–REV3

Desi

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www.flexitallic.eu

About The Flexitallic GroupThe Flexitallic Group is a global leader in specialised sealing solutions and products serving the oil and gas, powergeneration, chemical and petrochemical industries in emergingand developed markets. Focused on the upstream, downstreamand power generation sectors, it has operations in France, theUnited States, Canada, Mexico, the United Kingdom, Germany,Belgium, the United Arab Emirates, Kazakhstan and China plus a network of worldwide licensing partners and distributors.www.theflexitallicgroup.com

KAZAKHSTANNovus Sealing Caspian LLPa Flexitallic Joint Venture7v Atambayev St.Atyrau 060005REPUBLIC oF KAZAKHSTANTel: +7 7122 309936Fax: +7 7122 309937www.novussealingcaspian.com

FRANCESiem Supranite a Flexitallic Company31-33 Rue de Mogador75009 ParisFRANCETel. +33 (0)1 48 88 88 88Fax. +33 (0)1 47 66 88 44www.siem.fr

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Scandinavia MillHunsworth LaneCleckheatonWest Yorkshire, BD19 4LNUKTel. +44 1274 851273Fax. +44 1274 300303www.flexitallic.eu

Branches also in Aberdeen,Middlesbrough, EllesmerePort and Cardiff.

CANADAFlexitallic Canada Ltd

4340 - 78 AvenueEdmonton Alberta, T6B 3J5CANADATel. +780 466 5050Fax. +780 465 1177www.flexitallic.ca

SINGAPOREFlexitallic Ltd Singapore BranchLevel 42 Suntec Tower Three8 Temasek BoulevardSINGAPoRE038988Tel: +65 68663638www.flexitallic.eu

BELGIUMFlexitallic Belgium bvba

De Wolkammerij,Adolf Greinerstraat 122660 AntwerpBELGIUMT: 32 (0) 3 740 50 45www.flexitallic.be

UNITED STATESFlexitallic US LLC

6915 Highway 225Deer ParkTexas 77536 USA Tel. +1 281 604 2400Fax. +1 281 604 2415www.flexitallic.com

UNITED ARAB EMIRATESFlexitallic LLC Plot 108, Road EAl Hamra Industrial AreaRas Al KhaimahUNITED ARAB EMIRATESTel. +971 (0)7 243 4305Fax. +971 (0)7 243 4306www.flexitallic.ae

GERMANYFlexitallic GmbH

Halskestr. 4a47877 WillichGERMANYTel: +49 (0) 2154 95363-0Fax: +49 (0) 2154 95363-29www.flexitallic-gmbh.de

CHINAFlexitallic Gasket Technology(Suzhou) Co., Ltd

Building A, 1868 Guangming RdTechnological Development ZoneWuJiang Economic 215200CHINA Tel. +86 512 6303 2839Fax. +86 512 6303 2879www.china.flexitallic.com

UNITED STATESCustom Rubber Products

2625 BenningtonHoustonTexas 77093USATel. +1 713 691 2211Fax. +1 713 691 3005www.customrubber.com