www.flexitallicsofc.com

Sealing materials forSolid Oxide Fuel Cells.

THERMICULITE866 / 866 LS

®

Thermiculite® 866 - The proven sealingmaterial for Solid OxideFuel Cell applications.

THERMICULITE®866

Thermiculite® 866 is a sealing materialspecifically designed as a compression sealfor Solid Oxide Fuel Cells [SOFC]. It is provingto be very successful in a range of SOFCapplications around the world.

Thermiculite® 866 is a product utilising theThermiculite® technology, based upon theuse of chemically exfoliated vermiculite, that has been developed by Flexitallic toproduce a range of high performance, hightemperature, patented, sealing materials for industrial sealing.

Vermiculite, a naturally occurring mineral isclosely related to mica, a mineral noted forhigh temperature capability, high chemicalresistance and an electrical insulation. Both mica and vermiculite occur naturally as flakes which consist of a stack of verymany crystal plates where each crystal plate is nanometres thick. Those flakes ofvermiculite, unlike those of mica, are able to be exfoliated so that the crystal platesseparate from each other.

This exfoliation can be partly achieved by theapplication of heat, the result is then thewell known form of vermiculite used in manyeveryday applications such as in gardeningcompost, as a thermal insulation material,as a packaging material and in fireprevention applications. However, the very thin crystal plates can be separatedefficiently from each other by chemicalmeans to produce a form which consists of just these very thin crystal plates. Theseparated plates are highly flexible and havethe most useful property of adhering to eachother to produce a thin, flexible, film. If asecond material is added to the chemicallyexfoliated vermiculite then the secondmaterial will be bound by the chemicallyexfoliated vermiculite without the need forthe addition of a binder. This binding actionof chemically exfoliated vermiculite meansthat when it is mixed with other, morphologycompatible, materials that it is possible tomake, by methods developed by Flexitallic, a very flexible sheet material. This sheetmaterial, Thermiculite® 866, is readily cutinto gaskets of complex shapes.

Structure of Thermiculite® 866

THERMICULITE® 866THE PROVEN SEALING MATERIAL FOR SOFC APPLICATIONS

Stable to high temperaturesup to 1000oC

No organic fillermaterial

Soft and compressible

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 thata seal is created and then the seal is maintained in service

• No burn off of organic material at elevated temperature

• No reduction in gasket thickness at elevated temperature

• Sealing performance not reducedby thermal cycling

THERMICULITE® 866 LS• Sealing achieved at very lowsurface stresses

• Extremely high level of sealingefficiency achieved

• Sealing performance not reducedby thermal cycling

• Sealing coating compensates for irregularities in surfaces to be sealed

• Gasket cutting just as easy for Thermiculite® 866

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Thermiculite® 866 cut gasket samplesCrystal plates: Each crystal plate is nanometres thick

0.4

0.3

0.2

0.1

00 100 200 300 400 500 600 700

Leak rate (ml/min/m)

THE ROBUSTNESS AND SEALING PERFORMANCEOF THERMICULITE® 866 & THERMICULITE® 866 LS

Robustness Against Thermal Cycling

Gasket Stress 0.1 MPa

Thermiculite® 866 LS

4.0

3.0

2.0

1.0

00 100 200 300 400 500 600 700Le

ak rate (ml/min/m)

Time / h

p = 25 mBar

3.500

3.000

2.500

2.000

1.500

1.000

0.500

0.0000 5 10 15 20 25 30

Leakage rate (ml/min/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 development of Thermiculite® 866

The components of Thermiculite®

866 ensure that a seal is createdand then maintained in service.Consisting of highly alignedplatelets of chemically exfoliatedvermiculite binding other uniquekey ingredients Thermiculite® 866is very soft, resulting in acompressible and flexible materialthat is completely free of organiccontent.

Due to its unique chemical andphysical properties, Thermiculite®

866 is highly temperature resistant(1000°C) and, as there is noorganic content, there is no burnoff of volatile components at SOFCoperational temperatures.

This ensures that during thelifetime of the fuel cell there is no increase in porosity and noadditional leakage at elevatedtemperature. Figures 1 and 2 showthat there is no difference insealing performance at elevatedtemperature.

As there is no burn off of organicmaterial at elevated temperature there is also no reduction in thegasket thickness at temperatureand no resulting relaxation of thebolts.The seal is therefore stableduring cycling between ambientand operational temperatures.

Thermiculite® 866 providesexcellent service performance.Figures 3 and 4 show stack resultsobtained by a customer andreproduced with their fullpermission.

Leak rate (ml/min/cm)

SEALING CURVE FOR THERMICULITE® 866 OF 0.92mm‘AS MADE’ THICKNESS AT 600OC

Helium Pressure (bar)

0 1 2 3 4 5 6

0.04

0.03

0.02

0.01

0.00

Gasket Stress 20 MPaTemperature 600oC

Fuel leak (as % of fuel flow rate)

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

Leak rate (ml/min/cm)

SEALING CURVE FOR THERMICULITE® 866 OF 0.92mm‘AS MADE’ THICKNESS AT 25OC

Helium Pressure (bar)

0 1 2 3 4 5 6

0.04

0.03

0.02

0.01

0.00

Gasket Stress 20 MPaTemperature 25oC

1

2

3

Index of leak rate (%)

SOFC STACK SEALING WITH THERMICULITE® 866 REMAINS STABLEDURING 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

THERMICULITE®866 LS

5

6

7

Thermiculite® 866

Gasket Stress 0.1 MPa

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

Following development work at the VTT Technical Research Centreof Finland, see reference, Flexitallic has introduced Thermiculite®

866 LS using a further developed form of the coating to allow therange use of Thermiculite® 866 to be extended to those stackdesigns only offering a very low sealing stress. A minor amount ofglass powder is bound to each surface during the manufacturingprocess so that at the operational temperature of the SOFC cellThermiculite® 866 LS has a very thin coating of molten glass on each surface which seals the interfacial leakage paths.

No initial glass sintering cycle to above the operating temperature of the SOFC stack is required with Thermiculite 866 LS. Provided theservice temperature is at least 700oC the glass coating will form therequired seal.

When glass is used as the sole sealing material it is well known thatcracking of the seal with enhanced leakage results during thermalcycling. This is not the case with Thermiculite® 866 LS where thelevel of sealing is maintained during thermal cycling. Figures 6 and 7show, under the same conditions, the sealing performance ofThermiculite® 866 LS and Thermiculite® 866 respectively duringthermal cycles. Note scale differences of these figures.

UNITED KINGDOMFlexitallic LtdScandinavia MillHunsworth LaneCleckheatonWest YorkshireBD19 4LNUKTel. +44 1274 851273Fax. +44 1274 300303www.flexitallic.eu

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

CHINAFlexitallic SealingTechnology Co. LtdBuilding 3 SouthWujiang Export Processing Zone 688 Pangjin RoadWujiang, Jiangsu 215200P.R. CHINATel. +86 512 6303 2839Fax. +86 512 6303 2879www.china.flexitallic.com

FEBRU

ARY 2014.

Designed by Clear D

esign (Scotland) Ltd. E. info@

clearwebsite.co.uk

About The Flexitallic GroupThe Flexitallic Group is a global leader in specialisedsealing solutions and products serving the oil and gas,power generation, chemical and petrochemical industriesin emerging and developed markets. Focused on theupstream, downstream and power generation sectors, it has operations in France, the United States, Canada,Mexico, the United Kingdom, Germany, the United ArabEmirates, Saudi Arabia, Kazakhstan and China plus anetwork of worldwide licensing partners and distributors.www.theflexitallicgroup.com

CANADAAGS Flexitallic4340 - 78 AvenueEdmonton, Alberta, T6B 3J5CANADATel. +780 466 5050Fax. +780 465 1177www.agsflexitallic.com

UNITED ARAB EMIRATESFlexitallic LLC P.O. Box 6591Amenity CentreTower Number 210th Floor, Office 4Al Hamra Industrial AreaRas Al KhaimahUNITED ARAB EMIRATESTel. +971 (0)7 243 4305Fax. +971 (0)7 243 4306www.flexitallic.ae

SAUDI ARABIAFlexitallic Middle East LLCAl-Aujam Industrial City 6790-Al BadiaUnit No. 1Al Qatif 32656-2462KINGDOM OF SAUDI ARABIATel. +966 13 8089635Fax. +966 13 8089634www.flexitallic.sa

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