全尺寸电绝缘涂层的研制Fullscaleelectricalinsulationcoatingdev

FullscaleelectricalinsulationcoatingdevelopmentL.F.Moreschia,P.Rossia,*,M.Agostinia,S.Storaia,A.T.PeacockbaENEA,C.R.Brasimone,PB1,40032Camugnano(BO),ItalybEFDA-CloseSupportUnit,Boltzmannstrasse2,D-85748Garching,GermanyAbstractAde-mountablemechanicalsystemhasbeendesignedbyITER-ITfortheattachmentandtheremotehandlingoftheblanketmodules.Themodulesareattachedtothesupportingstructurebyboltingusingfourflexibleradialsupports(cartridges)whichareelectricallyinsulatedfromthevacuumvesseltoavoidhigh-valuecirculatingcurrents.Thehydrauliccoaxialconnectorsalsoelectricallyconnecttheblankettothemoduleandstrapsareusedtoprovideanelectricalpathforhalocurrents.Coatingthecontactsurfaceswithaluminaprovidestherequiredelectricalinsulation.TheobjectiveofthisworkwastotesttheperformanceoftheelectricalinsulationcoatingsspecifiedfortheITERblanketattachmentdesign.Thetestingcampaignrequiredthemanufactureofmock-upsandtheapplicationofaluminacoatingbyplasmaspraytechnique.Theflexibleattachmentsystemwasmechanicallytestedwitha500kNpush/pullloadfor1000cycles.Anotherassemblywasthermallycycledbetween150and3008Cfor1000timesininertgasatmosphereandthenmechanicallycycled.Theactivityincludedmechanicaltestingoftwopairsofwedgedcoatedkeysunderanimpactloadof500kNapplied1000times.Nofailuresanddamagesoccurredonthealuminacoatings,whichpreservedgoodinsulatingandmechanicalpropertiesconfirmingsuitabilityfortheITERblanketsystem.#2003ElsevierB.V.Allrightsreserved.Keywords:Blanketmodules;Aluminacoatings;Plasmaspraytechnique1.IntroductionTheobjectiveofthisactivitywastotesttheperformanceoftheelectricalinsulationcoatingsspecificallyforthede-mountablemechanicalsys-temfortheattachmentandtheremotehandlingoftheinternationalthermonuclearexperimentalre-actor(ITER)blanketmodules.Theactivityre-quiredthemanufactureofthemock-ups,theapplicationofaluminacoatingbyatmosphericplasmaspray(APS)techniqueandthefollowingtestingcampaignconsistedinmechanicalandthermaltestingofthemock-upsfortheconditionsapplicableinITER.Theactivityincludedalsoamechanicaltestoftwopairswedgedkeys,toverifythebehaviourofthealuminacoatingunderimpactloadcycling.2.Mock-upsdescriptionThealuminacoatingswereappliedonthecartridgeandonthecollaroftheflexibleattach-mentsystemandonthemechanicalkeys.*Correspondingauthor.Tel.:
/39-0534-801299;fax:
/39-0534-801225.E-mailaddress:[e-mail](P.Rossi).FusionEngineeringandDesign69(2003)303/307:10.1016/S0920-3796(03)00359-42.1.AluminacoatingTheuseofplasmaspraydepositiontechniquetoproduceceramiccoatingsoperatingaselectricalinsulatorshadalreadybeenstudiedanddevelopedbyENEAincollaborationwiththecompany‘‘Flametal’’inapreviouscontract[1].Theselectedcoatingforthepresentapplicationwaspurealumina(Al2O3)withathicknessof0.3mm.ThecoatingcharacteristicsandAPSsystempowderparametersarereportedinTable1.2.2.FlexibleattachmentsystemTheassemblyconsistedinanInconelstudboltscrewedinanAISI316LbaseandclosedbyaspecialnutwiththeinterpositionofaTi-alloycartridgeandaCu-alloycollar(Fig.1).Twoaluminacoatingswereappliedonthelowersurfacesofthecartridgeandonthelowersurfaceofthecollar(Fig.2).FourboltsweremanufacturedwithInconel718andthensubjectedtoasolutionanneal,followedbyadoublestageagetoprovideagoodcombina-tionofnotchrupturestrengthandductilitywithsufficienttensilestrengthofthematerial.TheTitaniumalloyusedforthecartridgeswastheTi/6Al/4VwhilethematerialselectedforthecollarwasCuAl11Fe4Ni5.Thespecialnut,manufacturedbySuperbolt,chosentotightentheassemblyandpreloadtheboltupto650kN,hasaringofsmallerboltsandawasher.Themainthreadservestopositionthetensionerontheboltagainstthehardenedwasherwhiletensioningisaccomplishedbytorquingthejack-boltsthatencirclethemainthread.2.3.MechanicalkeysThemechanicalkeyassemblyconsistedinasetoftwowedgedkeysscrewedonabaseplate,akeyprofileandaloadblock.ThealuminacoatingwasappliedonthekeysurfaceinterfacedtothebaseplatewhiletheoppositeinclinedsurfacewasTable1AluminacoatingcharacteristicsandsystempowderparametersAluminacoatingAl2O399%Otheroxides1%Grainsize5/25mmPorosity2/5%Bond:NiAl95%Ni/5%AlNiAlAl2O3SystempowderparametersCarriergasAr/H2Ar/H2Sprayrate55g/min48g/minSpraydistance140mm110mmFig.1.Flexibleattachmentsystemdrawing.Fig.2.Insulatedcartridgeandcollar.L.F.Moreschietal./FusionEngineeringandDesign69(2003)303/307304providedwithalowfrictioncoating.Thekeysweremadeofacopperalloy(CuCrZr)whileboththebaseplateandthekeyprofileweremadeofstainlesssteel(AISI316L).Eachkeywascon-nectedtothebaseplatewithacoupleofM6screws.Twopairsofmechanicalwedgedkeysweretested:thefirstonewithanangleofthewedgepartof1648(steepkeys)andthesecondonewithanangleof1728(smoothkeys).3.TestingcampaignTheexperimentaltestingcampaignstartedwiththemechanicaltestingoftheflexibleattachmentsystem.3.1.MechanicaltestingoftheflexibleattachmentsystemThemock-upwasassembledandpre-loadedbymeansofatorquemeterwrench.Thisoperationwasrepeatedseveraltimestoavoidanypossiblerelaxationofthematerials.Thepreloadingopera-tionconsis