3D打印英文文献+翻译.docx
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3D打印英文文献+翻译.docx
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3D打印英文文献+翻译
JournaloftheEuropeanCeramicSociety31(2011)2543–2550
Inkjetprintingceramics:
Fromdropstosolid
B.DerbySchoolofMaterials,UniversityofManchester,OxfordRoad,ManchesterM139PL,UKAvailableonline16February2011
Abstract
Inkjetprintingisapowerfulmicrofabricationtoolthathasbeenappliedtothemanufactureofceramiccomponents.Tosuccessfullyfabricateceramicobjectsanumberofconditionsmustbesatisfiedconcerningfluidpropertiesanddropplacementaccuracy.Ithasbeenproposedthatfluidsareprintablewithinthebounds1 Keywords: Inkjetprinting;Shaping;Drying;Suspensions 1.Introduction Inkjetprintinghasmajorcommercialapplicationsingraph-icsoutputandotherconventionalprintingoperations.However,therehasbeendevelopinginterestinusinginkjetprintingtomanufacturecomponentswithapplicationsfor: displays,1plas-ticelectronics,2rapidprototyping,3tissueengineering,4andceramiccomponentmanufacture.5Asignificantandfundamen-taldifferencebetweenthesenewapplicationsandthemorewidespreadapplicationofprintingtextorimagesisthebehaiouroftheprintedinkdropletsontheprintedsubstrate.Mostimagesareconstructedbythedepositionofdiscretedropletsand,inordertooptimiseresolutionandcontrast,thesedropletsareiso-latedanddonotcontacteachother.Incontrast,manyofthenewapplicationsforinkjetprintingenvisagethemanufactureofcontinuous1-,2-,or3-dimensionalstructures(1-,2-,or3-D).Suchstructuresrequireacontinuousdistributionofmaterialandthisnecessitatescontactandadhesionbetweenindividualdropsafterprinting.Inkjetprintingconstructsobjectsbytheprecisionplacementofpicolitrevolumesofliquidandthustheinitialinterac-tionbetweenprintedmaterialandasubstrateisaliquid/solidinteraction.Ultimately,theprinteddepositundergoesasolid-ificationprocessthatcanoccurthroughsolventevaporation, temperatureinducedsolidification/gelationorchemicalreac-tion.Considerationsoftherelativetimescalesofdropspreadingandsolidificationindicatethattherewillbeasignificantperiodoftimeafterprintingwhenaliquidispresentonasurface6andthusthemorphologicalstabilityofcoallescingliquidfilmsmustbeexamined,asmusttheeffectsofthesolidificationprocess. Therehasbeenaconsiderablenumberofpublicationsontheuseofinkjetprintinginthemanufactureofceramics.7–17Thesepriorstudieshaveusedallinkjetdropgenerationtechnologies(continuous,thermaldrop-on-demandandpiezoelectricdrop-on-demand)tosuccessfullyproduceceramicobjectsusingbothsolventevaporationandphase-changesolidification.Industrialinkjetprintingtechnologynowusespiezoelectricdrop-on-demand(DOD)generationtechnologyandthisisthechosenmethodformostapplicationsinprintingfunctionalmaterials.Thephysicaloperationofthesedifferentprintingtechnologies andthereasonsforthechoiceofpiezoelectricDODprintinghavebeendiscussedindetailelsewhere6,18;henceherewewill confineourconsiderationstothistechnology.Wewillalsoonlyconsidertheprintingofceramicinksthatsolidifythroughsol-ventevaporation.Despiteearlierworkdemonstratingthatitispossibletosuccessfullyprintcmscaleobjectsusingawaxbasedphasechangeceramicink,11–13ceramicinkscontainrelativelylowvolumefractionsofsolidandthusthereisconsiderableshrinkageandpotentialfordistortionduringdewaxingandsintering.14 Inordertofabricateceramicobjectsusinginkjetprinting,itisnecessarytosatisfyanumberofrequirements.Firstthereis aneedtoproducestableceramicsuspensionswithdefinedfluidpropertiessuchthattheycanbepassedthroughadropletgener-atorandformregulardrops.Second,thesesuspensionsneedtobedeliveredontoasubstrateorontoapreviouslyprintedlayerofsolidifiedceramicink,withdropsinsufficientproximitytoeachothertoallowthemtointeractandformdesired2-Dfeatures.Next,theprintedceramicinkmustundergophasetransitiontoasoliddeposit.Finally,toproduce3-Dstructuresthedeposi-tionanddrying/solidificationprocessesneedtoberepeatedonalayerofpre-depositedanddriedmaterial.Herewewillconsidereachoftheserequirementsandtheiroptimizationforthedirectprintingofceramics. 2.Ceramicinks ManufacturersofDODinkjetprintingequipmentnormallystatearangeofviscosityandsurfacetensionwithinwhichinksmaybesuccessfullyprinted.However,thisinformationisnor-mallyprovidedforthebenefitofformulatinggraphicsinksandmaynotbedirectlyapplicabletothedevelopmentofceramicinks.Thisisbecauseinkscontainingasignificantvolumefrac-tionofceramicparticlesinsuspensionhavemuchhigherdensityvaluesthantypicalgraphicsinks,whichtypicallyhavedensitiesintherange800–1000kgm−3andthebehaviourofafluidduringprintingdependsstronglyonitsinertialbehaviour. Thefluidrheologicalrequirementsforaprintableinkaredeterminedbythephysicsandfluidmechanicsofthedropgen-erationprocess.6,18ThebehaviouroffluidsduringinkjetprintingcanberepresentedbytheReynolds,WeberandOhnesorgenum-bers(Re,We,Oh): Re=vρa,(1a) η We=v2ρa(1b) γ √η Oh=We=(1c) Re(γρa)1/2 whereρ,ηandγarethedensity,dynamicviscosityandsurfacetensionofthefluidrespectively,visthevelocityandaisacharacteristiclength.FrommidentifiedtheOhnesorgenumber,Oh,astheappro-priategroupingofphysicalconstantstocharacterisedropgenerationinaninkjetprinter.19Ohisindependentoffluidvelocityandiscommonlyusedinanalysesdescribingthebehaviourofliquiddrops.However,inFromm’spublication,hedefinedtheparameterZ=1/Ohandfromasimplemodeloffluidflowinadropgeneratorofsimplifiedgeometry,hepro-posedthatZ>2forstabledropgeneration.19Reisextendedthisthroughnumericalsimulationandproposedthefollowingrange,10>Z>1,forstabledropformation.20IfZ<1,viscousdissipa-tionpreventsdropejectionfromtheprinterandifZ>10,dropletsareaccompaniedbyunwantedsatellitedrops.Jangetal.studiedtheDODprintabilityofanumberoffluidmixturesofethanol,waterandethyleneglycol.ThroughthistheyexploredarangeofvaluesofOhanddeterminedthattherangeofprintabilitywas Fig.1.Fromm’sparameterZ(Z=1/Oh)influencestheprintabilityoffluids.DashedlinesidentifythelimitsforprintabilityproposedbyReisetal.20Experi-mentalpointsareplottedforanumberofceramicsuspensions/inks: greysymbolsindicatesuccessfulinkjetprinting,blacksymbolsindicatethatnodropswereformed,andwhitesymbolsindicatethepresenceofsatellitedropsalongwiththemainprinteddrop. 4 Thereisnowasubstantialbodyofliteraturedescribingtheinkjetprintingofanumberofceramicsuspensionsandotherfluidsfornon-graphicsapplications;unfortunatelynotallpublicationsreportsufficientinformationontherheologi-calpropertiesoftheceramicsuspensionstotestthisproposedcriterionforprintabilityinallcases.Fig.1presentssuchdatathateitherreportedthevalueofOh(orZ)orreportedsufficientdatathatitiseasilycalculated.TheverticaldashedlinesonthefigureatOh=1andOh=10representthelimitsforstableinkjetprintingcalculatedbyReis.20Theexperimentaldataispresentedfromeightfluidsystemswithagreysymbolindicat-ingthesuccessfulprintingofindividualdrops,ablacksymbolindicatesthatfluidswiththesepropertiescouldnotbeprinted,andfinallyawhitesymbolshowsthecaseswhereafluiddropwassuccessfullyejectedbutaccompaniedbyoneormoresatel-litedrops.Itisusefultoseparatethesedataintotwosets: fluidsystems1–6weredeliveredusingpiezoelectricDODprinters,whilefluidsystems7and8weredeliveredusingathermalDODprinter.ThedataobtainedfromexperimentsusingpiezoelectricDODprintingshowsreasonablygoodagreementwithReis’smodel,howeverthatobtainedintheonestudyusingathermalDODprintershowsverypooragreement,17atleastwiththeupperboundforthepredictionoftheonsetofsatellitedropfor-mation.ÖzkolconsideredthatonereasonforthediscrepancybetweenReis’spredictionandtheirresultscouldbethediffer-enceinactuationbetweenpiezoelectricandthermalDODinkjetdropletgenerators.17 Thehypothesisthatchangesinactuationexplainthedif-ferentbehaviourobservedbetweenthermalandpiezoelectricDODinkjetprintingissupportedbyanexperimentalstudyofdropandsatelliteformationinapiezoelectricDODprinterbyDongetal.22Theyfoundthatthedropformationmechanismandtheconditionsunderwhichagivenfluidformedsatellitesisalsocontrolledbytheshapeandamplitudeofthedriving pulseappliedtothepiezoelectricactuator.Thedrivingpulse inDODprintingisalsoknowntocontrolboththesizeoftheejecteddropanditsvelocity.12,22,23Reisdemonstratedthatfor theformationofdropsusinghighlyloadedceramicsuspensions,acousticphenomenaareimportantandthattherearem
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