2023年全國碩士研究生考試考研英語一試題真題（含答案詳解+作文范文）_第1頁
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1、Designation:D4745?14StardClassificationSystemBasisfSpecificationfFilledPolytetrafluoethlyene(PTFE)MoldingExtrusionMaterialsUsingASTMMethods1ThisstardisissuedunderthefixeddesignationD4745thenumberimmediatelyfollowingthede

2、signationindicatestheyearofiginaladoptioninthecaseofrevisiontheyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperepsilon()indicatesaneditialchangesincethelastrevisionreapproval.1.Scope1.1Thiss

3、tardclassificationsystembasisfspecificationcoverspolytetrafluoethylene(PTFE)filledmoldingcompoundsmadewithvirginPTFEresinsdefinedinSpecificationD4894asTypesIIIII.NOTE1—ThissystemcanbeusedasamodelfotherPTFEcompoundshaving

4、particulatefillersthatcansurvivethesinteringtemperaturesofPTFEascanthoselistedinthisstard.ThissystemisrestrictedtovirginPTFEbaseresinftechnicalreasons.Recycledreprocessedmaterialcannotbeprocessedsuccessfully.NOTE2—Thepro

5、pertiesmeasuredoncommerciallyfabricatedpartsmaydifferfromthelistedvaluesfsamplespreparedbytheproceduresgiveninthisspecificationdependingonpartgeometryprocessingparameters.1.2ThevaluesstatedinSIunitsaretoberegardedasstard

6、.1.3ThefollowingstatementappliestothetestmethodptionSection11ofthisspecification:Thisstarddoesnotpurpttoaddressallofthesafetyconcernsifanyassociatedwithitsuse.Itistheresponsibilityoftheuserofthisstardtoestablishappropria

7、tesafetyhealthpracticesdeterminetheapplicabilityofregulatylimitationspritouse.SeeNote5faspecificwarningstatement.NOTE3—ThereisnoknownISOequivalenttothisstard.2.ReferencedDocuments2.1ASTMStards:2D792TestMethodsfDensitySpe

8、cificGravity(RelativeDensity)ofPlasticsbyDisplacementD883TerminologyRelatingtoPlasticsD1600TerminologyfAbbreviatedTermsRelatingtoPlasticsD1708TestMethodfTensilePropertiesofPlasticsbyUseofMicrotensileSpecimensD3892Practic

9、efPackagingPackingofPlasticsD4894SpecificationfPolytetrafluoethylene(PTFE)GranularMoldingRamExtrusionMaterialsIEEEASTMSI10StardfUseoftheInternationalSystemofUnits(SI):TheModernMetricSystem33.Terminology3.1Definitions—The

10、terminologygiveninTerminologyD883isapplicabletothisspecificationunlessotherwisespecified.3.2DefinitionsofTermsSpecifictoThisStard:3.2.1bulkdensityn—themassinkilogramspercubicmetreofresincompoundmeasuredundertheconditions

11、ofthetest.3.2.2filledcompoundn—blendofPTFEresinasthematrixparticulatefillersgenerallyglassotheringanicmetallicpolymericmaterialsthatwithstthesinteringtemperatureofPTFE(327to380C).3.2.3freeflowresins(pelletized)n—generall

12、ymadebytreatmentoffinelydividedresinstoproducefreeflowingagglomerates.3.2.4lotn—oneproductionrun.3.2.5pigmentedcompoundn—acompoundinwhichapigmentisaddedfcolantpurposesonly.3.2.6stardflowresins(nonpelletized)n—finelydivid

13、edresinwithanaverageparticlesizelessthan100m.3.3Abbreviations—AbbreviationsareinaccdancewithTerminologyD1600.PTFEistheacronymfpolytetrafluoroethylene.4.Classification4.1ThisspecificationcoversthefollowingtwotypesofPTFEco

14、mpounds:4.1.1TypeI—Stardflowresins(nonpelletized)materialfgeneralpurposecompressionmolding.1ThisspecificationisunderthejurisdictionofASTMCommitteeD20onPlasticsisthedirectresponsibilityofSubcommitteeD20.15onThermoplasticM

15、aterials.CurrenteditionapprovedAug.12014.PublishedSeptember2014.iginallyapprovedin1991.Lastpreviouseditionapprovedin2012asD474511aε01.DOI:10.1520D474514.2FreferencedASTMstardsvisittheASTMwebsitewww.astm.gcontactASTMCusto

16、merServiceat.FAnnualBookofASTMStardsvolumeinfmationrefertothestard’sDocumentSummarypageontheASTMwebsite.3AvailablefromASTMInternationalHeadquarters100BarrHarbDriveWestConshohockenPA19428ASummaryofChangessectionappearsatt

17、heendofthisstardCopyright?ASTMInternational100BarrHarbDrivePOBoxC700WestConshohockenPA194282959.UnitedStates19.2.1TestBillet9.2.1.1Pritomoldingscreenthematerialthrougha2.0mmhsieveifnecessary.9.2.1.2Prefmsolidtestbilletsi

18、namold(seeFig.1)havingacrosssectionalareanotgreaterthan25.8cm2≤(4in.2)ofsufficientheighttocontainthesample.Endplugclearanceshallbesufficienttoensureescapeofentrappedairduringpressing.Amoldlengthof305to380mm(12to15in.)pro

19、ducesabilletapproximately50to75mm(2to3in.)long.Thebilletlengthshallnotexceed75mm(3in.).9.2.1.3Assemblethemold.Addtheresintothemold.thetopplugapplyhpressuremakingcertainthatthepusheriscenteredinthemold.Placethemoldinahydr

20、aulicpressremovethesupptringspacers.Increasetheloadingsmoothlytothefinalprefmingpressurein3to5min.Use20.7MPa(3000psi)fcompoundscontainingupto4%byweightfiller.Use34.5MPa(5000psi)fcompoundscontaining5to25%byweight68.9MPa(1

21、0000psi)fcompoundscontaining26%mefiller.Holdundermaximumpressuref2to5min.Openthepressremovethetoppusherfromthemoldfcetheprefmverticallyoutofthemoldusingacontinuoussmoothmovement.9.2.1.4Placetheprefminasinteringovensinter

22、inaccdancewiththeprocedureinTable4.9.2.1.5SectioningTestBillet:(1)Dividethetestbilletbyremovinga1.6mm(1?16in.)minimumfromoneendofthetestbilletpritopreparationofthetestspecimens.(2)Preparefivetestspecimens160.25mm(0.04060

23、.010in.)inthicknessfthedeterminationoftensilepropertiescutapieceofsuitablethicknessfspecificgravitymeasurements.Thispiecewillbeapproximatelycubicalinshapeweighingatleast10g.Allsurfacesmustbesmooth.Takecaretoavoidwedgesha

24、pecuts.9.2.2SpecificGravity(alternativemolding)9.2.2.1Pritomoldingscreenthematerialthrougha2.0mmhsieveifnecessary.9.2.2.2Acylindricalprefmingdie28.6mm(11?8in.)internaldiameterbyatleast76.2mm(3in.)deepthetestspecimenasagr

25、eedtoinX1.3isused.Endplugclearancesshallbesufficienttoensureescapeofairduringpressing.TABLE2TFECompoundsTypeIIFreeFlow(Pelletized)RawResinBulkDensitymingLMoldedParts(MoldedSintered)GradeSpecificGravityminSpecificGravitym

26、axTensileStrengthElongationmin%minMPaminpsi115%glassfiber6252.1502.2513.82000200225%glassfiber6252.1502.25012.41800150335%glassfiber6502.1502.2508.3120010045%glassfiber5%MoS25752.1502.30017.22500170515%glassfiber5%MoS260

27、02.1502.30013.81800120610%graphite6002.0702.19013.82000150715%graphite5502.1002.20010.3150060825%carbongraphite5001.9502.1008.3120020932%carbongraphite4001.9002.2006.91000201040%bronze7502.9503.25013.82000851160%bronze90

28、03.8004.00010.31500201255%bronze5%MoS29003.5004.0006.91000201350%stainlesssteel8503.2003.60013.820001000AsspecifiedbycustomersupplierAsspecifiedbycustomersupplier.TABLE3RequiredFillerContentMass%Tolerance%10to3124to25232

29、6to603461to755FIG.1PrefmingofPTFECompositeTestBilletTABLE4SinteringProceduresfTestBilletsInitialtemperatureC()AAmbientRateofheatingCh(Fh)605(1089)HoldtemperatureC(F)3706(69810)Holdtimemin2405RateofcoolingCh(Fh)605(1089)F

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