作者:标准资料网 时间:2024-05-10 20:10:23   浏览:8510   来源:标准资料网

【英文标准名称】:StandardTestMethodforNormalSpectralEmittanceatElevatedTemperatures
【原文标准名称】:升高温度时标准光谱发射的标准试验方法
【标准号】:ASTME307-1972(2008)
【标准状态】:现行
【国别】:美国
【发布日期】:1972
【实施或试行日期】:
【发布单位】:美国材料与试验协会(US-ASTM)
【起草单位】:E21.04
【标准类型】:(TestMethod)
【标准水平】:()
【中文主题词】:
【英文主题词】:emittance;infraredemittance;materialradiativeproperty;radiativeheattransfer;spacecraftthermalcontrol;spectralnormalemittance;thermalradiation;Emittance;Infrared(IR)analysis--aerospacematerials/applications;Infraredspectroscopy
【摘要】:Thesignificantfeaturesaretypifiedbyadiscussionofthelimitationsofthetechnique.Withthedescriptionandarrangementgiveninthefollowingportionsofthistestmethod,theinstrumentwillrecorddirectlythenormalspectralemittanceofaspecimen.However,thefollowingconditionsmustbemetwithinacceptabletolerance:Theeffectivetemperaturesofthespecimenandblackbodymustbewithin1Kofeachother.Practicallimitationsarise,however,becausethetemperatureuniformitiesareoftennotbetterthanafewdegreesKelvin.Theopticalpathlengthinthetwobeamsmustbeequal,ortheinstrumentshouldoperateinanonabsorbingatmosphereoravacuum,inordertoeliminatetheeffectsofdifferentialatmosphericabsorptioninthetwobeams.Measurementsinairareinmanycasesimportant,andwillnotnecessarilygivethesameresultsasinavacuum,thustheequalityoftheopticalpathsfordualbeaminstrumentsbecomesverycritical.Note38212;Verycarefulopticalalignmentofthespectrophotometerisrequiredtominimizedifferencesinabsorptancealongthetwopathsoftheinstrument,andcarefuladjustmentofthechoppertimingtoreducex201C;cross-talkx201D;(theoverlapofthereferenceandsamplesignals)aswellasprecautionstoreducestrayradiationinthespectrometerarerequiredtokeepthezerolineflat.Withthebestadjustment,thex201C;100%linex201D;willbeflattowithin3%;bothofthesemeasurementsshouldbereproduciblewithintheselimits(see7.3,Note6).Front-surfacemirroropticsmustbeusedthroughout,exceptfortheprisminprismmonochromatorsandthegratingingratingmonochromators,anditshouldbeemphasizedthatequivalentopticalelementsmustbeusedinthetwobeamsinordertoreduceandbalanceattenuationofthebeamsbyabsorptionintheopticalelements.ItisrecommendedthatopticalsurfacesbefreeofSiO2andSiOcoatings;MgF2maybeusedtostabilizemirrorsurfacesforextendedperiodsoftime.Theopticalcharacteristicsofthesecoatingsarecritical,butcanberelaxedifallopticalpathsarefixedduringmeasurementsortheincidentanglesarenotchangedbetweenmodesofoperation(duringx201C;0%line,x201D;x201C;100%line,x201D;andsamplemeasurements).Itisrecommendedthatallopticalelementsbeadequatelyfilledwithenergy.Thesourceandfieldaperturesofthetwobeamsmustbeequalinordertoensurethatradiantfluxinthetwobeamscomparedbytheapparatuswillpertaintoequalareasofthesourcesandequalsolidanglesofemission.Insomecasesitmaybedesirabletodefinethesolidangleofthesourceandsamplewhencomparingalternativemeasurementtechniques.Theresponseofthedetector-amplifiersystemmustvarylinearlywiththeincidentradiantflux.1.1Thistestmethoddescribesahighlyaccuratetechniqueformeasuringthenormalspectralemittanceofelectricallyconductingmaterialsormaterialswithelectricallyconductingsubstrates,inthetemperaturerangefrom600to1400K,andatwavelengthsfrom1to35x03BC;m.1.2Thetestmethodrequiresexpensiveequipmentandratherelaborateprecautions,butproducesdatathatareaccuratetowithinafewpercent.Itissuitableforresearchlaboratorieswherethehighestprecisionandaccuracyaredesired,butisnotrecommendedforroutineproductionoracceptancetesting.However,becauseofitshighaccuracythistestmethodcanbeusedasarefereemethodtobeappliedtoproduction......
【中国标准分类号】:A43
【国际标准分类号】:71_040_50
【页数】:6P.;A4
【正文语种】:英语