Thermal Conductivity of Some Solids.pdf

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1、VII.THERMALCONDUCTIVITYOFSOMESOLIDSCONTENTSA.PrefacetoThermalConductiviyIntegralsB.CoppersC.SilverandGoldD.BerylliumandMagnesiumE.Aluminum,Gallium,IndiumandThalliumF.TinandLeadG.Vanadium,NiobiumandTantalumH.Chromium,MolybdenumandTungstenI.Iron,Co-baltand

2、NickelJ.Rhodium,Palladium,IridiumandPlatinumK.CopperAlloysL.Copper-NickelandSilverAlloysM.AluminumAlloysN.NickelAlloys0.MiscellaneousAlloysP.GlassesandPlasticsQ.CarbonandStainlessSteelsR.70/30BrassS.FerrousAlloysAdditionalReferencetoEntireChapter:NBSCirc

3、ular556VII-INDEXPREFACEtotheTHERMALCONDUCTIVITYINTEGRALSofSOLIDSatLOWTEMPERATUmSThethermalconductivityintegralsformetallicsolidsarepresentedinthissectionasafunctionoftemperatureforthe0rangefrom4to300K.ThethermalconductivityintegralisdefinedfromtheFourier

4、equationforsteadyunidirectionalcon-ductionwhichis:dTQ=hA-dLwhere:Q=rateofheatconduction,negativeinthedirec-tionofincreasinglengthh.=thermalconductivityR=cross-sectionalareaoftheheatconductionpath,andnormaltothedirectionofheatflow--dT-temperaturegradienta

5、lonathepathatthesectiondLunderconsiderationT=temperatureL=lengthForaconstantcross-sectionareathismaybereducedto:L.;?T2"=JhdTT1whereTandT2arethetemperaturesatanytwopointsalongthe1pathoftheheatflow.Thethermalconductivityintegralstabulatedinthissectionareva

6、luesof:JTOwhereT2ndTaretemperaturesalongaheatflowpathcommuni-catinggetweenLheatreservoirsatT=4OKandTatlengthLfromT.Theheatflowalongaconductor0ofconstantLcross-section0areaA,throughlengthL,maythenbedeterminedfromthediffer-enceofthethermalconductivityinteg

7、rals,i.e.,(Continuedonfollowingpage)VII-A-LTTO0(Incalculatingthevaluesofthethermalconductivityintegralspresentedinthissection,alinearinterpolationwasassumedbetweenthetemperatureintervalstabulatedonthedatasheets.)Ofthemetalsincluded,fourbecomesuperconduct

8、ingabove40K.Thesemetalsandtheirtransitiontemperaturesare:*MetalsIndexTransitionTemperatureLead13.142-37.22OKNiobium13.1518.7-a.g°KTantalum13.1514.383Vanadium13.1514.89KThevaluesofthethermalconductivityforthesemetalsbelowth