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1、ThermalStabilityofSyntheticOilsinAviationApplicationsB.KochGermanAerospaceResearchCentre,StuttgartThethermaldecompositionofselectedsyntheticbasefluidshasbeeninvestigated.Theeffectsoftemperatureandtimeontherateandextentofthermaldegradationwerestudiedinamodifiedsteelbom
2、btestdevice.Theeffectsofchainlengthandbranchingareimportantfactorsinthethermalstabilityofhydrocarbonsandsimilarfluids.Inordertoovercomethe350°Climitofthermalstability,otherclassesofchemicalhavetobeused.Keywords:thermalstability,syntheticoils,aviation,testmethod,degrad
3、ationFinalmanuscriptapproved23November1989INTRODUCTIONOilsinaviationapplicationshavetomeetmanyrequirements.Inaircrafthydraulicsystems,thermalstabilityisofgrowinginterest.Aerospacesystemsforthefuturewithreducedoilquantitiesandhigherenginetemperatureswillgeneratethermal
4、stresswhichcannotbeovercomewiththecurrentstate-of-the-artfluids.Therefore,thermo-stabilityaspectsareofgrowinginterest.Consequently,newfluidshavetobedeveloped.Mostofthecandidatefluidsarecurrentlyveryexpensiveandonlyavailableinsmallquantities.Forthesereasons,testmethods
5、forsmallamountsareurgentlyrequired.Inthefollowingpaper,theinfluencingfactorsofchainlengthandchainbranchingofparaffinichydrocarbonsinthermalstabilityareinvestigatedtoestimatethehigh-temperaturelimit.Thestudyisextendedtoasilahydrocarbon(SiHC),whichisreportedtohavesuperi
6、orthermalstabilityandgoodviscosityproperties.1-6Toovercomethehigh-temperaturelimitationsofthefluidsmentioned,theclassofmaterialhastobechanged.Usefulexperimentshavebeenmadewiththeclassknownasperfluoropolyakylethers(F'FPAES),~-~andso,forcomparisonpurposes,oneexampleofth
7、isclasshasalsobeeninvestigated.ThePFPAEisalsousedtodemonstratetheefficiencyofthemodifiedtestdevicetomeasuresmalldegradationratesathightemperatures.FLUIDSINVESTIGATEDInthisstudy,hexadecane,hexamethyltetracosane(squalane),polyalphaolefins(hydrogenateddeceneoligomers,PAO
8、),aSiHC,andPFPAEwereinvestigatedJSL(6)2750265-6582$5.00+$2.00276KochJSL6-4comparatively.Structureformalaeandphysicalproperti
