Solution Layer and Critical Crevice Chemistry Studies .pdf

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1、SolutionLayerandCriticalCreviceChemistryStudies;R.G.KellyJuly13,2004SolutionLayerandCriticalCreviceChemistryStudiesR.G.KellyDepartmentofMaterialsScienceandEngineeringUniversityofVirginiaCharlottesville,VA22904rgkelly@virginia.eduSolutionLayerandCriticalCreviceChemistryStudies;R.G.KellyJuly13,2004Pro

2、ject1CorrosionCo-opThrustArea:CorrosioninThinLayersofMoistureandDepositsProjectTitle:EvolutionofSolutionLayerChemistryinthePresenceofDustPrincipalInvestigator:R.G.KellyInstitution:UniversityofVirginiaIntroductionMuchoftheexpectedcorrosionthatwilloccurintherepositorywilloccurunderatmosphericcorrosion

3、conditions,ratherthanfullimmersion.Thewatersthatseepthroughthetuffwilleitherdriporcondenseonthesurfaceofthewastepackagewiththeconditionsunderwhichthatoccursdependingstronglyonthefinaldesignandtheenvironmentalconditionsassumed.Thecorrosionmodesthatrepresentthemostthreattowastepackageintegrityarethose

4、thatarelocalized(pitting,crevicecorrosion,stress-corrosioncracking).Therehasbeenlimitedfundamentalstudyoflocalizedcorrosioninthinelectrolytes.Mostatmosphericcorrosionresearchhasfocusedonthemoreuniformcorrosionexhibitedbynickelandcopperwhenexposedtoatmospheresofdifferingrelativehumidity(RH),temperatu

5、re,andpollutantgastypeandconcentration[1-5].InordertovalidatemodelsofWPperformance,theplausibleextremesoftheWPenvironmentandsubsequentcorrosionneedtobeestablished.Toaccomplishthatrequiresacombinationofexperimentalandcomputationalworkthatfocusesonthecontrollingvariablesandestablishesascientificbasisf

6、orthepredictionofthestabilizationoflocalizedattackontheWP.Thisstabilizationinvolvestheconnectionbetweenastable,robustcathodicareaandthelocalizedcorrosionsite.Therobustnessofthecathodicareadependsinlargepartonthechemistry,electrochemistry,andtransportpropertiesinthethinelectrolytethatforms,whichwilli

7、ncludedustontheWPsurface.Understandingtheatmosphericelectrochemistryrequiresadeterminationoftheextenttowhichcathodicandanodicsitesunderthinfilmsandcoveredbydepositscommunicatewithoneanother.Thedegreet