SiCpAl膜微觀形貌及耐蝕性研究liminaryStudyonMicrostructureandCorrosionResistanceofpAlCompositeMaterialMicroarcOxidationFilmAbstractthispaperSiCpAlcompositematerialswerepreparedandmicroarcoxidationwasusedtoformoxidefilmsontheirsurface.ThemicrostructureandcorrosionresistanceofthesampleswereinvestigatedbySEMXRD,EDS,potentiodynamicpolarizationcurveandelectrochemicalimpedancespectroscopy(EIS).TheresultsshowedthatthemicroarcoxidationfilmcouldeffectivelyimprovethecorrosionresistanceofSiCpAlcompositematerial,andthecorrosionresistanceimprovedwiththeincreaseofoxidationtime.ThemicrostructureoftheoxidefilmwasmainlycomposedofAl_2O_3andSiO_2,andsmallamountsofAlSi-OandAl-Si-C-Ocompoundswerealsoformed.ThestudyprovidesatheoreticalbasisforimprovingthecorrosionresistanceofSiC_pAlcompositematerials.CpAlcompositematerialmicroarcoxidationorrosionresistanceSiCpAlcompositematerialshavebeenwidelyusedinaerospaceautomotiveandotherindustriesduetotheirhighspecificstrength,highmodulusandexcellentwearresistance.However,thepoorcorrosionresistanceofSiCpAlcompositematerialshaslimitedtheirapplicationinharshenvironmentsInrecentyears,manystudieshavefocusedontheimprovementofthecorrosionresistanceofSiC_pAlcompositematerials[1-3].xidationMAOisasurfacemodificationtechnologythatuseshighvoltagepulsestoproduceadense,hard,wear-resistant,andcorrosionresistantceramiccoatingonmetaloralloysurfaces.TheformedoxidefilmhasaporousstructureandgoodbondingstrengthwiththesubstrateTheapplicationofMAOtechnologytoSiC_pAlcompositematerialscaneffectivelyimprovetheircorrosionresistanceandextendtheirservicelife[4,5].parationiCpAlcompositematerialswerepreparedbypowdermetallurgyAlpowderandSiCparticlesweremixedinaballmillfor8h,andthenpressedintoacylindricalmoldwithadiameterof20mmandaheightof20mmunderapressureof50MPa.Thegreencompactsweresinteredinavacuumfurnaceat650°Cfor2htoobtaintheSiC_pAlcompositematerials.TheMAOprocesswascarriedoutinaNa_2SiO_3-KOHelectrolytesolutionThecurrentdensitywas10A/dm^2,andthevoltagewasvariedfrom300to500V.Theoxidationtimewas10,20,and30min,respectively.zationThemicrostructureofthesampleswasobservedbyscanningelectronmicroscopy(SEM).Thechemicalcompositionoftheoxidefilmwasanalyzedbyenergydispersivespectroscopy(EDS).ThephasecompositionofthesampleswasexaminedbyX-raydiffraction(XRD).Theelectrochemicalperformanceofthesampleswasevaluatedbypotentiodynamicpolarizationcurveandelectrochemicalimpedancespectroscopy(EIS).ddiscussionctureTheSEMimagesofSiC_pAlcompositematerialsbeforeandafterMAOtreatmentareshowninFig.1.Itcanbeseenthatthesurfaceoftheuntreatedsamplewassmoothandflat,whilethesurfaceoftheMAOtreatedsamplehadaporousstructure.TheporeswereevenlydistributedonthesurfaceandthesizeincreasedwiththeincreaseofoxidationtimeTheoxidefilmwastightlyadheredtothesubstrateanddidnotpeeloff,indicatingthatthebondingstrengthbetweentheoxidefilmandthesubstratewasgood.agesofSiCpAlcompositematerialsbeforeandafterstheEDSspectraoftheuntreatedandMAOtreatedsamplesTheEDSspectrumoftheuntreatedsampleshowedmainlyAlandSielementswhiletheEDSspectrumoftheMAO-treatedsampleshowedanadditionalpeakofOelementindicatingtheformationofanoxidefilmonthesurfaceofthesample.pectraofSiCpAlcompositematerialsbeforeandaftermpositionsentstheXRDpatternsoftheMAOtreatedsamplesThepeaksat2θ=24.30°,36.10°,and61.20°intheXRDpatternoftheuntreatedsamplecorrespondedtothe(111),(200),and(220)crystalplanesofAl,respectively.Also,thepeakat2θ=35.60°correspondedtothecrystalplaneofSiC.Incontrast,theXRDpatternoftheMAO-treatedsampleshowedpeaksat2θ=27.50°,34.10°,and61.10°,whichmatchedwellwiththe(012),(104),and(110)crystalplanesofαAlO_3,respectively.ThepresenceofAl_2O_3indicatedthattheMAOfilmwasmainlycomposedofAl_2O_3.Inaddition,smallamountsofSiOandAl-Si-OcompoundswereformedonthesurfaceoftheMAOfilm.tternsofMAOtreatedSiCpAlcompositematerialsnresistanceThepotentiodynamicpolarizationcurvesofSiC_pAlcompositematerialsbeforeandafterMAOtreatmentareshowninFig.4.ThecorrosionpotentialEcorrcorrosioncurrentdensity(I_corr),andpolarizationresistanceRpofthesamplesaresummarizedinTable1.odynamicpolarizationcurvesofSiCpAlcompositereandafterMAOtreatmentAsshowninTable1,thecorrosionpotentialoftheuntreatedsamplewas0.325V,andthecorrosioncurrentdensitywas9.576×-8A/cm^2.AfterMAOtreatment,thecorrosionpotentialofthesamplesincreasedandthecorrosioncurrentdensitydecreased.Thecorrosionresistanceofthesampleswassignificantlyimproved,anditwasfoundthatthecorrosionresistanceofthesamplesincreasedwiththeincreaseoftheoxidationtime.Table1ElectrochemicalpropertiesofSiC_pAlcompositematerialsMAOtreatmentnntheNyquistplotsofSiCpAlcompositematerialsreandafterMAOtreatmentTheimpedanceZofthesamplesferentfrequencieswasanalyzedandfittedbyequivalentcircuithefittingresultsaresummarizedinTablestplotsofSiCpAlcompositematerialsbeforeandAOtreatmentTable2FittingresultsoftheequivalentcircuitmodelAsshowninTable2,theresistanceoftheoxidefilm(R_ct)increasedsignificantlyafterMAOtreatment,indicatingthattheoxidefilmhadgoodcorrosionresistance.Thequalityfactor(Q_f)andpower-lawindexn)ofthesamplesincreasedwiththeincreaseofoxidationtimeTheoxidefilmexhibitedcapacitivebehavior,whichfurtherillustratedthattheoxidefilmhadgoodcorrosionresistance.lusionMAOtechnologywasusedtoformoxidefilmsonthesurfaceofSiCpAlcompositematerials,andthemicrostructureandcorrosionresistanceofthesampleswereinve