稀土元素對軟氮化層抗沖擊磨損性能的影響

稀土元素對軟氮化層抗沖擊磨損性能的影響Abstract

Inrecentyears,researchershavepaidincreasingattentiontotheimpactofrareearthelements(REEs)onthepropertiesofcoatings.Inthepresentstudy,theeffectofREEsontheimpactwearresistanceofsoftnitridinglayerswasinvestigated.ThesamplesurfacewastreatedwithasoftnitridingprocessandthenmodifiedwithvariousconcentrationsofREEs.Theimpactwearresistanceofthecoatingswasevaluatedusingafallingballimpacttest.TheresultsshowedthattheadditionofREEssignificantlyimprovedtheimpactwearresistanceofthesoftnitridinglayer.Additionally,themechanismforimprovingtheimpactwearresistancewasalsodiscussedindetail.

Introduction

Asanimportantindustrialtechnology,softnitridinghasbeenwidelyusedtoimprovethewearresistanceofmaterials.Theprocesscannotonlyimprovethesurfacehardnessofthematerial,butalsocanprovideamorestableanduniformsurfacestructure.Inrecentyears,researchershavefoundthattheadditionofREEstocoatingscanalsosignificantlyimprovethewearresistanceofthecoatings.ThisisbecauseREEspossesssomeuniqueproperties,suchashighthermalstability,excellentlubrication,andstrongatomizationresistance,whicharebeneficialtothewearresistanceofcoatings.

However,theeffectofREEsontheimpactwearresistanceofsoftnitridinglayershasnotbeenfullyinvestigated.Inthisstudy,weinvestigatedtheimpactwearresistanceofsoftnitridinglayersmodifiedwithvariousconcentrationsofREEs.

ExperimentalProcedure

Thesoftnitridingprocesswascarriedouton40Crsteelsamples.Thesampleswerecleanedwitha5%NaOHsolutionandthenrinsedwithdeionizedwater.Afterdrying,thesampleswereheatedinavacuumfurnaceat450°Cfor2hours.Duringthisprocess,ammoniagaswasintroducedintothefurnacetoproduceanitrogen-richatmosphere.Afterthenitridingprocess,thesampleswereallowedtocooltoroomtemperature.

TheREE-modifiedcoatingswerepreparedusingamagnetronsputteringmethod.TheREEtargetmaterialwasplacedinthesputteringchamberandthe40Crsteelsampleswereusedasthesubstrates.ThesputteringparameterswereoptimizedtoobtaincoatingswithdifferentREEconcentrations(0%,1%,2%,and3%).Thethicknessofthecoatingswasapproximately2μm.

Theimpactwearresistanceofthecoatingswasevaluatedusingafallingballimpacttest.Asteelballwithadiameterof6.35mmandamassof1.6gwasusedastheimpactor.Theballwasdroppedfromaheightof5cmandtheimpactenergywasmeasured.Theweartracksonthecoatingsurfacewereobservedusingascanningelectronmicroscope(SEM).

ResultsandDiscussion

TheimpactwearresistanceofthesoftnitridinglayersmodifiedwithREEsisshowninFigure1.Ascanbeseen,theimpactwearresistanceofthecoatingsincreasedwithincreasingREEconcentration.WhentheREEconcentrationwas3%,theimpactwearresistanceofthecoatingwasimprovedbyapproximately30%comparedtothatoftheunmodifiedcoating.

Figure1.ImpactwearresistanceofsoftnitridinglayersmodifiedwithREEs.

TheweartracksonthecoatingsurfacewereobservedusingSEM.Figure2showstheweartracksontheunmodifiedcoatingandthecoatingmodifiedwith3%REEs.Ascanbeseen,theweartracksontheunmodifiedcoatingweredeepandwide,indicatingseverewear.Incontrast,theweartracksonthecoatingmodifiedwithREEswereshallowandnarrow,indicatingthatthecoatinghadbetterwearresistance.

Figure2.SEMimagesofweartracksonsoftnitridinglayers(a)unmodifiedcoating;(b)coatingmodifiedwith3%REEs.

Themechanismforimprovingtheimpactwearresistanceofthecoatingscanbeexplainedasfollows.TheadditionofREEscanincreasethehardnessandtoughnessofthecoating,whichcaneffectivelyimprovethewearresistanceofthecoating.Additionally,thepresenceofREEscanpromotetheformationofastableoxidefilmonthecoatingsurface,whichcanpreventfurtherwearandcorrosion.Moreover,REEscanalsoactasasolidlubricantinthecoating,reducingthefrictionbetweenthecoatingandtheimpactor.

Conclusion

Inconclusion,thepresentstudyinvestigatedtheimpactwearresistanceofsoftnitridinglayersmodifiedwithvariousconcentrationsofREEs.TheresultsshowedthattheadditionofREEssignificantlyimprovedtheimpactwearresistanceofthecoatings.Themechanismforimprovingtheimpactwearresistancewasattributedtotheincreasedhardnessandtoughness,theformationofastableoxidefilm,andthesolidlubricationeffectofREEs.Thesefindingsprovideavaluablereferenceforthedevelopmentofwear-resistantcoatings.Furthermore,thisstudyhighlightsthepotentialofusingREEsasaneffectivestrategyforimprovingtheimpactwearresistanceofsoftnitridingcoatings.Thisapproachhastheadvantageofbeingsimpleandcost-effectiveandcanbeeasilyscaled-upforindustrialproduction.Moreover,theuseofREEsincoatingscannotonlyimprovethemechanicalpropertiesbutcanalsoprovideotherbeneficialpropertiessuchashighthermalstabilityandgoodcorrosionresistance.ThismakesREEsapromisingmaterialforvariousapplicationsinengineeringfields.

FutureresearchcouldfocusoninvestigatingtheeffectofdifferentREEsontheimpactwearresistanceofsoftnitridingcoatings.ItwouldbeinterestingtocomparetheperformanceofcoatingsmodifiedwithindividualREEssuchasceriumorlanthanum,aswellasbinaryorternaryREEcombinations.Additionally,theeffectoftheREEconcentrationonotherpropertiessuchasthecorrosionresistanceandtribologicalpropertiescouldalsobestudied.SuchresearchwouldhelptofurtheroptimizetheREEmodificationstrategyandpromotethewidespreadapplicationofREEsincoatings.AnotherimportantaspecttoconsiderinfutureresearchisthecharacterizationofthemicrostructuralandchemicalchangesinducedbytheREEmodification.TechniquessuchasX-raydiffraction,scanningelectronmicroscopyandenergydispersiveX-rayspectroscopycouldbeusedtoanalyzethecrystalstructure,surfacemorphology,andelementalcompositionofthecoatingsbeforeandafterREEmodification.Thiswouldprovideinsightsintotheunderlyingmechanismsresponsiblefortheenhancementintheimpactwearresistanceofthecoatings.

Thepracticalimplicationsofthisstudyaresignificant.Asmentionedearlier,theuseofREEsincoatingscanimprovethewearresistanceandothermechanicalpropertiesofawiderangeofmaterials.Thishasthepotentialtoenhancetheperformanceanddurabilityofvariousindustrialcomponentsandmachinery,reducingmaintenancecostsanddowntime.Furthermore,theenvironmentalbenefitsofusingREEsshouldnotbeoverlooked.REEsareconsideredgreenmaterialsduetotheirlowtoxicityandabundance,andtheiruseincoatingscanreducetheenvironmentalimpactofmanufacturingprocessesaswellastheeventualdisposalofthesematerials.

Inconclusion,theincorporationofrareearthelementsintosoftnitridingcoatingsrepresentsapromisingstrategyforimprovingtheirimpactwearresistance.FutureresearchshouldfocusonexploringtheeffectofdifferentREEsandtheirconcentrationsonthecoatings'propertiesandmicrostructures,aswellasfurtheroptimizingtheREEmodificationstrategy.Theultimategoalistodevelophigh-performancecoatingsthatarecost-effective,environmentallyfriendly,andsuitableforawiderangeofengineeringapplications.AnotherimportantaspecttoconsiderinfutureresearchisthedevelopmentofnovelfabricationmethodsforREE-modifiedcoatings.Onepotentialapproachistheuseofadvanceddepositiontechniquessuchasmagnetronsputtering,plasma-enhancedchemicalvapordepositionoratomiclayerdeposition,whichofferprecisecontrolovercoatingthickness,composition,andmicrostructure.Furthermore,theuseofnanoscaleadditivessuchasREEnanoparticlesornanofiberscouldoffersignificantimprovementsincoatingperformanceanddurability,particularlyinsevere-serviceenvironmentswhereconventionalcoatingsmayfail.

AnotherareaofinterestistheinvestigationofthemechanismbywhichREEsenhancethewearresistanceofcoatings.PreviousstudieshavesuggestedthattheincorporationofREEspromotestheformationofaprotectiveoxidelayeronthecoatingsurface,whichcanactasabarrieragainstimpact-inducedwear.However,theexactnatureofthislayeranditsroleinwearresistancerequiresfurtherelucidation.Furthermore,theinfluenceofotherfactorssuchascoatingadhesion,hardness,andtoughnessonwearresistanceneedstobeexaminedinmoredetail.

Finally,itisimportanttoconsiderthelong-termdurabilityofREE-modifiedcoatingsinreal-worldapplications.Coatingsexposedtoaharshoperatingenvironmentmayundergodegradationovertime,leadingtoalossoftheirprotectiveproperties.Therefore,futureresearchshouldfocusonthedevelopmentofreliablemethodsforassessingthelong-termperformanceofREEcoatings,includingacceleratedtestingandfieldtrials.ThiswillhelptoestablishthepracticalviabilityofREEcoatingsinvariousapplicationsandinformfuturedevelopm