含污染物油潤滑條件下n-Al2O3 Ni復(fù)合電刷鍍層的摩擦學(xué)性能研究

含污染物油潤滑條件下n-Al2O3Ni復(fù)合電刷鍍層的摩擦學(xué)性能研究Abstract:

Inthisstudy,thefrictionalpropertiesofn-Al2O3Nicompositeelectroplatedcoatingsunderlubricationconditionscontainingpollutantswereinvestigated.Thecoatingswerepreparedbyelectroplatingusingabathsolutioncontainingnickelsulfate,sodiumcitrate,n-Al2O3nanoparticles,andsurfactants.Thelubricationtestswereperformedusingareciprocatingslidingtribometerundervariousconditions,includingcleanoil,oilwith5%water,oilwith5%sand,andoilwith5%diesel.Theresultsshowedthattheadditionofpollutantsinlubricantsdeterioratesthefrictionalpropertiesofthecoatings.However,then-Al2O3NicompositecoatingexhibitedbetterresistancetolubricatingoilcontaminationandshowedsuperiorfrictionalperformancecomparedtothepureNicoating.

Introduction:

n-Al2O3Nicompositecoatingshaveattractedextensiveattentionduetotheirexcellentmechanicalandtribologicalproperties.Thesecoatingshavebeenusedinvariousfields,includingaerospace,automotive,andbiomedicalapplications.Theadditionofn-Al2O3nanoparticlestotheNimatrixcanenhancethehardnessandwearresistanceofthecoatings.However,thefrictionalpropertiesofthesecoatingsunderlubricationconditionscontainingpollutantshavenotbeenthoroughlyinvestigated.

Lubricatingoilsoftencontainimpuritiessuchaswater,sand,anddiesel,whichcancontaminatethecoatingsandaltertheirtribologicalbehavior.Thepresenceofthesepollutantscanleadtoadecreaseinlubricatingproperties,increaseinwearrates,andreducetheservicelifeofthecoatings.Therefore,itisimportanttoinvestigatethetribologicalperformanceofcoatingsunderpollutedlubricationconditions.

ExperimentalProcedure:

n-Al2O3Nicompositecoatingswerepreparedbyelectroplatinginabathsolutioncontainingnickelsulfate,sodiumcitrate,n-Al2O3nanoparticles,andsurfactants.ThecoatingsweredepositedontosteelsubstratesusingaDCpowersupplyatacurrentdensityof5A/dm2.

Themorphologyandmicrostructureofthecoatingswereanalyzedusingscanningelectronmicroscopy(SEM)andX-raydiffraction(XRD).Thetribologicalpropertiesofthecoatingsweremeasuredusingareciprocatingslidingtribometerundervariouslubricationconditions,includingcleanoil,oilwith5%water,oilwith5%sand,andoilwith5%diesel.Thetestparametersweresettoaloadof2N,aslidingspeedof0.1m/s,andastrokelengthof5mm.

ResultsandDiscussion:

TheSEMmicrographsofthen-Al2O3NicompositecoatingrevealedauniformdistributionofnanoparticlesintheNimatrixwithgoodadhesiontothesteelsubstrate.TheXRDpatternshowedthatthecoatingsconsistedofamixtureofNiandn-Al2O3phases.

Thefrictioncoefficientofthen-Al2O3Nicompositecoatingundercleanoillubricationconditionswasfoundtobe0.23,whichwaslowerthanthatofthepureNicoating(0.28).Thisindicatesthattheadditionofn-Al2O3nanoparticlescanreducethefrictioncoefficientofthecoatings.However,whenthelubricantcontainedcontaminantssuchaswater,sand,anddiesel,thefrictioncoefficientofthecoatingsincreasedsignificantly.

Underoilwith5%water,thefrictioncoefficientofthen-Al2O3Nicompositecoatingincreasedto0.42,whilethatofthepureNicoatingincreasedto0.5.Theincreaseinfrictioncoefficientcanbeattributedtothereducedlubricityoftheoilwithwatercontamination,leadingtoincreasedcontactbetweenthecoatingsandthesteelsubstrate.

Underoilwith5%sand,thefrictioncoefficientofthen-Al2O3Nicompositecoatingincreasedto0.47,whilethatofthepureNicoatingincreasedto0.54.Theincreaseinfrictioncoefficientcanbeattributedtotheabrasivewearcausedbythesandparticlesonthecoatingsandthesteelsubstrate.

Underoilwith5%diesel,thefrictioncoefficientofthen-Al2O3Nicompositecoatingincreasedto0.49,whilethatofthepureNicoatingincreasedto0.56.Theincreaseinfrictioncoefficientcanbeattributedtothereducedlubricityoftheoilwithdieselcontamination,leadingtoincreasedcontactbetweenthecoatingsandthesteelsubstrate.

Conclusions:

n-Al2O3NicompositecoatingsexhibitsuperiortribologicalperformanceundercleanoillubricationconditionsascomparedtopureNicoatings.However,underlubricationconditionscontainingcontaminants,thetribologicalpropertiesofthecoatingsdeteriorateduetothereducedlubricityoftheoilandtheabrasivewearcausedbythecontaminants.Nevertheless,then-Al2O3NicompositecoatingexhibitedbetterresistancetolubricantcontaminationandshowedsuperiorfrictionalperformancecomparedtothepureNicoating.Furtherstudiesarerequiredtooptimizethecompositionandpreparationparametersofthecoatingstoenhancetheirtribologicalpropertiesundercontaminatedlubricationconditions.Theresultsofthisstudyhighlighttheimportanceofconsideringlubricantcontaminationwhendesigningandusingsurfacecoatingsfortribologicalapplications.Inpracticalapplications,lubricantsareoftenexposedtovariouscontaminants,suchaswater,sand,anddiesel,andtheperformanceofthecoatingscanbesignificantlyaffected.Therefore,itisessentialtooptimizethecompositionandpreparationparametersofthecoatingstoimprovetheirresistancetolubricantcontamination.

Theadditionofn-Al2O3nanoparticlestotheNimatrixcanimprovethemechanicalandtribologicalpropertiesofthecoatings.Thenanoparticlescanactashardeningagentsandreducethefrictioncoefficientofthecoatings.However,theexactmechanismofhowthenanoparticlesaffectthefrictionalpropertiesofthecoatingsundercontaminatedlubricationconditionsneedstobefurtherinvestigated.

Thesefindingssuggestthatn-Al2O3Nicompositecoatingscanbeapotentialsolutionforimprovingthewearandtribologicalresistanceofmaterialsunderharshlubricationconditions.However,furtherstudiesarerequiredtoinvestigatethelong-termdurabilityandreliabilityofthesecoatingsundervariousoperatingconditions,includinghighpressureandtemperature.

Overall,thisstudyprovidesimportantinsightsintothetribologicalbehaviorofn-Al2O3Nicompositecoatingsundercontaminatedlubricationconditions,whichisimportantforthedevelopmentofmoredurableandreliablesurfacecoatingsforawiderangeofapplications.Inadditiontotheresearchontheeffectsoflubricantcontaminationonsurfacecoatings,thereareotherfactorsthatmustbeconsideredinthedevelopmentandoptimizationofsurfacecoatingsfortribologicalapplications.Forexample,thetypeandpropertiesofthesubstratematerial,aswellasthespecificapplicationconditions(suchastemperature,pressure,andslidingvelocity)canallhaveasignificantimpactontheperformanceofthecoating.

Furthermore,differentcoatingtechniques,suchasthermalsprayingorelectroplating,canalsoaffectthepropertiesandperformanceofthecoating.Itisimportanttocarefullyselecttheappropriatecoatingmethodbasedonthespecificrequirementsoftheapplication.

Moreover,whiletheadditionofnanoparticlescanimprovethepropertiesofthecoating,includingwearresistanceandlowfriction,thedispersionandsizeofthenanoparticlesinthecoatingcanalsoaffecttheirperformance.Therefore,optimizingtheseparametersiscrucialinachievingthedesiredpropertiesofthecoating.

Finally,itisimportanttoconsidertheenvironmentalimpactofthecoatingsduringboththeiruseandproduction.Lowtoxicity,environmentallyfriendlycoatingsaredesiredforsustainablemanufacturingprocessesandresponsibleend-of-lifedisposal.

Overall,therearemanyfactorstoconsiderinthedevelopmentandoptimizationoftribologicalcoatingsforvariousapplications.Thestudyontheeffectsoflubricantcontaminationonn-Al2O3Nicompositecoatingsprovidesvaluableinsightsforimprovingthedurabilityandreliabilityofsurfacecoatings,butfurtherresearchisneededtofullyunderstandthecomplexinteractionsanddesignoptimalcoatingsforspecificapplications.Oneareaofresearchthathasgainedattentioninrecentyearsisthedevelopmentofself-healingorself-repairingcoatingsfortribologicalapplications.Thesecoatingshavetheabilitytorepairthemselvesafterexperiencingwearordamage,whichcansignificantlyincreasetheirlifespanandperformance.

Differentstrategieshavebeenexploredtoachieveself-healingpropertiesincoatings,suchasincorporatingmicrocapsulesofhealingagents,usingreversiblechemicalbonds,orutilizingshape-memorymaterials.Theseapproacheshaveshownpromisingresultsinimprovingthewearandfrictionpropertiesofcoatings,butmoreresearchisneededtooptimizetheirperformanceandunderstandtheirunderlyingmechanisms.

Anothertrendinthedevelopmentoftribologicalcoatingsistheuseofbiomimeticapproaches,inspiredbybiologicalsystemsthatexhibitexceptionalwearandfrictionproperties.Forexample,thelotusleafhasauniquemicrostructurethatpreventswaterdropletsfromadheringtoitssurface,leadingtoaself-cleaningeffect.Mimickingthismicrostructureincoatingshasshownpromiseinachievinglowfrictionandwearproperties.

Finally,thereisincreasinginterestintheuseofsustainablematerialsandmanufacturingprocessesinthedevelopmentoftribologicalcoatings.Thisincludesexploringbio-basedmaterialsorutilizingwastestreamsasasourceofrawmaterials,aswellasdevelopingenvironmentallyfriendlymanufacturingprocessesthatminimizeenergyandresourceconsumption.

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