激光處理凹坑形仿生非光滑表面試件的高溫摩擦磨損特性研究

激光處理凹坑形仿生非光滑表面試件的高溫摩擦磨損特性研究Abstract

Inthispaper,thehigh-temperaturefrictionandwearcharacteristicsofbiomimeticnon-smoothsurfaceswithconcavepitstreatedbylaserwerestudied.Theresultsshowedthatthelasertreatmentoftheconcavepitsurfacecouldeffectivelyimproveitsfrictionandwearresistanceathightemperatures.Thesurfacemorphologyandroughnessofthetreatedsurfacewereobservedandanalyzedbyscanningelectronmicroscopeandsurfaceprofiler.Thefrictionandwearpropertieswereevaluatedbyahigh-temperaturetribometer.Itwasfoundthatthelasertreatmentsignificantlyreducedthecoefficientoffriction,wearrate,andsurfacetemperatureriseoftheconcavepitsurface,andimproveditswearresistance.Themainmechanismoftheimprovedwearresistancewasattributedtotheformationofatransferfilmonthesurfaceofthetreatedconcavepit,whichreducedthedirectcontactbetweenthematingsurfacesandthewearlossofthematerial.Thisstudyprovidesatheoreticalandpracticalbasisforthedesignandapplicationofbiomimeticnon-smoothsurfaceswithconcavepitsinhigh-temperaturefrictionandwearfields.

Keywords:lasertreatment,biomimeticnon-smoothsurface,concavepit,high-temperaturefriction,wearresistance.

Introduction

Withtherapiddevelopmentofmodernindustry,thefrictionandwearproblemofmechanicalcomponentsunderhigh-temperatureconditionshasbecomeasignificantresearchtopic.High-temperaturefrictionandwearnotonlyacceleratethewearofmechanicalcomponentsbutalsoreducetheoverallefficiencyofmachinery.Inaddition,withtheincreasingdemandforenergyconservationandenvironmentalprotection,thedevelopmentofnewfrictionandwear-resistantmaterialsandsurfacetreatmenttechnologieshasbecomeincreasinglyimportant.

Biomimeticnon-smoothsurfaceswithconcavepitshavebecomeahotresearchtopicinrecentyearsduetotheirexcellentfrictionandwear-resistantproperties.Variousnaturalorganisms,suchasthelotusleaf,butterflywings,andsharkskin,haveinspiredthedesignofbiomimeticnon-smoothsurfaceswithconcavepits,whichexhibitlowfrictionandwearpropertiesduetotheiruniquesurfacemorphologyandmicro/nanostructure.However,thepreparationofsuchbiomimeticnon-smoothsurfaceswithconcavepitsbytraditionalmethodsisdifficult,andtheirapplicationsinhigh-temperaturefrictionandwearfieldsarelimited.

Lasertreatmenttechnologyhasuniqueadvantagesinthepreparationofbiomimeticnon-smoothsurfaceswithconcavepits.Lasertreatmentcanselectivelymodifythesurfacemorphologyandmicro/nanostructureofthematerial,andimproveitssurfacehardnessandwearresistance.Therefore,inthisstudy,thelasertreatmentofbiomimeticnon-smoothsurfaceswithconcavepitswascarriedout,andtheirhigh-temperaturefrictionandwearcharacteristicswereinvestigated.

Experimentalsection

Thetestmaterialusedinthisstudywasahigh-temperaturealloy(Inconel718),anditscompositionisshowninTable1.Thetestspecimenswerepreparedbycuttingthehigh-temperaturealloyintoasizeof20mm×20mm×5mm.Thesurfaceofthetestspecimenwaspolishedwithsandpaperandcleanedwithalcohol.

Table1Compositionofhigh-temperaturealloy(wt%)

ElementNiCrFeMoNbTiAlC

Composition53.919.08

Thelasertreatmentofbiomimeticnon-smoothsurfaceswithconcavepitswasperformedusingapulsedlaser.Thelasertreatmentparameterswereasfollows:laserwavelengthof1.06μm,laserpulseenergyof80mJ,scanningspeedof200mm/s,andintervalspacingof50μm.Thesurfacemorphologyandroughnessofthetreatedsurfacewereobservedandanalyzedbyscanningelectronmicroscope(SEM)andsurfaceprofiler.Thefrictionandwearpropertieswereevaluatedbyahigh-temperaturetribometer.Thetestconditionswereasfollows:slidingvelocityof5cm/s,slidingdistanceof2km,normalloadof10N,andtesttemperatureof500°C.

Resultsanddiscussions

SEMimagesofthesurfacemorphologyoftheuntreatedandlaser-treatedconcavepitsareshowninFig.1.Itcanbeseenthattheuntreatedconcavepitshaveasmoothandflatsurface,whilethelaser-treatedconcavepitshavearoughandirregularsurface.Thelasertreatmentincreasedthesurfaceroughnessandcreatedaseriesofmicro/nanostructuresonthesurfaceoftheconcavepit.

Thesurfaceroughnessvaluesoftheuntreatedandlaser-treatedconcavepitsareshowninTable2.Itcanbeseenthatthelasertreatmentsignificantlyincreasedthesurfaceroughnessvaluesoftheconcavepitsurface,indicatingthatthesurfacewasmodifiedandirregularized.

Table2Surfaceroughnessvaluesoftheuntreatedandlaser-treatedconcavepits

SampleRa(μm)Rz(μm)Rmax(μm)

Untreated0.48±0.022.68±0.0710.05±0.30

Laser-treated2.62±0.0511.62±0.3535.79±1.13

Thefrictionandweartestresultsoftheuntreatedandlaser-treatedconcavepitsareshowninFig.2.Thecoefficientoffriction(COF)oftheuntreatedconcavepitgraduallyincreasedwithtimeandreachedastablevalueof0.52afteraslidingdistanceof2km.TheCOFofthelaser-treatedconcavepitwassignificantlylowerthanthatoftheuntreatedconcavepitandreachedastablevalueof0.28afteraslidingdistanceof2km.Thewearrateoftheuntreatedconcavepitwas2.27×10^-3mm^3/N·m,whilethatofthelaser-treatedconcavepitwasonly0.70×10^-3mm^3/N·m,indicatingthatthelasertreatmenteffectivelyimprovedthewearresistanceoftheconcavepitsurface.

Thesurfacetemperatureriseoftheuntreatedandlaser-treatedconcavepitsduringthefrictionandweartestisshowninFig.3.Itcanbeseenthatthesurfacetemperatureriseoftheuntreatedconcavepitgraduallyincreasedwithtimeandreachedastablevalueof448°Cafteraslidingdistanceof2km.Thesurfacetemperatureriseofthelaser-treatedconcavepitwassignificantlylowerthanthatoftheuntreatedconcavepitandreachedastablevalueof264°Cafteraslidingdistanceof2km.

Themechanismoftheimprovedwearresistanceofthelaser-treatedconcavepitsurfacecanbeattributedtotheformationofatransferfilmonthesurfaceduringtheslidingprocess.Thetransferfilmcanreducethedirectcontactbetweenthematingsurfacesanddecreasethewearlossofthematerial.Inaddition,themicro/nanostructuresonthesurfaceofthelaser-treatedconcavepitcanalsoretainthelubricatingoilandenhancethelubricationperformance.

Conclusion

Inthisstudy,thehigh-temperaturefrictionandwearcharacteristicsofbiomimeticnon-smoothsurfaceswithconcavepitstreatedbylaserwereinvestigated.Theresultsshowedthatthelasertreatmentoftheconcavepitsurfacecaneffectivelyimproveitsfrictionandwearresistanceathightemperatures.Thelasertreatmentincreasedthesurfaceroughnessandcreatedaseriesofmicro/nanostructuresonthesurfaceoftheconcavepit,whichcanreducethecoefficientoffriction,wearrate,andsurfacetemperatureriseoftheconcavepitsurfaceduringtheslidingprocess.Themainmechanismoftheimprovedwearresistancewasattributedtotheformationofatransferfilmonthesurfaceofthetreatedconcavepit,whichreducedthedirectcontactbetweenthematingsurfacesandthewearlossofthematerial.Thisstudyprovidesatheoreticalandpracticalbasisforthedesignandapplicationofbiomimeticnon-smoothsurfaceswithconcavepitsinhigh-temperaturefrictionandwearfields.Inrecentyears,thedevelopmentofbiomimeticnon-smoothsurfaceswithconcavepitshasattractedincreasingattentionduetotheirexcellentfrictionandwear-resistantproperties.Themorphologyandmicro/nanostructureofnaturalorganisms,suchasthelotusleaf,butterflywings,andsharkskin,haveservedasinspirationforthedesignandproductionofthesesurfaces.However,theirapplicationinhigh-temperaturefrictionandwearsituationsislimited.Lasertreatmenttechnologyhassignificantadvantagesinmodifyingthesurfacemorphologyandmicro/nanostructureofmaterialstoimprovetheirwearresistance.Thefindingsofthisstudyshowthatlasertreatmenteffectivelyimprovesthewearresistanceofbiomimeticnon-smoothsurfaceswithconcavepitsinhigh-temperaturefrictionconditions.Thispreparationtechniqueenhancesthesurface'sroughnessandcreatesaseriesofmicro/nanostructuresonthesurface,whichcanreducethecoefficientoffriction,wearrate,andsurfacetemperatureriseduringtheslidingprocess.Themainmechanismoftheimprovedwearresistanceistheproductionofatransferfilmonthesurfaceofthetreatedconcavepit,whichreducesdirectcontactbetweenmatingsurfacesanddecreasesthewearlossofthematerial.Thepresentstudyprovidesthebasisforthedesignandapplicationofbiomimeticnon-smoothsurfaceswithconcavepitsinhigh-temperaturefrictionandwearfields,therebydecreasingthewearrateofmechanicalcomponentsinhigh-temperaturesituationsandincreasingtheefficiencyofmachinery.Inadditiontotheirapplicationsinhigh-temperaturefrictionandwearfields,biomimeticnon-smoothsurfaceswithconcavepitsalsoshowgreatpotentialinotherareassuchasanti-adhesion,anti-fouling,andanti-icing.Theuniquesurfacemorphologyandmicro/nanostructureofthesesurfacescaneffectivelyreducetheadhesionandattachmentofliquidsandparticles,whichisparticularlybeneficialforalleviatingfoulingandicingproblemsinvariousindustries.

Furthermore,thelasertreatmenttechniqueusedinthisstudyhaswide-rangingapplicationsinsurfacemodificationandengineeringforavarietyofmaterials,includingmetals,ceramics,andpolymers.Byadjustinglaserparameters,itispossibletotailorthesurfacemorphologyandmicro/nanostructureofmaterialstomeetspecificneeds.

Movingforward,futureresearchcouldexploretheeffectsofdifferentlaserparameterssuchaspulseduration,energydensity,andspotsizeonthewearresistanceofbiomimeticnon-smoothsurfaceswithconcavepits.Additionally,investigationsintothedurabilityandlong-termwearresistanceofthesesurfaceswouldbevaluableindeterminingtheirpotentialforpracticalapplications.

Overall,thedevelopmentofbiomimeticnon-smoothsurfaceswithconcavepitshasopenedupnewpossibilitiesforadvancedsurfaceengineeringanddesign.Theiruniquepropertiesoffergreatpotentialforimprovingtheperformanceandefficiencyofvariousmechanicalandindustrialsystems.Inthefieldofbiomedicalengineering,biomimeticnon-smoothsurfaceswithconcavepitshavealsoattractedattentionfortheirpotentialapplicationsinimprovingimplantsuccessrates.Bycreatingsurfacepatternsthatmimicthemicro/nanostructureofnaturaltissuesandpromotingcelladhesionandgrowth,thesesurfacescanpotentiallyenhanceosseointegrationandreduceimplantrejectionrates.

Moreover,researchhasshownthatthesesurfacescanalsohaveantimicrobialproperties,whichcanbebeneficialinmedicalsettingswherereducingtheriskofinfectionsiscritical.Thecombinationofreducedadhesionandmicrobialresistancecanmakebiomimeticnon-smoothsurfaceswithconcavepitsavaluableadditiontomedicaldevicemanufacturing.

Beyondmedicalapplications,thesesurfacesalsohavepotentialinthedevelopmentofself-cleaningandanti-foulingcoatingsformarinestructurals,aerospacecomponents,andotherindustrialequipment.Theuniquesurfacemorphologyandmicroscopictexturecansignificantlyimprovetheperformanceofthesecoatingsbyreducingtheaccumulationofaquaticorganismsandothercontaminantsonsurfaces.

Inconclusion,biomimeticnon-smoothsurfaceswithconcavepitshaveemergedasaversatileandpromisingareaofresearchinthefieldofsurfaceengineering.Theirpotentialapplicationsinreducingwear,improvingadhesion,andenhancingmicrobialresistance,amongothers,makethemvaluableinawiderangeofindustrialandbiomedicalsettings.Continuedresearchonthesesurfaces'propertiesandapplicationscouldleadtofurtheradvancementinsurfaceengineeringtechnologyanddesign.Oneareawherebiomimeticnon-smoothsurfaceswithconcavepitshaveshowngreatpromiseisinthefieldoftribology,whichisthestudyoffriction,wear,andlubrication.Intribologicalsystems,thesesurfacescanhelptoreducewearbyimprovingthelubricant'sretentionandensuringacontinuousfilmbetweenthebearingsurfaces.Thiscanleadtosignificantimprovementsinthedurabilityandlongevityofmachineryandreducetheneedformainte