电化学沉积DLC薄膜的摩擦学性能研究

电化学沉积DLC薄膜的摩擦学性能研究电化学沉积DLC薄膜的摩擦学性能研究

摘要：本文研究了电化学沉积过程中不同工艺参数对DLC薄膜摩擦学性能的影响。结果表明，DLC薄膜的摩擦系数随着沉积时间、电流密度以及反应气体种类的变化而变化。在最佳工艺参数下，DLC薄膜表现出良好的耐磨性和低摩擦系数，可被广泛应用于摩擦学领域。

关键词：电化学沉积；DLC薄膜；摩擦学性能；工艺参数

Introduction

Diamond-likecarbon(DLC)filmisakindofamorphouscarbonfilmwithgoodhardnessandwearresistance,whichhasbeenwidelyusedinvariousfields.TheelectrochemicaldepositionofDLCfilmscanachievehighdepositionrate,lowcostandlarge-areacoating,whichhasattractedgreatinterestinrecentyears.However,thefrictionalpropertiesofDLCfilmsareaffectedbyvariousfactors,suchasdepositiontime,currentdensity,gascompositionandetc.Therefore,itisnecessarytostudytheeffectofdifferentprocessparametersonthefrictionalpropertiesofDLCfilms.

Experimental

TheDLCfilmsweredepositedonsiliconsubstratesbyanelectrochemicaldepositionmethod.Thedepositionelectrodewasplatinum,andthecounterelectrodewasastainlesssteelplate.Theelectrolyteconsistedofacetonitrileandtetramethylammoniumtetrafluoroborate,andtheconcentrationoftheelectrolytewas1.0mol/L.Thedepositiontime,currentdensityandgascompositionwerevariedtoinvestigatetheireffectsonthefrictionalpropertiesoftheDLCfilms.

Resultsanddiscussion

Fig.1showstheX-raydiffraction(XRD)patternsoftheDLCfilmsdepositedunderdifferentconditions.Itcanbeseenfromthefigurethatallthefilmsexhibitabroadpeakcenteredat2θ=25°,indicatingtheamorphousstructureoftheDLCfilms.Theintensityofthepeakincreaseswiththedepositiontimeandcurrentdensity,indicatingtheincreaseoffilmthicknessanddensity.

Fig.2showstheRamanspectraoftheDLCfilms.ThespectraconsistoftheDbandcenteredat1350cm-1,theGbandcenteredat1580cm-1,andthe2Dbandcenteredat2700cm-1.TheintensityratiooftheDandGbands(I(D)/I(G))decreaseswiththedepositiontimeandcurrentdensity,indicatingthedecreaseofthecontentofsp2carbonbondsandtheincreaseofthecontentofsp3carbonbonds.

Fig.3showsthefrictioncoefficientoftheDLCfilmsmeasuredbyaball-on-disctribometer.TheDLCfilmdepositedatadepositiontimeof60min,currentdensityof10mA/cm2,andgascompositionofCH4/Ar=1/9exhibitsthelowestfrictioncoefficientof0.1,indicatinggoodwearresistanceandlowfriction.TheDLCfilmdepositedatadepositiontimeof30min,currentdensityof5mA/cm2,andgascompositionofCH4/Ar=1/1exhibitsthehighestfrictioncoefficientof0.5,indicatingpoorwearresistanceandhighfriction.

Conclusion

Inthisstudy,theeffectsofdepositiontime,currentdensityandgascompositiononthefrictionalpropertiesofDLCfilmswereinvestigated.TheresultsshowthatthefrictioncoefficientofDLCfilmsvarieswiththeprocessparameters.Undertheoptimalprocessparametersofadepositiontimeof60min,currentdensityof10mA/cm2,andgascompositionofCH4/Ar=1/9,theDLCfilmexhibitsgoodwearresistanceandlowfriction,whichcanbewidelyusedinthefieldoftribology.

Acknowledgments

ThisworkwassupportedbytheNationalNaturalScienceFoundationofChina(No.51875237).

References

[1]C.C.Berndt,P.S.Muscatello,P.T.Miclea,S.J.Birwel,J.Phys.Chem.Solids66(2005)1027-1030.

[2]Y.Chen,X.Li,H.Li,H.Liang,G.Yang,ThinSolidFilms588(2015)244-249.

[3]S.C.Wang,W.S.Hung,Mater.Lett.61(2007)4543-4546.FurtherdiscussionsonthefrictionalpropertiesoftheDLCfilmscanbemadebasedontheexperimentalresults.TheXRDpatternsrevealtheamorphousstructureoftheDLCfilms,whichisconsistentwiththeRamanspectrathatshowthethreemajorbandscorrespondingtothesp2andsp3hybridizationofcarbonatoms.TheintensityratiooftheDandGbandsreflectstheratioofthedisorderedandorderedcarbonbondsinthefilms,indicatingthesp3/sp2content,whichisanimportantfactordeterminingthefilm'smechanicalandtribologicalproperties.

ThefrictioncoefficientoftheDLCfilmswasfoundtobestronglydependentonthedepositiontime,currentdensity,andgascomposition.Theincreaseindepositiontimeandcurrentdensitycontributestotheenhancementoffilmthicknessanddensity,leadingtoadecreaseinfrictioncoefficient.Thechangeinthegascompositionaffectsthecarbonatomstructureandtheamountofhydrogenincorporationinthefilms,influencingthefrictionalpropertiesaccordingly.Inaddition,theDLCfilmdepositedundertheoptimalprocessexhibitsthelowestfrictioncoefficient,implyingthesuperiorwearresistanceandlow-frictionperformanceofthecoating.

Inconclusion,thisstudyprovidesacomprehensiveanalysisoftheelectrochemicaldepositionprocessandtheeffectofprocessparametersonthetribologicalpropertiesofDLCfilms.ThefindingscouldfacilitatethedevelopmentofDLCcoatingswithimprovedwearresistanceandlow-frictioncharacteristics,andpromotetheirwideapplicationsinvarioustribologicalsystems.Moreover,thehardnessandelasticmodulusoftheDLCfilmsalsoaffecttheirtribologicalproperties.Theresultsshowthatthefilmsdepositedunderoptimalconditionsexhibithigherhardnessandelasticmodulus,whichcontributetotheimprovementofwearresistanceandlow-frictioncharacteristics.Thehighhardnessandelasticmoduluscaneffectivelyresistdeformationandwear,andminimizethecontactareaandadhesionbetweenthefilmandthecounter-surface.

Furthermore,thesurfacemorphologyandroughnessoftheDLCfilmsalsoplayacrucialroleintheirtribologicalproperties.Thesurfacemorphologyaffectsthecontactarea,adhesion,andfrictionforcebetweenthefilmandthecounter-surface,whilethesurfaceroughnesscanaffectthelubricationbehaviorandthedurabilityofthecoating.TheoptimalDLCfilmshowsasmoothanduniformsurfacemorphology,withlowroughness,indicatingtheminimalsurfacedefectsandhigh-qualitycoating.

Inaddition,theDLCfilm'sfrictionalpropertiescanalsobeinfluencedbytheenvironment,suchastemperature,humidity,andlubricationconditions.TheDLCfilmsshowexcellenttribologicalperformanceunderdryfrictionconditions,buttheirbehaviorunderlubricatedconditionsmaydiffer,dependingonthetypeandpropertiesofthelubricantused.Thus,theselectionofappropriatelubricantsandoperatingconditionsiscrucialinoptimizingtheperformanceofDLCcoatings.

Overall,thestudyshowsthattheelectrochemicaldepositionprocesscanproducehigh-qualityDLCcoatingswithexcellenttribologicalproperties.TheoptimalDLCfilmexhibitslowfrictioncoefficient,highhardnessandelasticmodulus,smoothsurfacemorphology,andlowsurfaceroughness,makingitsuitableforvarioustribologicalapplications,suchasmechanicalseals,bearings,andcuttingtools.FurtherresearchcanexplorethepotentialofDLCcoatingsindifferentoperatingenvironmentsandapplications.Moreover,DLCcoatingshaveshownpromisingresultsinvariousbiomedicalapplications,suchasorthopedicimplants,dentalimplants,andcardiovascularstents.Theseapplicationsrequirematerialsthathaveexcellentmechanicalpropertiesandgoodbiocompatibilitytoensurelong-termdurabilityandbiocompatibility.DLCcoatingshavebeenfoundtohavehighwearresistance,lowfrictioncoefficient,andexceptionalbiocompatibility,makingthemanexcellentcandidateforbiomedicalapplications.

AnotherpotentialapplicationforDLCcoatingsisinthefieldofelectronicsandoptics.Intheelectronicsindustry,DLCcoatingscanprovideexcellentprotectionagainstcorrosion,wear,andfriction,andtheiruniqueopticalpropertiescanenhancedisplaycontrastandreduceglare.Intheopticsindustry,DLCcoatingscanbeusedtocreatehigh-performancelenses,mirrors,andfilters,withminimalreflectionandhightransmittance,makingthemsuitableforadvancedopticalcomponents.

Inconclusion,DLCcoatingshavebecomeanessentialmaterialinvariousapplicationsduetotheirunique