Wear Properties of A356/10SiC/1Gr Hybrid Composites in Lubricated Sliding Conditions

7/28/2019 Wear Properties of A356/10SiC/1Gr Hybrid Composites in Lubricated Sliding Conditions

1/7

148

Vol.35,No.2(2013)148154

TribologyinIndustry

www.tribology.fink.rs

WearPropertiesofA356/10SiC/1GrHybridCompositesinLubricatedSlidingConditions

M.Babia,B.Stojanovia,S.Mitrovia,I.Bobib,N.Miloradovia,M.Pantia,D.Dunia

aFacultyofEngineering,UniversityofKragujevac,Kragujevac,Serbia,bInstitutionInstituteofNuclearSciencesVinca,UniversityofBelgrade,Belgrade,Serbia.

Keywords:

Hybridcomposites

Aluminium

SiC

GraphiteWearLubrication

MML

ABSTRACTThis paper presents basic tribological properties of A356/10SiC/1Gr hybridcomposites in conditions with lubrication. Hybrid composite specimen isobtainedbycompocastingprocedure. A356aluminiumalloy isusedasabase

matrixalloy,reinforcedwith10wt%ofSiCand1wt%ofgraphite.Tribological

testsaredoneonadvancedandcomputersupportedtribometerwithblockondisc contact pair. By the experimental plan, test is conducted under threedifferentvaluesofslidingspeed,threedifferentvaluesofnormalload,different

slidingdistances,andalsodifferentlubricants.SEMandEDSareusedforwearanalysis.TheanalysishasshownthepresenceofMML,whichmeansthatthere

wastransferofmaterialfromsteeldisctocompositeblock.

2013PublishedbyFacultyofEngineering

Correspondingauthor:

BlaaStojanoviFacultyofEngineering,

UniversityofKragujevac,

Kragujevac,SerbiaEmail:[email protected]

1. INTRODUCTIONAluminium is the most attractive material in

automotive, airplane, space and precise devices

industry. Improvement of mechanical and

tribological properties of aluminium can beachieved through aluminium reinforcementwith

the proper material and through creatingcomposite material. The most effective

improvement of these properties is achieved

through creating hybrid compositeswith two or

more types of reinforcements. By adding theceramic reinforcement, mechanical properties of

thematrixarechanged,butinthatcaseproblemof

machinability occurs. To improve machinability,thegraphiteisaddedtocompositematerialsthat

are already reinforced with ceramic material.

Presence of graphite reduces mechanicalproperties (hardness decreases), but tribological

propertiesareimproved[15].

Basavarajappa et al [68] have studied thetribologicalbehaviourofhybridcompositeswith

aluminum base Al2219 reinforced by SiC andgraphite. They studied the tribological

propertiesofhybridcompositeswith5,10and

15%SiCand3%Gr obtainedwith processof

liquid metallurgy. The tribological tests showthatweardecreaseswithincreasingSiCcontent

inthehybridcomposite.Withincreasingsliding

speedandnormalload,wearrateofcompositesis growing. Mahdavi and Akhlaghi [9,10] have

R

ESEARCH


2/7

M.Babietal.,TribologyinIndustryVol.35,No.2(2013)148154

149

studiedthetribologicalpropertiesofAl/SiC/

Gr hybrid composites obtained by In situ

PowderMetallurgyprocess.AluminumalloyAl6061isusedasabasereinforcedwithgraphite9

%and040%SiC. Thetribological tests are

doneontribometerwithpinondisccontact,andthe composite with 20 % SiC has the best

properties. Further increase of SiC leads to

increasedwearofhybridcomposites.

Sureshaand Sridhara[1114] have studied the

effect of SiC content and graphite on the

tribological behaviour of hybrid Al/SiC/Gr

composites with aluminum base LM25 (AlSi7Mg0.5)obtainedbystircastingprocess.

AmesandAlpashave[15]studiedthetribological

testing of hybrid composites with a base ofaluminum alloy A356 reinforced with 20 % SiC

and310%Gr.Thetribologicaltestsaredoneontribometerwith block on ring contact.Thewear

rate of hybrid composites is significantly lower

than the wear rateof the basematerial without

reinforcements,especiallyatlownormalloads.

Vencl et al [16,17] have studied the tribological

behaviour of hybrid composites with the A356

matrixreinforcedwithSiC,Al2O3andgraphite.Thetribological testsaredoneontribometerwithpin

ondisccontactandshowthatthewearandfriction

coefficientdecreaseswithadditionofgraphite.

This paper presents tribological behaviour of

hybridcompositeswithaluminumbaseofA356alloy reinforcedwith SiC and Grobtainedwith

compocastingprocedure.Thetestsaredoneon

computeraidedblockondisctribometerunder

lubricated sliding conditions by varying thecontactpairs(slidingspeedandnormalload).

2. EXPERIMENT

2.1TheprocedureforobtainingcompositesHybridA356/SiC/Grcompositesareobtainedbythemodified compocasting procedure (infiltration of

particlesinthesemisolidifiedmeltA356alloy).subeutecticAlSialloysEnAlSiMg0,3(A356alloy)isused

as a basis. Using compocasting procedure, particle

reinforcements are easily infiltrated / trapped.This

solvestheproblemofwettabilityontheborderbaseandreinforcements.Thecostofcompositeproducing

withthatprocessismuchlower.

a)

b)

Fig.1.

Thestructure of:a)basematerialA356, andb)hybridcompositeA356/10SiC/1Gr.

Figure 1 shows the structure of the basematerial A356 and the hybrid composite with

10wt%SiC and 1wt%Gr. When mixing

composites, particles of graphite have become

fragmentedwithregardtooriginalsizeof35m.The picture shows the distribution of SiC

particulatereinforcements,thesizeof39um.

2.2Planofexperimentanddescriptionofequipment

Tribological tests are done on advanced and

computer supported tribometer with blockon

disccontactpair inaccordancewithASTMG77

standard.ContactpairconsistsofrotatingdiscofdiameterDd=35mmandbroadnessbd=6.35mm,

andastationaryblockofsize6.35x15.75x10.16

mm3. The discs are made of steel 90MnCrV8

hardnessof6264HRCwithgrindedsurfaces.

The tests were performed in lubricated sliding

conditionsonthesampleswiththebeststructural,

mechanicalandanticorrosiveproperties.


3/7


150

Fig.2.Tribometer.

Thevaluesofslidingspeed(0.25m/s,0.5m/s

and1m/s)and thenormal loads(40N,80N

and120 N) are in accordancewith theplan of

experiment.Thetestsareperformedforslidingdistanceof2400m.

Fig.3.Lubricationofthecontactpair.Alltestsusedthesamehydrauliclubricantwith

improved antiwear properties, viscosity VG46

(ISO3848).Lubricantishousedinasmalltank,

andlubricationisdonesothatthebottomofthediscisimmersedtouptodepthof3mmintothe

small tank with lubricant, whose volume is 30ml. During rotation of the disc, oil is

continuously introduced into the zone of thecontact and makes boundary lubrication of

contactpair(Fig.3).

Allexperimentswererepeated5times,andthe

mean values of obtained values are taken as

authoritative.

3.RESULTSOFTRIBOLOGICALTESTS

Resultsoftribologicaltestsofhybridcomposite

A356/10SiC/1Gr and basic material A356 areshowninthefollowingdiagrams.

V=0.25 m/s, lubrication

0 500 1000 1500 2000 2500

Sliding distance, m

0

1

2

3

4

5

6

7

8

9

Wear,mm

3x10-2

A356, F1=40N

A356, F2=80N

A356, F3=120N

A356/10SiC/1Gr, F1=40N

A356/10SiC/1Gr, F2=80N

A35610SiC/1Gr, F3=120N

V=0.5 m/s, lubrication

0 500 1000 1500 2000 2500

Sliding distance, m

0

1

2

3

4

5

6

7

8

Wear,mm

3x10-2

A356, F1=40N

A356, F2=80N

A356, F3=120N

A356/10SiC/1Gr, F1=40N

A356/10SiC/1Gr, F2=80N

A356/10SiC/1Gr, F3=120N

V=1 m/s, lubrication

0 500 1000 1500 2000 2500

Sliding distance, m

0

1

2

3

4

5

6

7

8

Wear,mm

3x10-2

A356, F1=40N

A356, F2=80N

A356, F3=120N

A356/10SiC/1Gr, F1=40N

A356/10SiC/1Gr, F2=80N

A356/10SiC/1Gr, F3=120N

Fig.4.Wearvolumeforallthreevaluesofslidingspeed.Diagramsofwearvolumeareformedonthebasis

ofwearscarwhichisobtainedbymeasuringafter

150m,300m,1200m,2400m,andtheyaregivenforallthreevaluesofslidingspeed(Fig.4).

It is obvious that the wear rate of the hybrid

composites A356/10SiC/1Gr is several timesless than the wear rate of the base material

A356.Withincreaseofslidingspeed,wearrate

of the hybrid composite A356/10SiC/1Gr andthe base material are decreases. Wear rate

dependencehasalmostlineardependenceforallvaluesofthenormalloads(Fig.5).


4/7


151

s=2400m,lubrication

0.00 0.25 0.50 0.75 1.00 1.25

Sliding speed, m/s

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

Wearrate,mm

3x10-5/m

A356, F1=40 N

A356, F2=80 N

A356, F3=120 N

A356/10SiC/1Gr, F1=40 N

A356/10SiC/1Gr, F2=80 N

A356/10SiC/1Gr, F3=120 N

Fig.5.Wearratedependenceonslidingspeed.

With increase of normal load, wear rate

increases. This increase is particularlypronouncedatthebasematerialA356(Fig.6).

s=2400m,lubrication

0 40 80 120 160

Load, N

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

Wea

rrate,mm

3x10-5/m

A356, V1=0.25 m/s

A356, V2=0.5 m/s

A356, V3=1.0 m/s

A356/10SiC/1Gr, V1=0.25 m/s

A356/10SiC/1Gr, V2=0.5 m/s

A356/10SiC/1Gr, V3=1.0 m/s

Fig.6.Wearratedependenceonnormalload.

Wear rate dependence on normal load and

sliding speed for sliding distanceof2400m, isshowninFig.7.

Fig. 7. Wear rate dependence on normal load andslidingspeed.

After the tribological tests, SEM analysis is

performed forwearscarofbasematerialA356

and hybrid A356/10SiC/1Gr composite, whosemicrophotosareshowninFig.8.

a)

b)

Fig. 8. SEM microphotos of wear scar: a) basematerialA356,b)hybridcompositeA356/10SiC/1Gr.4.ANALYSESOFOBTAINEDRESULTSTheanalysesoftheobtainedtribologicalresults

showthatthewearrateorwearvolumeismuchlowerinthehybridcompositesA356/10SiC/1Gr

comparedtothebasematerial.DecreaseofwearrateoccursduetotheeffectsofSiCfromhybrid

compositeincontactwithasteeldisc.

WearratedependenceonnormalloadandslidingspeedareshowninFigs.9and10asthe3Dplots.

Wearrateisapproximatedbyexponentialfunction

withahighcorrelationcoefficient.

Both tested materials show that at least wear

occursatthemaximumslidingspeedof1m/sandtheminimumnormalloadof40N.


5/7


152

Fig.9.Wearratedependenceonthebasematerial.

Fig. 10. Wear rate dependence on the hybridcomposites356/10SiC/1Gr.

Fig.11.The accumulation of iron in the compositeA356/10SiC/1Gr,120N,0.25m/s.

SEMmicroscopyshowsthatduetothecontactof

theSiCcompositesandSiphasesfromthebasic

A356, wear of steel disc occurs. Fe particlesenter the surface layer of the composites and

leadtothecreationofmechanicallymixedlayer

(MML). The formation of MML layer is

characteristic of aluminum alloys reinforcedwith SiC [1823]. Iron accumulates around the

SiCparticlestakingapositionofsmallparticleof

graphite. At some parts white lines appearenrichedwithironoxides,whichareconsistent

withtheslidingdirection(Fig.11).

Figure12showstheSEMphotographofpartofthehybrid composite A356/10SiC/1Gr.Wear scar is

obtainedbyslidingspeedof0.25m/sandnormal

loadof120Ninconditionsoflubrication.Athigher

loads, thedominantwearmechanismisabrasivewear. SiC particles (darker) and iron particles

(bright colours) are clearly visible on the scar.

Confirmationoftheseassumptionsisobtainedby

EDSanalysis,asshowninthetwospectrums.ThefirstspectrumshowsthepresenceofSiCparticles,

andtheparticlesofironanditsoxidescanbeseenonsecondspectrum.

Fig.12. EDS analysisA356/10SiC/1Gr, 120 N,0.25m/s,SEM.


6/7


153

5. CONCLUSION

WeartestsofhybridcompositesA356/10SiC/1Grshow their superior performance in relation to

the base material A356. Applied compocasting

modified procedure, in addition to low prices,confirmsthegooddistributionofreinforcements

inthecomposite.

Wear rate on A356/10SiC/1Gr hybridcomposites is38 timeslesser than thewear

rate onthe basematerial A356. It is especially

bigdifferenceofwearrateatthelowestsliding

speedof0.25m/sandmaximumnormalloadof120 N. Wear rate decreases with decrease of

normalloadandincreaseofslidingspeed.

SEM microscopy and EDS analysis confirm agood distribution of SiC reinforcements in the

hybrid composite. Also, advent mechanicallymixedlayer(MML)isobvious,respectively,the

appearanceofironanditsoxidesinthehybrid

composite.ACKNOWLEDGMENTSThispaperpresentstheresearchresultsobtained

within the frameworkof theproject TR35021,

financially supported by the Ministry of

EducationandScienceoftheRepublicofSerbia.REFERENCES[1] A.Vencl:TribologyoftheAlSialloybasedMMCs

and their application in automotive industry,u:

Magagnin L.(ed.),Engineered Metal Matrix

Composites: Forming Methods, Material

Properties and Industrial Applications, Nova

SciencePublishers,Inc.,NewYork(SAD),pp.127

166,2012.[2] B. Stojanovic,M. Babic, S.Mitrovic,A.Vencl,N.

Miloradovic, M. Pantic: Tribologicalcharacteristics of aluminium hybrid compositesreinforced with silicon carbide and graphite. Areview, Journal of the Balkan Tribological

Association,Vol.19,No.1,pp.8396,2013.

[3] N. Miloradovic, B. Stojanovic: Tribologicalbehaviour ofZA27/10SiC/1Gr hybrid composite,

Journal of the Balkan Tribological Association,

Vol.19,No.1,pp.97105,2013.

[4]S. Mitrovic, M. Babic, B. Stojanovic, N.Miloradovic, M. Pantic, D. Dzunic: Tribological

PotentialofHybridCompositesBasedonZincand

Aluminium Alloys Reinforced with SiC and

GraphiteParticles,Tribologyinindustry,Vol.34,

No.4,pp.177185,2012.

[5] P.Ravindran,K.Manisekar,R.Narayanasamy,P.Narayanasamy:Tribologicalbehaviourofpowder

metallurgyprocessed aluminium hybridcomposites with the addition of graphite solidlubricant,CeramicsInternational,Vol.39,No.2,

pp.11691182,2013.

[6] S.Basavarajappa,G.Chandramohan,K.Mukund,M.Ashwin,M.Prabu:Dryslidingwearbehaviorof Al 2219/SiCpGr hybrid metal matrixcomposites,JournalofMaterialsEngineeringand

Performance,Vol.15,No.6,pp.668674,2006.

[7] S. Basavarajappa, G. Chandramohan: Dry slidingwear behavior of hybridmetalmatrix composites,MaterialsScience,Vol.11,No.3,pp.253257,2005.

[8] S. Basavarajappa, G. Chandramohan, A.Mahadevan: Influenceofslidingspeedonthedrysliding wear behaviour and the subsurfacedeformation on hybridmetalmatrix composite,

Wear,Vol.262,pp.10071012,2007.

[9] S.Mahdavi, F.Akhlaghi:EffectofSiCcontentonthe processing, compaction behavior, andproperties of Al6061/SiC/Gr hybrid composites,

JournalofMaterialsScience,Vol.46,No.5,pp.1502

1511,2011.

[10]F.Akhlaghi,S.Mahdavi:EffectoftheSiCContenton

the

Tribological

Properties

of

Hybrid

Al/Gr/SiC

Composites Processed byIn SituPowderMetallurgy (IPM) Method, Advanced Materials

Research,pp.18781886,2011.

[11]S.Suresha,B.K.Sridhara:Wearcharacteristicsofhybrid aluminium matrix composites reinforced

with graphite and silicon carbide particulates,

Original Research Article, Composites Science

andTechnology,Vol.70,No.11,pp.16521659,2010.

[12]S. Suresha, B.K. Sridhara: Effect of addition ofgraphite particulates on the wear behavior in

aluminiumsilicon carbidegraphite composites,Materials&Design,Vol.31,pp.18041812,2010.

[13]S.Suresha,B.K.Sridhara: Effectofsiliconcarbideparticulates on wear resistance of graphiticaluminium matrix composites,Materials &

Design,Vol.31,No.9,pp.44704477,2010.

[14]S.Suresha,B.K.Sridhara: Frictioncharacteristicsof aluminium silicon carbide graphite hybridcomposites,Materials&Design,Vol.34,pp.576

583,2012.

[15]W.Ames,A.T.Alpas:Wearmechanismsinhybridcomposites of graphite20% SiC in A356aluminumalloy,Metall.Mater.Trans.A,Vol.26,pp.

8598,1995.


7/7


154

[16]A. Vencl, I. Bobic, S. Arostegui, B. Bobic, A.Marinkovic,M.Babic:Structural,mechanicalandtribologicalproperties ofA356 aluminium alloyreinforced with Al2O3, SiC and SiC + graphiteparticles,JournalofAlloysandCompounds,Vol.

506,pp.631639,2010.

[17]A. Vencl, I. Bobic, B. Stojanovic: Tribologicalproperties ofA356AlSi alloy composites under

dryslidingconditions,IndustrialLubricationandTribology,Vol.66,No.3,2014(inprint).

[18]J.Rodriguez,P. Poza,M.A.Garrido,A. Rico:Drysliding wear behaviour of aluminiumlithiumalloys reinforced with SiC particles, Wear, Vol.

262,pp.292300,2007.

[19]L.Jungmoo,K.Sukbong,H.Jianmin: Dryslidingwear of MAOcoated A356/ 20 vol.% SiCpcomposites in the temperaturerange25180 C,

Wear,Vol.264,pp.7585,2008.

[20]R.N.Rao, S.Das,D.P.Mondal, G.Dixit:Effectofheat treatmenton the slidingwearbehaviourofaluminium alloy (Al ZnMg) hard particlecomposite, Tribology International, Vol. 43, pp.

330339,2010.

[21]M. Gui, S.B. Kang:Dry slidingwear behaviorofplasmasprayed aluminum hybrid compositecoating, Metall. Mater. Trans., A Vol. 32A, pp.

23832392,2001.

[22]A.K. Mondal, S. Kumar: Dry sliding wearbehaviour of magnesium alloy based hybridcomposites in the longitudinal direction, Wear,Vol.267,pp.458466,2009.

[23]R.N.Rao,S.Das,D.P.Mondal,G.Dixit:Dryslidingwearbehaviourof casthigh strengthaluminium

alloy (AlZnMg) and hardparticle composites,Wear,Vol.267,pp.16881695,2009.

Wear Properties of A356/10SiC/1Gr Hybrid Composites in Lubricated Sliding Conditions

Documents

Transcript of Wear Properties of A356/10SiC/1Gr Hybrid Composites in Lubricated Sliding Conditions