Proceedings of SerbiaTrib '13

figure 3a it could be seen that the wear of thecomposite with 2 wt% of graphite is almostnegligible under appliedload of 10N.Seah et al. [24] have confirmedthat the wearrate of as-cast ZA-27/graphite particulate decreasesmonotonically with an increase in sliding speed, , butin our caseit is inversely because of differentcontact geometry.portion of the contact surface. Presence of thegraphite film inn contact zone reduces the t metal-to--during drysliding,themetal/graphiteecompositestribo-influenced the graphitefilmm forming onthe contacttsurface of elements [18–20], whichacts as solidlubricantthatreducesmetal-to-metallcontactbetweenn the sliding surfaces. The formationof graphiterichlubricant film between the slidingsurfaces has beenexplainedd as a resultt of the softsecond phase (graphite)squeezing-out from thesubsurface toward the mating surfacedue toextensive plastic deformation metal contact between the sliding pairs.Many researchers have reported that[18].4.CONCLUSIONa)b)Based on the results presented in this t paper itcould be concluded: Generally wear w volumee of the composites arelesser in comparison to o the unreinforced matrixalloy. Higher content of graphite particles within thematrix alloyy results in higher wear resistance r ofmaterial, composite with 2 wt% of graphiteparticles has lesser values of wearr volumes incomparisonn to the composite with 1wt% ofgraphite particles, p under the same contacttconditions. Wear volume of all tested specimens increasesswith slidingg speed and normal load increase. Higher wear resistance of ZA27/graphitecomposites in comparison to the unreinforcedmatrix alloyy is a result of graphite film f formingon the surface of contact elements.ACKNOWLEDGEMENTTThestudy was financed byy Ministry of Education,Science and TechnologicaTal Development, Serbia,project No.35021.c)Figure5. Wear scars of tested specimens: a)unreinforced matrix alloy; b) and c) composites withh 1and 2 wt% of graphite particles, respectively.Figure 5 presents wear scarss of all testedspecimens Based on the wear scars it couldd beconcluded that the dominant wear mechanism wasabrasive wear, because of this parallel tracks withinthe wear scars of all tested materials. One canclearly notice that on the worn surface the blackgraphite film is smeared and it covers the large13 th International Conference on Tribology – Serbiatrib’13REFERENCES[1] Vasiliev, V.V., V Morozov, E.V.: Mechanics andAnalysis of Composite Materials. Elsevier, Oxford,2001.[2] Pruthviraj, R.D., R Krupakara, P.V.: Influence of SiCadditions onn mechanical l properties of the Zn–Alalloy (ZA-27). Int J Mater Sci 2(1) ), pp. 53–57,2007.[3] Babic, M., Ninkovic, R., Rac, A.: Sliding WearBehavior of o Zn-Al Alloys in Conditions ofBoundary Lubrication. L The Annals of University‘‘Dunarea De Jos’’ of Galati Fascicle VIII.Tribology, pp. p 60–64, 2005.[4] Babic, M., Mitrovic, S., Dzunic, D., Jeremic, B.,Bobic, I.: Tribological behavior of composites based127