Proceedings of SerbiaTrib '13

The influence of the sliding speed on wearvolume for both materials is shown in Figure 7, fordifferent values of normal loads.The effects of the normal load on wear volumeof both composite and alloy is presented inFigure 8, for different values of sliding speeds andfor sliding distance of 300 mWear, mm 3 x10 -314001200100080060040020000 5 10 15 20 25 30 35Figure 8. Wear volume of ZA27/5%SiC/3%Gr compositeand ZA27 alloy depending on contact loads, for differentsliding speeds and for sliding distance of 300 m.Analytical and graphical variations in wear ratedue to changes of sliding speeds and normal loadsin dry sliding conditions are presented in Figures 9and 10. Exponential regression functions wereadopted. Corresponding regression functionscoefficients and curvilinear correlation indices wereobtained showing the good correlation betweenexperimental data and used empirical distributions.Wear rate of ZA27 alloy in dry slidingconditions is presented in Figure 9 and wear rate ofZA27/5%SiC/3%Gr composite in dry slidingconditions is shown in Figure 10. Variations of thewear rate as a function of the sliding speed andnormal load are graphically presented for the ZA27alloy and composite materials.Both tested materials share basically the samenature of wear process development in all contactconditions. The observed composite material hasbetter wear resistance, under the same test conditions.I, mm 3 /m x 10 -3432100.4ZA27, v1=0.25 m/sZA27, v2=0.5 m/sZA27, v3=1 m/sComposite, v1=0.25 m/sComposite, v2=0.5 m/sComposite, v3=1 m/s0.6v, m/s0.81ZA2710s = 300 mLoad, NFigure 9. Wear rate of ZA27 alloy in dry slidingconditions.1520Fn, N25304.44.243.83.63.43.2I, mm 3 /m x 10 -3Figure 10. Wear rate of ZA27/5%SiC/3%Gr compositein dry sliding conditions.The comparative histograms of the wear volumeformed after 300 m of sliding distance, dependingon the contact conditions (the sliding speed and thenormal force) for the basic ZA27 alloy andZA27/5%SiC/3%Gr composite materials are shownin Figure 11.Wear, mm 3 x 10 ‐31400120010008006004002002.51.50.5032100.40.6v, m/sZA27ZA27/5%SiC/3%GrZA27+5%SiC+3%Gr0.8110Figure 11. Comparative histograms of wear volume ofZA27 alloy and ZA27/5%SiC/3%Gr composite.Analysis of histograms in Figure 11 shows that atrend of increase of wear with the increase of normalload may be observed. The increase of sliding speedinduces also the increase of wear. This observation isvalid for both tested materials. It may be noticed thatthe wear of the tested ZA27 alloy is alwayssignificuly higher compared to wear of thecomposite with addition of the SiC and graphiteparticles.From the Figure 11, the influence of the normalload and sliding speed on the wear magnitude maybe clearly noticed. The wear rate increases both withthe increase of the normal force the increase of thesliding speed. The largest value of wear correspondsto the highest sliding speed (v 3 = 1 m/s) and to thehighest value of the normal contact load (F 3 = 30 N).For the lowest sliding speed (v 1 = 0.25 m/s) and thelowest load (F 1 = 10 N), the smallest wear valueswere recorded.Characterization of the microstructure of wearsurface for metal matrix composites is morecomplex than that of the metals or alloys and anunderstanding of wear mechanisms is far from1520Fn, Nv1‐F1 v1‐F2 v1‐F3 v2‐F1 v2‐F2 v2‐F3 v3‐F1 v3‐F2 v3‐F325302.82.62.42.221.81.61.41.21144 13 th International Conference on Tribology – Serbiatrib’13