Proceedings of SerbiaTrib '13

μm, compared with Figure 17, wich shows theeffect of running on the wear behaviour of surfacewith R a = 0.045 μm.A63A64Figure 16. The effect of running-in on the wearbehaviour of the surface with R a = 0.015 μm, t = 5 min,Pr 998. The bush from previous determination was used.A65A67A69A66A68A70Figure 17. The effect of running-in on the wearbehaviour of the surface with R a = 0.045 μm, t = 5 min,samplez 999, (new bush) 1000 and 1001 (with the bushfrom previous determination).Different roughness used has caused not only adifference between worn volume values, but also inthe aspect of wear imprint (wear type). In the caseof surfaces with R a = 0.015 μm, R a = 0.075 μm, (t=3 sec.) and R a = 0.19 μm, (t =3 sec.), the wear is ofadhesive type (metallic shape with pronouncedscars). In case of surfaces with R a = 0.045 μm,oxidative wear type is prevailing. While reducingthe wear rate as a result of surface compliance,surfaces with R a = 0.075 μm and R a = 0.19 μm alsogo in oxidative wear regime.In the case of super-finished surfaces, with R a =0.015 μm and R a = 0.045 μm, a favourableinfluence of running in is not observed.For rouhness R a = 0.015 μm, R a = 0.075 μm andR a = 0.19 μm, the results obtained for the volume ofworn material, are consistent with the strain ofcontact, determined by the lubricant film parameterh min / σ.For surfaces with rouhness R a = 0.045 μm, therewas observed a running-in influence. After the first5 minutes of operation, the entire contact surface iscovered with oxide. The imprint obtained afteranother 5 minutes, with the same bush, has aparticular form, oxidative wear area restricting thehalf at outcome of the loaded area (sample 1001).It follows that after running-in, lubricationconditions improve.In the case of super-finished surfaces, afavourable influence of running-in is not observed.4.2. Influence of initial roughness on the wearand friction coefficientSurface wear, a quantity determined by thefraction of area in contact, should be a monotonefunction of film parameter h / σ. The minimumvalue of wear should coincide with the minimumvalue of surface roughness.A large number of determinatons of wear, withfour roughness have been made: R a = 0.015 μm;R a = 0.045 μm; R a = 0.075 μm si R a = 0.19 μm.Mean values of volume of worn material for thefour roughness are:R a = 0.015 μm→V u = 7.0 x10 -5 mm 3 → μ = 0.038;R a = 0.045 μm→V u = 7.0 x10 -6 mm 3 → μ = 0.050;R a = 0.075 μm→V u = 3.7 x10 -5 mm 3 → μ = 0.038;R a = 0.190 μm→V u = 1.0 x10 -3 mm 3 → μ = 0.078.Simultaneously with the surface wear, thefriction coefficient was also measured.In Fig. 18 reprezentative images for three of thefour roughnesses are presented.A75A79A81A76A80A82Figure 18. The effect of running-in on the wearbehaviour of the surface with R a = 0.015 μm, t = 5 min,Pr 998. S-a folosit bucsa de la determinarea precedenta.13 th International Conference on Tribology – Serbiatrib’13 339