Film thickness decreased with increasing the concentration of CuO. Therefore, the dark regions represent the deposition of CuO nanoparticles on the get in touch with surfaces. This deposition can compensate for the mass loss around the speak to surfaces by the “mending effect”. This mechanism of CuO nanoparticles was reported in previous research, where CuO nanoparticles have been utilised as an additive in VBIT-4 Protocol synthesis oil [25]. In the tests lubricated with ZnO, the color in the center of interferometric photos was discovered to be fairly related to that with the test with pure IL. It suggests that ZnO combined together with the IL didn’t drastically have an effect on the tribofilms’ properties formed by the IL. On the other hand, because the concentration of zinc oxide nanoparticles increased, colored places appeared around the put on surface with the ball that have been diverse from the colour of tribofilms formed by the IL. The improve in the tribofilms’ thickness inside the test of IL 0.five wt ZnO was shown by the darker colors in the interferometric photos.D-Fructose-6-phosphate disodium salt manufacturer Figure 7. Cont.Components 2021, 14,9 ofFigure 7. Series of interference photos for various concentrations of nanoparticles just after rising rubbing time: (a) IL, (b) IL 0.two wt CuO, (c) IL 0.five wt CuO, (d) IL 0.2 wt ZnO, and (e) IL 0.5 wt ZnO.three.3. Surface Analysis Chemical components on disc surfaces soon after the put on test were analyzed by SEM/EDX at 3 areas, which includes unwear surfaces, scratches, and defects. Before any test of surface evaluation, the specimens had been cleaned with ethanol in an ultrasonic bath. Figure 8 shows an SEM image and EDX analysis outcomes in the unwear surface. Though the unwear surface was not abraded by the speak to involving the ball and disc, the appearance in the fluorine element from the [N1888] [NTf2] showed that chemical reactions may possibly occur among the [NTf2] anion and the metal surfaces upon heating. The chemical element fluorine might have an effect on the corrosion approach around the metal surfaces depending on its concentration [36].Materials 2021, 14,10 ofFigure 8. (a) SEM image and (b) EDX analysis of your unwear surface around the disc.SEM/EDX surface evaluation in the rubbed surfaces on discs in the tests lubricated with all the IL and different concentrations of CuO and ZnO nano-oxides are shown in Figure 9. The chemical composition of worm surfaces on the disc was analyzed at two different points, defects, and scratches. The survey spectra plus the weight percentages of chemical compositions on the defects are represented by the figures on the appropriate side from the corresponding SEM images. The distribution of chemical elements on the scratch line for all tested lubricants is summarized in Table 4.Figure 9. Cont.Materials 2021, 14,11 ofFigure 9. SEM micrographs of worn surface (left) and EDX analysis of defects (proper) for the tests lubricated with the IL and different concentrations of nanoparticles: (a) IL, (b) IL 0.two wt CuO, (c) IL 0.five wt CuO, (d) IL 0.2 wt ZnO, and (e) IL 0.five wt ZnO.Each of the oxide nanoparticles exhibited unique lubrication mechanisms when they have been added for the [N1888] [NTf2]. The presence of copper within the EDX results, shown in Figure 9b,c and Table 4, indicates that the CuO nano-oxide reacted with the IL and deposited on the surfaces in get in touch with. An instance of a chemical reaction of CuO with a water-free [NTf2] anion-based IL was represented within the perform [37]. The authors pointed out that CuO could effectively be dissolved inside the water-free IL upon heating to 175 C for 24 h. Because the wear test condit.
