| Abstract: | Recently, there has been an increase in research in the application of ionic liquids containing nanoparticles as lubricants due to their properties such as thermally stability, non-volatility and non-flammability. The purpose of this thesis is to describe the tribological and rheological properties of mixtures of nanoparticles (NPs) and ionic liquids (ILs), specifically the mixture of bare SiO₂ (silica) nanoparticles and ionic liquid 1-butyl-3-methylimidazolium (trifluoromethysulfony)imide and the mixture of SiO₂ nanoparticles functionalized by octadecyltrichlorosilane (OTS) and ionic liquid1-butyl- 3-methylimidazolium (trifluoromethysulfony)imide. Functionalized SiO₂ nanoparticles dispersion in ionic liquid was compared to that of the bare SiO₂ nanoparticles, and shown that functionalized SiO₂ nanoparticles led to improved colloidal stability. Friction force profiles, friction coefficients, viscosity behavior, wear behavior of these mixtures at various nanoparticles concentrations for a tribo-pair of stainless steel ball and a steel surface were also investigated. It was shown that the friction coefficient of the OTS functionalized SiO₂ nanoparticles for the optimum concentration (0.1 wt.%) was 36% less than that of the pure ionic liquid, while the friction coefficient of the bare SiO₂ nanoparticles and the ionic liquid mixture at the optimum concentration (0.05 wt.%) was 23% less than that for the pure ionic liquid. Moreover, friction surfaces of the two kinds of silica nanoparticles at the optimum concentration were examined by scanning electron microscopy (SEM) and friction traces. Eventually, it has been shown that promising tribological properties of ionic liquids can be further enhanced by incorporating bare SiO₂ nanoparticles into ionic liquids. Moreover, the tribological performance of the mixture of the OTS functionalized SiO₂ nanoparticles and ionic liquid could be better than that of the mixture of bare SiO₂ nanoparticles in the same ionic liquid. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/152662 |
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