Browsing by Subject "Wear"
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Item Open Access Effect of triboelectric charges on friction and wear of polymers at macro scale(2017-12) Sayfidinov, KhaydaraliThe interest towards the study of underlying mechanism behind tribology has gained enormous attention recently since almost one-fourth of the total produced global energy is consumed by friction and wear. Dry sliding or rubbing two dielectric polymers on each other results in surface charging showing significant effects on friction coefficients and wear. Determination of the correlation between triboelectricity and tribologic events like friction and wear, the control of friction coefficient, and reducing wear by surface charging constitutes the main idea and research topic of this thesis. However, tribological events are very complicated considering the fact that diverse processes encompassing of physical and chemical changes occur at the counterface. Therefore, the fundamentals of friction is still controversial. Owing to tribological actions that occur due to contact between different phases of the matter, interfaces generate tribocharges due to electron, ion, and material transfer mechanisms. Even though the fundamental mechanism is still vague and under debate, it is believed that static electrification due to tribological actions are utterly because of electron transfer. Current studies unveiled that physical based phenomena are not the only source of surface electrification but also chemical changes such as bond rupturing and following surface oxidation that can take place as a result of mechanical actions on an insulating polymer. Consequently, these two groups of surface events; surface electrification and friction are expected to demonstrate a mutual relation, and detailed study concerning this relation needs to be investigated in order to solve e.g. energy loss and wear problems in tribology. To achieve this goal, it is essential to understand the main mechanisms and processes involved, and reveal the connections between tribological events and establish a relationship between all the intrinsic and extrinsic properties of materials from molecular, nano to meso scale. Thus, in this study, we investigated the contribution of triboelectrification to friction by taking into account some factors - surface area, load, atmosphere - between common polymers and pure cellulose under dry friction conditions.Item Open Access Nano patterning of AISI 316L stainless steel with nonlinear laser lithography: sliding under dry and oil-lubricated conditions(Elsevier Ltd, 2016) Gnilitskyi, I.; Rotundo, F.; Martini, C.; Pavlov, I.; Ilday, S.; Vovk, E.; Ilday, F. Ö.; Orazi, L.Femtosecond laser-based Nonlinear Laser Lithography (NLL) was applied to AISI 316L stainless steel, which requires surface modification to achieve satisfactory tribological behaviour. NLL advances over the well-known Laser Induced Periodic Surface Structures (LIPSS) in terms of uniformity and long-range order of high speeds, over large areas. A galvanometric scanner head was used for an high production rate. Dry and lubricated sliding tests, considering different orientations of the nanotexture showed that COF values after NLL treatment are significantly lower. In lubricated tests, COF values of NLL-treated surfaces are nearly half the values of untreated surfaces, whereas the difference further increases when measured in dry conditions, where the orientation of the surface texturing influences the results.Item Open Access Synthesis, characterization, and wear and friction properties of variably structured SiC/Si elements made from wood by molten Si impregnation(2012) Dhiman, R.; Rana, K.; Bengu, E.; Morgen P.We have synthesized pre-shaped SiC/Si ceramic material elements from charcoal (obtained from wood) by impregnation with molten silicon, which takes place in a two-stage process. In the first process, a porous structure of connected micro-crystals of β-SiC is formed, while, in the second process, molten Si totally or partly infiltrates the remaining open regions. This process forms a dense material with cubic (β-)SiC crystallites, of which the majority is imbedded in amorphous Si. The synthesis of preshaped "sprocket" elements demonstrates that desired shapes of such a dense SiC/Si composite ceramic material can be achieved, thus suggesting new industrial applications. The structure and composition of numerous as-synthesized samples were characterized in detail by using a wide range of techniques. Wear and friction properties were also investigated, with polished samples. The properties found for the present samples are very promising for abrasive applications and for new generation brake systems. © 2011 Elsevier Ltd.