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Title: Investigations of the frictional behaviour of nanotextured surfaces by friction force microscopy
Author: Quignon, Benoit
ISNI:       0000 0004 5915 4581
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2015
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Friction is omnipresent in our daily life, and although this phenomenon has been studied for centuries, the fundamental understanding on tribological processes as a whole is still lacking. Reducing friction is beneficial in many applications, from mediating wear to improving the life span of devices, hence improving our knowledge of the parameters affecting frictional forces is of paramount importance. In particular, the miniaturisation of modern devices implies that their reliability and durability become friction limited. Recent advances in the fabrication of nanostructured surfaces with tuneable topographic properties, along with advances in metrological tools such as the atomic force microscope (AFM), now provide the means to systematically study friction on well-defined nanostructured surfaces. This research project is focused on the lubricated and un lubricated frictional behaviour of nanotextured surfaces using the AFM with conventional and colloidal probes. The frictional properties of nanotextured surfaces bearing aluminium oxide nanodomes and zinc oxide nanorods of varying topographic properties in air, as well as the frictional properties in aqueous solutions of ionic and nonionic surfactants on flat and textured surfaces of titanium oxide, are reported. The results show that for the nanodomed-textured surfaces, the ancient Amontons laws of dry friction are obeyed; however, the friction coefficient was insufficient to fully characterise the frictional behaviour of such nanotextured surfaces. Pronounced stick-slip frictional characteristics were observed, with the amplitude of the stick-slip varying linearly with the applied load. On nanorod-textured surfaces, the friction-applied load linear relationship was however lost, due to the bending contributions of the rods to the lateral force experienced by the probe. Finally, the results obtained on flat and pillar-textured titanium oxide surfaces showed that ionic surfactants could mediate effective boundary lubrication with the existence of two frictional regimes, due to load- and shear-induced structural changes in the nanofilms of the adsorbed surfactant molecules.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available