Show simple item record

dc.contributor.advisorBaykara, Mehmet Zeyyad
dc.contributor.authorDemirbaş, Tuna
dc.date.accessioned2016-07-01T11:12:11Z
dc.date.available2016-07-01T11:12:11Z
dc.date.issued2015
dc.identifier.urihttp://hdl.handle.net/11693/30092
dc.descriptionCataloged from PDF version of article.en_US
dc.description.abstractTo extend the lifespan of mechanical systems, wear and friction must be minimized with the utilization of lubricants. On the other hand, traditional fluid-based lubrication schemes fail in nano- and micro-scale systems due to increasing surface-to-volume ratios and associated physical effects. As such, research efforts in recent years have been aimed at characterizing the structure and mechanical properties of various candidates for solid lubricants. Due to its outstanding electronic and mechanical properties, the two-dimensional “wonder material” graphene has been the focus of a large variety of experiments in the past decade. Based on its promise as a single-layer solid lubricant suitable for use in nano- and micro-scale systems, the nanotribological properties of graphene have been investigated in several studies in the literature. While frictional characteristics of mechanically exfoliated graphene samples as a function of layer number have been related to the effect of puckering, the nanotribological behavior of graphene samples grown by chemical vapor deposition (CVD) is still under investigation. Considering that high quality graphene of sufficient dimensions for practical applications is currently grown by CVD and requires transfer from metal foils onto various substrates, the need for an extensive understanding of the nanotribological properties of such graphene samples arises. Based on the discussion above, this M.S. thesis presents a comprehensive structural and nanotribological characterization of CVD-grown graphene transferred onto oxidized silicon substrates (SiO2/Si). In particular, the processes of sample preparation and post-preparation transfer onto SiO2/Si substrates are optimized via a series of experiments. Advanced microscopy techniques are utilized for the structural and morphological characterization of the obtained graphene films. In particular, optical microscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM) are used to inspect graphene coverage on the substrate and associated structural features. On the other hand, Raman spectroscopy is employed to confirm the single-layer character of CVD-grown samples. The nanotribological properties of CVD-grown graphene samples on SiO2/Si are studied by AFM in the friction force microscopy (FFM) mode under ambient conditions by measuring the evolution of friction force with increasing normal load. The effect of using different probe tips, growth conditions, and post-transfer cleaning procedures on frictional behavior is evaluated. A comparison of lubrication performance with mechanically-exfoliated graphene is also performed. Results indicate that CVD-grown graphene acts as a very good solid lubricant on SiO2/Si, reducing coefficients of friction by ~90% for all investigated samples. It is shown that as-transferred CVD-grown graphene exhibits the highest mean lubrication performance and that the associated values drop slightly with post-transfer cleaning. Finally, the effect of wrinkles associated with CVD-grown graphene on measured friction values are quantitatively evaluated, with results revealing a substantial increase in friction on these structural defects.en_US
dc.description.statementofresponsibilityDemirbaş, Tunaen_US
dc.format.extentxv, 77 leaves, illustrations, charts, photographsen_US
dc.language.isoEnglishen_US
dc.rightsinfo:eu-repo/semantics/openAccessen_US
dc.subjectGraphene, Nanotribologyen_US
dc.subjectNanotribologyen_US
dc.subjectChemical vapor depositionen_US
dc.subjectAtomic force microscopyen_US
dc.subjectFriction force microscopyen_US
dc.subject.lccB121421en_US
dc.titleNanotribological properties of graphene grown by chemical vapor deposition and transferred onto silicon oxide substratesen_US
dc.typeThesisen_US
dc.departmentGraduate School of Engineering and Scienceen_US
dc.publisherBilkent Universityen_US
dc.description.degreeM.S.en_US
dc.identifier.itemidB121421


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record