published_or_final_version / Electrical Engineering / Master / Master of Philosophy

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This master thesis report evaluatesthe lubricating effect of graphene (G)and graphene oxide (GO). Thesematerials have been added, in particlecondition, in Ag-based slidingcontacts and lubricating greases. Thework focuses on the tribologicalevaluation of these materials,especially friction, wear and contactresistance analyses. The friction andwear behaviors of Ag-based contactscontaining of a wide concentrationrange of graphene and graphene oxideare tested against pure silver using atest load of 2 and 10 N at a constantspeed of 5 cm/s. It was revealed thatsmall amounts of G and GO are able tosignificantly reduce the frictioncoefficient and wear rate. Contactresistance measurements revealed thatresults similar to pure Ag can beachieved with G content up to 10vol%.Possible mechanisms, which maycontribute to this tribologicalbehavior are the Ag-C interactions andthe lubricating nature of graphene.Friction tests with G and GOcontaining lubricating greases showinconsistent results, and both greasesand corresponding test methods forevaluation require furtheroptimization. The overall, promising,tribological behavior of G and GOholds for the implementation invarious industrial applications. Thereis no doubt that these kinds ofmaterials can play an important rolein ABBs future work. This masterthesis report shows yet anotherapplication area for theseextraordinary materials.

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Nitric oxide (NO) has become a molecule of interest in biological research. NO is generated via the oxidation of L-arginine, by NO synthase (NOS), and plays a key role in many bioregulatory systems, including smooth muscle relaxation, platelet inhibition, neurotransmission, and immune stimulation, primarily through the formation of cGMP. N-Diazeniumdiolates (NONOates) are an interesting class of compound that can deliver NO specifically to a target site, with potential biological or therapeutic value and minimal side effects. The versatility of NONOates makes them ideal for studying NO in many different scenarios. Primary amine diazeniumdiolates such as isopropyl amine (IPA/NO) can release HNO under physiological conditions.\\Quantitative Structure Activity/Property Relationships (QSAR/QSPR) relate the structure of a compound, to a property/activity of interest ( biological activity). QSAR/QSPR studies are of great importance in drug design. Model that predict the half-lives of NONOates was built and were studied the influence of each variable on decomposition rate. External validation of this model will be made using new set of NONOates to test the Model.

Vibrational spectroscopy is used to elucidate the adsorption mechanisms of model volatile organic pollutants with a variety of mineral oxides. Vapor phase adsorption processes are particularly important in the vadose zone of an aquifer, where void spaces are filled with air and vapor transport is significant. Gaining a better understanding of the interactions occurring at the oxide-air interface is critical in developing or improving remediation strategies. In this work, Raman and infrared spectroscopy are used to obtain molecularly specific information concerning model pollutant-oxide adsorption processes. The choices of pollutants are varied to include several classes of compounds. The interactions of azaarenes, aromatics, chlorinated aromatics, trichloroethylene, and tributyl phosphate are investigated with several mineral types. Pure mineral phases such as silica, alumina, hydrated iron oxide, and montmorillonite clay are used to provide a basis set of interactions, which can be extended to more complex systems in the future. Pollutantoxide interactions, including weak physisorption, hydrogen bonding, Bronsted acid-base, and Lewis acid-base, were identified in this work and varied depending on the specific pollutant-oxide system. This research provides surface adsorption information on environmentally relevant contaminants and the techniques may be utilized to verify the accuracy of pollutant fate and transport models and to improve remediation strategies for such pollutants.

This dissertation has focused on the study of the ITO/organic heterojunction and the chemistries therein, it proposes appropriate strategies that enhance the interfacial physical and electronic properties for charge injection with application to organic thin-layer devices. We focused on four major aspects of this work: i) To characterize the ITO surface and chemistries that may be pertinent to interaction with adjacent organic layers in a device configuration. This developed a working model of surface and provided a foundation for modification strategies. Characterization of the electronic properties of the surface indicate less than 5% of the geometrical surface is responsible for the bulk of current flow while the rest is electrically inactive. ii) To determine the extent to which these chemistries are variable and propose circumstances where compositional changes can occur. It is shown that the surface chemistry of ITO is heterogeneous and possible very dynamic with respect to the surrounding environment. iii) To propose a strategy for modification of the interface. Modification of ITO surfaces by small molecules containing carboxylic acid functionalities is investigated. Enhancements in the electron transfer rate coefficient were realized after modification of the ITO electrode. The enhancements are found to stem from a light etching mechanism. Additionally, an elecro-catalytic effect was observed with some of the modifiers. iv) Apply these modifications to organic light emitting diodes (OLEDs) and organic photovoltaic devices (OPVs). Enhancements seen in solution electrochemical experiments are indicative of the enhancements seen for solid state devices. Modifications resulted in substantially lower leakage currents (3 orders of magnitude in some cases) as well as nearly doubling the efficiency.An additional chapter describes the creation and characterization of electrochemically grown polymer nano-structures based on blazed angle diffraction gratings. The discussion details the micro-contact printing process and the electro-catalytic growth of the conductive polymers PANI and PEDOT to form diffraction grating structures in their own right. The resulting diffraction efficiency of these structures is shown to be sensitive to environmental conditions outlining possible uses as chemical sensors. This is demonstrated by utilizing these structures as working pH and potentiometric sensors based on the changing diffraction efficiency.

Research was performed on the development of metal-supported solid oxide fuel cell (SOFC) electrolytes by suspension and solution precursor plasma spraying (SPS and SPPS). Experiments were conducted to understand the effects of many plasma-, feedstock-, and substrate-related process parameters on the microstructure, permeability, and conductivity of the resulting coatings. Most work was performed with yttria-stabilized zirconia (YSZ), but samaria-doped ceria (SDC) was also considered. The plasma-to-substrate heat flux behaviour of the process is particularly relevant for producing dense electrolytes with low segmentation cracking. Heat flux profiles for various processing conditions were experimentally determined and then used to model temperature distributions in the electrolyte and substrate during deposition. The results showed a strong correlation between segmentation crack severity and the peak temperature difference between the electrolyte surface and the metal support during deposition. Building on these findings, two strategies were developed for improving electrolyte performance. The first strategy is to use a bi-layer electrolyte structure, in which one layer is dense but has segmentation cracks and the other layer is more porous but contains relatively few segmentation cracks. A cell with a bi-layer electrolyte achieved a peak power density of 0.718 W cm-2 at 750 °C using hydrogen as fuel. The second strategy involves reducing the thickness and roughness of the electrode on which the electrolyte is deposited, which first required the development of improved metal supports. A thinner electrode reduces the thermal stresses that drive segmentation cracking and a smoother surface minimizes the formation of concentrated porosity. A cell with a 16 μm thick anode and a 21 μm thick electrolyte achieved an open circuit voltage (OCV) of 1.053 V, a series resistance of 0.284 Ω cm2, and a peak power density of 0.548 W cm-2 at 750 °C using hydrogen as fuel. A separate cell with a 28 μm thick electrolyte achieved an OCV of 1.068 V. At the end of the thesis, cell performance is compared to that of state-of-the-art cells produced in other facilities and using other production methods.