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A High-Throughput Study of the Tribological Properties of MoN-Cu Coatings in Low Viscosity FuelsCaldwell, Slater Leigh 07 1900 (has links)
The aim of this thesis is to develop a tribocatalytically active solid coating that exhibits strong wear resistance, while also inducing the formation of carbon-based tribofilms when used in a hydrocarbon environment. By using tribocatalytic MoN-Cu synthesized through combinatorial DC reactive magnetron co-sputtering, a gradient between MoN and Cu is deposited and used to determine an ideal Cu composition exhibiting high wear resistance and the formation of a carbon-based tribofilm. To determine the properties of the thin film, various characterization methods were used before and after wear tests from an Anton-Paar pin-on-disk tribometer in a decane or ethanol bath. XRD, SEM, and EDS determined the phase structures and compositions. Nanoindentations and optical profilometry found hardness, Young's modulus, and wear rates. Raman analysis saw carbon presence on the surface of the wear tracks, confirming the formation of carbon tribofilms. For the wear rates, it was found that each fuel had different reactions to the changing Cu at%. From the Raman data, carbon presence, wear rates, and Cu at% did not reveal a strong correlation between the three sets of information. Specifically for the ethanol tracks, the was a connection between a high carbon amount and lower wear rate. It was inconclusive if there was one Cu at% that afforded the most ideal conditions. The information found here has developed the knowledge of MoN-Cu as a solid protective coating, and for using combinatorial DC reactive magnetron co-sputtering as an aid for materials development.
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Mechanically Driven Reconstruction of Materials at Sliding Interfaces to Control WearShirani, Asghar 05 1900 (has links)
To minimize global carbon emissions, having efficient jet engines and internal combustion engines necessitates utilizing lightweight alloys such as Al, Ti, and Mg-based alloys. Because of their remarkable strength/weight ratio, these alloys have received a lot of attention. Nonetheless, they have very poor tribological behavior, particularly at elevated temperatures beyond 200 °C, when most liquid lubricants begin to fail in lubrication. Over the last two decades, there has been a lot of interest in protecting Al, and Ti-based alloys by developing multiphase solid lubricants with a hard sublayer that provide mechanical strength and maintain the part's integrity while providing lubricity. The development of novel coatings with superior lubricity, high toughness, and high-temperature tolerance remains a challenging and hot topic to research and provide new engineered solutions for. To address and provide solutions to protect light-weight, i.e., Al, and Ti alloys at high-temperature and bestow superior tribological properties to such alloys, three types of adaptive lubricious coatings have been studied in this thesis: Nb-Ag-O self-healing lubricious ternary oxide, PEO-chameleon a self-adaptive multi-phase coating, and Sb2O3-MSH-C lubricious adaptive coatings to address this challenge. The development of the Nb-Ag-O ternary resulted in a coefficient of friction as low as 0.2 at 600 °C and crack healing at 900 °C. PEO-chameleon coatings demonstrated a remarkably low COF, as low as 0.07 at 300 °C and 1.4 GPa applied pressure. Finally, the Sb2O3-MSH-C multi-phase lubricious solid lubricant revealed superlubricity, with a CoF of 0.008 at 300 °C, providing a potentially promising contender for high-temperature, high-load applications.
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