Beaber, Aaron Ross2011-10-122011-10-122010-08https://hdl.handle.net/11299/116585University of Minnesota Ph.D. dissertation. August 2011. Major: Chemical Engineering. Advisors: William W. Gerberich, Steven L. Girshick. 1 computer file (PDF); viii, 180 pages.Coatings with high wear resistance have generated a great deal of interest due to a diverse range of applications, including cutting tools, turbine blades, and biomedical joint replacements. Ceramic nanocomposites offer a potential combination of high strength and toughness that is ideal for such environments. In the current dissertation research, silicon and silicon carbide based films and nanostructures were deposited using a hybrid of chemical vapor deposition and nanoparticle ballistic impaction known as hypersonic plasma particle deposition (HPPD). This included SiC/Ti-based multilayers and Si-SiC core-shell composite nanotowers. Using a combination of nanoindentation and confocal Raman microscopy, the role of plasticity and phase transformations was studied during fracture events at small length scales. In a parallel study, HPPD synthesized Si nanospheres and vapor-liquid-solid (VLS) Si nanotowers were compressed uniaxially inside the TEM. These experiments confirmed inverse length scale dependent relationships for strength and toughness in Si based on dislocation pile-up and crack tip shielding mechanisms, respectively. A transition was also identified in the deformation of Si under anisotropic loading below a critical size and used as the basis for a new toughening mechanism in Si-SiC composites. Overall, these results demonstrate the importance of nanoscale confinement and localized stress in the design of mechanically robust nanocomposites.en-USFracture toughnessin situ indentationNanocompositeSiliconSilicon carbideSize dependent deformationChemical EngineeringThesis or Dissertation