The objective of this study is to investigate the interaction between a lightning strike and carbon/fiber composites. The first approach is to characterize the damage development in a composite structure subjected to simulated lightning strikes. Several existing studies have acknowledged that the lightning induced damaged can be categorized into two separate domains of damage; a primary domain of damage that occurs at the attachment point, and a secondary domain of damage that is typically formed around the attachment point. Quantitative studies of the causes of the primary damage domain are not satisfactory for explaining the secondary damage domain and thus, these two domains are produced by presumably different mechanisms. There have been many reports and studies focused on the inspection of the primary damaged area. However, the secondary domain of damage has not yet been fully explained and understood. An experimental setup was configured with a recommissioned lightning current simulator to generate artificial lightning strikes consistent with the existing standard for lightning protection testing used in the aerospace industry. Carbon/epoxy composite laminates in various layups and Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) panels were subjected to high impulse currents of different magnitudes. The lightning induced damage to the protected and non-protected composite laminates and PRSEUS panels were evaluated, and the influence of different variables such as current magnitude, strike location, and laminate layup were studied. An interesting observation was the secondary damage area that expanded laterally beyond the intense damage area. The structure of a composite panel is such that it forces the current to flow along the carbon fibers directions, as opposed to metals where the relatively isotropic conductivity of the metal allows current to distribute radially. It is argued in this work that the secondary domain of damage may be related to the anisotropic electrical conductivity property of the composite panels. A comprehensive theory based on multidimensional electromagnetic field simulation was proposed to reveal the root cause mechanisms of the unique patterns of secondary damage in the carbon composite structural materials tested with simulated lightning current impulses.

Recently, 3D printing has received increasing attention for the fabrication and assembly of electrodes for batteries due to the freedom of creating structures in any shape or size, porosity, flexibility, stretchability, and chemistry. Particularly, zinc ion batteries (ZIBs) are favored due to high safety, cheap materials cost, and high volumetric capacity (5,849 mAh/cm3), however, rapid evaporation of Zn due to low melting temperature has limited its 3D printability via conventional laser-based additive manufacturing technique. Here, we develop a printable ink for the fabrication of flexible and 3D printed Zn anode with varied surface areas using the direct ink writing (DIW) method. Our 3D printed porous and high surface area Zn anode structures effectively suppressed the dendrite growth while providing high Zn ion diffusion towards the cathode to significantly enhance the performance of ZIB. By varying filament distancing and path, we 3D printed zinc anode structures with different active surface areas, surface area to volume ratio, porosity, flexible and multiple layer structures that can be incorporated on any device. Carbon in the composite improved conductivity, and mechanical stability of 3D printed zinc anode. Our 3D printed composite anodes allowed flexible designing of batteries surpassing conventional battery designs such as coin cells or pouch cells and can be used to design printed energy storage systems.

<p> This report deals with the design of an electrode system which utilizes the double dis- charge technique to achieve a Uniform discharge between two continuous electrodes with the intent of using this electrode system as the excitation unit for a TEA CO2 laser. The particular electrode configuration dealt with in this report involves a continous cathode and a similar continuous anode which has a set of rounded tip, rod, preionization electrodes set into holes in it. Also included in this report is a preliminary measure of the gain of the resultant double discharge TEA CO2 laser. </p> / Thesis / Master of Science (MSc)

The work presented in this thesis can be divided into two research areas. First, two sets of organic-inorganic hybrid nanocomposites containing phenolic resin/trisilanolphenyl-POSS and phenolic resin/octa(aminophenyl)-T8-POSS nanocomposites were synthesized and the morphology and properties were investigated. Octa(aminophenyl)-T8-polyhedral silsesquioxane is an octafunctional-T8-POSS containing eight aniline-like amino groups, one on each corner silicon atom. It was synthesized in our laboratory by an improved two-step reaction sequence; nitration (HNO3) and reduction (HCOOH/Et3N). Varying amounts of POSS were codissolved with a resole phenolic resin in organic solvent. This was followed by solvent removal and thermal curing. Intermolecular interactions in these nanocomposites were probed by FT-IR. The micro-morphology and aggregation state of POSS were investigated using SEM, TEM, and WAXD studies. The thermal and mechanical properties and thermal stabilities of these composites were investigated by DMTA, DSC, and TGA. Second, two types of carbon-covered mono- and bimetallic (Sn, and Sn/Sb alloy) nanorods for use as anode materials in lithium ion batteries were synthesized by a thermal chemical vapor deposition method. Commercial antimony and tin oxide (Sb3O4/SnO2) nanopowders and added tin (IV) oxide (SnO2) nanoparticles (~19 nm) were used as the precursors for the growth of bimetallic Sn/Sb alloy and monometallic Sn nanorods, respectively. In addition, the shape of the products recovered were different when different hydrocarbon gas flow rates were used for growing intermetallic nanorods in carbon templates. Acetylene and methane were the gases tried. The morphologies and structures of the intermetallic nanorods in carbon templates were investigated using SEM and TEM and proved by X-EDS, XRD, and XPS studies.

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<p> In this thesis, the rate-limiting step is determined in a biofuel cell with a bio-anode, a Nation membrane and a conventional, platinum-based cathode using reference electrode method. It was discovered by surprise that the cathode overpotential dominated the cell overpotential. Na + in the membrane was found to hinder the W transport. The cathode overpotential increased due to the presence of Na + in the membrane and at the cathode. The limited H+ transport causes the increase of the cathode overpotential. H+ transport is the rate-limiting step in our biofuel cell, rather than commonly believed electron transport. Moreover, the cell power output degradation is not due to the conventionally believed depletion of the fuel substrate, inter-penetration of the fuel and oxidizer and the degradation of the biocatalysts, but the limited W transport in our biofuel cell. </p> <p> The existing oxygen reduction mechanism at the cathode was questioned and revised. When Na+ occupies all sulfonate groups in the membrane, only the Na+ from the buffer can pass through the membrane. The oxygen reacts with the water transported with Na+ and electrons to produce OH", which balances with the transported Na+ to keep electroneutrality at the cathode. </p> <p> Tris buffer without Na + was utilized as alternative anolyte in the biofuel cell. It was found that the cell with Tris buffer had a poorer performance in comparison with sodium phosphate buffer due to the increases of the anode and cathode overpotentials. Tris buffer does not constitute a solution to the problem. </p> <p> This work represents a step toward a more complete understanding of the properties of biofuel cells. To improve biofuel cell output, the herein identified H+ transport limitation in Na + contained Nation needs to be overcome. </p> / Thesis / Master of Applied Science (MASc)

Marine structures must withstand the corrosive effects of salt water in a way that is low cost, reliable, and environmentally friendly. Aluminum satisfies these conditions, and would be a good choice for a sacrificial anode to protect steel structures if it did not passivate. However, various elements can be added to aluminum to prevent this passivation. Currently, Al-Ga alloys are used commercially as sacrificial anodes but their performance is not consistent. In this research, Thermo-Calc software was used to simulate various aspects of the Al-Ga system in an attempt to understand and potentially correct this reliability issue. Simulations showed that gallium segregates to the grain boundaries during solidification and then diffuses back into the grains during cooling to room temperature. Simulations also suggest that faster cooling rates and larger grains cause the potential segregation of gallium at the grain boundaries to remain after cooling. A set of aluminum plus 0.1% weight percent gallium alloy plates were produced with varying cooling rates, along with a control set (cooled slowly in a sand mold). Some samples were later homogenized via annealing. Samples were subjected to a 168 hour long galvanostatic test to assess voltage response. The corrosion performance of samples was found to have both consistent and optimal voltage range when subjected to quick cooling rates followed by annealing. Testing samples at near freezing temperature seems to completely remove optimal corrosion behavior, suggesting that there are multiple causes for the voltage behavior. / Master of Science / Ships must withstand the corrosive effects of salt water in a way that is low cost, reliable, and environmentally friendly. Aluminum has properties which could allow a plate of it to rust instead of a ship it is attached to, thus protecting the ships from rusting. However, because aluminum usually does not rust, gallium can be added to aluminum to allow it to rust. Currently, aluminum-gallium alloys are used commercially to protect ships, but their performance is not consistent. In this research, various aspects of the aluminum-gallium system were simulated in an attempt to understand and potentially correct this reliability issue. Simulations showed that the gallium concentration may not be uniform in the alloy, and various conditions can cause the gallium concentration to be inconsistent. A set of aluminum-gallium alloy plates were cast in molds from liquid aluminum. Some of the plates were cooled quickly, and some cooled slowly. Some samples were later heated in an oven at high temperatures in an attempt to even out the gallium concentration. Samples were subjected to tests to observe corrosion behavior. The corrosion performance of samples was found to be best when subjected to quick cooling rates followed by the oven heating. Testing the samples in cold temperatures seemed to remove the desired corrosion behavior, suggesting that there are multiple reasons for the inconsistent corrosion behavior of aluminum gallium.