This thesis explores the possibility of alternatives to copper lining inside the water heater tank in water heaters. The need for an alternative is based on the increasing copper prices the recent years. The aim of this thesis is to compare three different materials, stainless steel, copper and a nickel coated plain carbon steel. This comparison is based on a basic corrosion test and a literature survey to render a merit value for each environment/metal interface. The testing solution consists of 100ppm Cl - concentration the specimens are tested in three different pH levels and at three different temperatures. The specimens have their weight measured before and after the test. The 15μm thick nickel coating was performed by Ferroprodukter AB, composing of 9% P and 91% Ni. The copper and stainless steel specimens are both from Thermia’s actual water heater tank. The copper lining is made of pure copper and the stainless steel hull is made of ferritic stainless steel. The results from the corrosion test are measured in weight change by modulus, |Δw|/w, for the comparison of the three materials. It was found that stainless steel was the worst material, performing better at higher temperatures and higher pH , but overall performance is far from copper and nickel’s corrosion properties. The nickel coating and copper specimen showed comparable results and perform more or less equally well. Regarding identification of corrosion mechanics, it may consist of either pitting and general corrosion damage or a mixture of both. To avoid the fact that weight change may be both negative and positive, the solution to this was to incorporate a merit value based on the absolute value of the weight change, divided by the initial weight of the specimen. In conclusion, stainless steel total weight change by modulus accumulates to 16.072g, nickel coated specimen accumulates a weight change by modulus equal to 8.544g, important note: two of the nickel coated specimen account for ~72.4% of the total weight change by modulus which then accumulates to 2.36g. Copper’s total weight change by modulus was 2.937g thus the lowest. However, disregarding from the 90캜 regime; stainless steel scores 13.496g, copper 2.151g, and nickel 1.095g.

<p> In this study, the performance of a Gold-Copper alloy has been examined in order to explore the possibility of its use as a cathode catalyst in a Proton Exchange Membrane (PEM) Fuel Cell. The performance of Oxygen Reduction Reaction (ORR), which occurs at the cathode, is evaluated using the Density Function Theory (DFT) computational code, SeqQuest. A surface segregation study is performed to identify a low energy surface of the catalyst. A binding site analysis of various intermediate molecules that occur during the ORR process is performed. The intermediate reactions of the ORR are simulated on the surface. Using the binding energies and energy barriers, the pathway that the Gold-Copper alloy prefers to follow is determined. The alloy is found to be a promising catalyst as it prefers to take the four electron pathway. An estimation of the Current Density has been made, and the effect the operating temperature has on it is observed.</p>

<p> In this work, beneficial effects of tensile mean strain on fatigue behavior and microstructure of superelastic NiTi (i.e. Nitinol) are studied. Most applications, such as endovascular stents made with NiTi, are subjected to a combination of constant and cyclic loading; thus, understanding the fatigue behavior of NiTi undergoing mean strain loading is necessary. Cyclic strain-controlled fatigue tests are designed to investigate the effects of tensile mean strain on fatigue of superelastic NiTi. Experimental observations show that combinations of large tensile mean strains and small strain amplitudes improve the fatigue life of superelastic NiTi. This behavior arises from reversible, stress-induced phase transformations. The phase transformations cause &ldquo;stress plateaus&rdquo; or strain ranges with no change in stress value. Scanning electron microscopy (SEM) of the fracture surfaces of specimens revealed generally short crack growth. Electron backscatter diffraction (EBSD) found the amount of residual martensite to be about ~8%, regardless of loading conditions.</p>

<p> Carbon-fiber composites are increasingly employed in the Aerospace and Automotive industries owing to their lightweight and excellent mechanical properties. However, this class of material, when subjected to out-of-plane loads, is often susceptible to an internal damage in the form of delamination that can severely reduce its load bearing capacity. Several toughening methods including the implementation of thermoplastic materials are used to increase the damage tolerance of the polymer-matrix composites. In particular, non-woven thermoplastic veils, when used as interleaving materials between the plies in a composite structure, is extremely efficient at improving the interlaminar (delamination) fracture toughness and impact-resistance of composites. In addition, the toughening of the polymer matrix, if not adversely affecting the manufacturing process, can result in an increase in the toughness-related properties of composite laminates such as the resistance to micro-cracking under thermal-cycling conditions. </p><p> In this study, the effects of matrix toughening and interleaving of the composite with non-woven Polyamide (PA) veils on the Interlaminar Fracture Toughness (ILFT) of Carbon-fiber/Benzoxazine composites are investigated. Formulated Benzoxazine (BZ) resins in non-toughened and toughened variants along with several non-woven PA veils with different melt temperatures are used to manufacture composite laminates through the Vacuum Assisted Resin Transfer Molding (VARTM) process. The ILFT of composites is measured by obtaining the resistance to crack propagation in the interlayer under tensile forces (Mode-I ILFT) or shear forces (Mode-II ILFT). The critical strain energy release rate (Gc) recorded during interlaminar fracture gives a measure of the ILFT of a composite. </p><p> The laminates interleaved with the PA veils show an increase of nearly 50% for the Mode-I crack initiation (GIc initiation), regardless of the melt temperature of the PA veils. The Mode-I crack propagation (GIc propagation) of the laminate increases by using the PA veils with melt temperatures lower than the cure temperature of the BZ resin. </p><p> In the Mode-II ILFT (GIIc) tests, the laminates interleaved with the PA veils show a significant impact on the GIIc values, as increases of nearly 170% are observed. A strong correlation between PA melt temperatures and the GIIc values is noted. The greatest GIIc values are noted when the melt temperature of the PA veil is greater than the cure temperature of the BZ resin. </p><p> The matrix toughness plays a significant role in affecting the GIc values. The laminates manufactured with the toughened BZ resin result in the greatest increase in the GIc values. In contrary, the use of the toughened BZ resin does not result in an improvement in the GIIc values.</p>

Since the development of batteries by Edison and Volta, energy storage has become an integral part of our technology. As the energy storage devices we manufacture, research and develop new energy storage systems has been standardized. This dissertation present three alternative approaches to developing energy storage devices which could completely change the paradigm by which we manufacture and use energy storage. First, I present my work in developing energy storage devices that can be directly integrated into the back of Silicon photovoltaics. This includes initial proof of concept of direct integration of porous Si supercapacitors followed by investigations into high rate faradaic chemical reactions with porous Si and coated porous Si. These faradaic reactions have the possibility of higher energy storage and power matching the performance of silicon photovoltaics. Second, I demonstrate the feasibility of using scrap metals to make high rate batteries that can be paired with photovoltaics by anodizing scrap steel and brass using simple manufacturing methods compatible with do it yourself manufacturing. Third, I will present my work in developing multifunctional structural supercapacitor composites. I demonstrate the ability to measure in-situ the electrochemical response of solid state electrolyte and supercapacitors. I follow this initial work up with the realization of a structural supercapacitor with the mechanical performance approaching that of commercial structural composites and energy storage performance approaching commercial supercapacitors.

<p> The next generation of rechargeable batteries must have significantly improved gravimetric and volumetric energy densities while maintaining a long cycle life and a low risk of catastrophic failure. Replacing the conventional graphite anode in a lithium ion battery with lithium foil increases the theoretical energy density of the battery by more than 40%. Furthermore, there is significant interest within the scientific community on new cathode chemistries, like sulfur and air, that presume the use of a lithium metal anode to achieve theoretical energy densities as high as 5217 W&dot;h/kg. However, lithium metal is highly unstable toward traditional liquid electrolytes like ethylene carbonate and dimethyl carbonate. The solid electrolyte interphase that forms between lithium metal and these liquid electrolytes is brittle which causes a highly irregular current distribution at the anode, resulting in the formation of lithium metal protrusions. Ionic current concentrates at these protrusions leading to the formation of lithium dendrites that propagate through the electrolyte as the battery is charged, causing it to fail by short-circuit. The rapid release of energy during this short-circuit event can result in catastrophic cell failure. </p><p> Polymer electrolytes are promising alternatives to traditional liquid electrolytes because they form a stable, elastomeric interface with lithium metal. Additionally, polymer electrolytes are significantly less flammable than their liquid electrolyte counterparts. The prototypical polymer electrolyte is poly(ethylene oxide). Unfortunately, when lithium anodes are used with a poly(ethylene oxide) electrolyte, lithium dendrites still form and cause premature battery failure. Theoretically, an electrolyte with a shear modulus twice that of lithium metal could eliminate the formation of lithium dendrites entirely. While a shear modulus of this magnitude is difficult to achieve with polymer electrolytes, we can greatly enhance the modulus of our electrolytes by covalently bonding the rubbery poly(ethylene oxide) to a glassy polystyrene chain. The block copolymer phase separates into a lamellar morphology yielding co-continuous nanoscale domains of poly(ethylene oxide), for ionic conduction, and polystyrene, for mechanical rigidity. On the macroscale, the electrolyte membrane is a tough free-standing film, while on the nanoscale, ions are transported through the liquid-like poly(ethylene oxide) domains. </p><p> Little is known about the formation of lithium dendrites from stiff polymer electrolyte membranes given the experimental challenges associated with imaging lithium metal. The objective of this dissertation is to strengthen our understanding of the influence of the electrolyte modulus on the formation and growth of lithium dendrites from lithium metal anodes. This understanding will help us design electrolytes that have the potential to more fully suppress the formation of dendrites yielding high energy density batteries that operate safely and have a long cycle life. </p><p> Synchrotron hard X-ray microtomography was used to non-destructively image the interior of lithium-polymer-lithium symmetric cells cycled to various stages of life. These experiments showed that in the early stages of lithium dendrite development, the bulk of the dendritic structure was inside of the lithium electrode. Furthermore, impurity particles were found at the base of the lithium dendrites. The portion of the lithium dendrite protruding into the electrolyte increased as the cell approached the end of life. This imaging technique allowed for the first glimpse at the portion of lithium dendrites that resides inside of the lithium electrode. </p><p> After finding a robust technique to study the formation and growth of lithium dendrites, a series of experiments were performed to elucidate the influence of the electrolyte&rsquo;s modulus on the formation of lithium dendrites. Typically, electrochemical cells using a polystyrene &ndash; block&not; &ndash; poly(ethylene oxide) copolymer electrolyte are operated at 90 &deg;C which is above the melting point of poly(ethylene oxide) and below the glass transition temperature of polystyrene. In these experiments, the formation of dendrites in cells operated at temperatures ranging from 90 &deg;C to 120 &deg;C were compared. The glass transition temperature of polystyrene (107 &deg;C) is included in this range resulting in a large change in electrolyte modulus over a relatively small temperature window. The X-ray microtomography experiments showed that as the polymer electrolyte shifted from a glassy state to a rubbery state, the portion of the lithium dendrite buried inside of the lithium metal electrode decreased. These images coupled with electrochemical characterization and rheological measurements shed light on the factors that influence dendrite growth through electrolytes with viscoelastic mechanical properties. (Abstract shortened by ProQuest.)</p>

<p> Carbon nanotubes (CNTs) are materials with significant potential applications due to their desirable mechanical and electronic properties, which can both vary based on their structure. Electronic applications for CNTs are still few and not widely available, mainly due to the difficulty in the control of fabrication. Carbon nanotubes are grown in batches, but despite many years of research from their first discovery in 1991, there are still many unanswered questions regarding how to control the structure of CNTs. This work attempts to bridge some of the gap between question and answer by focusing on the catalyst particle used in common CNT growth procedures. Ostwald ripening studies on iron nanoparticles are performed in an attempt to link catalyst morphology during growth and CNT chirality (the structure aspect of a nanotube that determines its electrical properties). These results suggest that inert gas dynamics play a critical role on the catalyst morphology during CNT growth. A novel method for CNT catalyst activation by substrate manipulation is presented. Results of this study build upon prior knowledge of the role of the chemistry of the substrate supporting CNT catalysts. By bombarding sapphire, a substrate known to not support CNT growth, with an argon ion beam, the substrate is transformed into an active CNT growth support by modifying both the structure and chemistry of the sapphire surface. Finally, catalyst formation is studied with transmission electron microscopy by depositing an iron gradient film in order to identify a potential critical catalyst size and morphology for CNT growth. A relationship between catalyst size and morphology has been identified that adds evidence to the hypothesis that a catalysts activity is determined by its size and ability to properly reduce.</p>

Nanomaterials have enabled significant breakthroughs in energy storage capabilities. In particular, the use of nanoscale components in lithium-sulfur and lithium-oxygen batteries have generated energy densities 2-3x greater than todayâs lithium-ion batteries. However, a major roadblock to commercially viable applications of nanomaterials is the ability to cost-effectively manufacture electrode-scale films while still maintaining precise control over the nanoscale morphology. In this regard, electrophoretic deposition (EPD) provides a promising tool for large-scale manufacture of nanomaterial systems using conventional liquid processing techniques. During EPD, the use of electrochemical equilibria to stabilize suspensions of nanomaterials eliminates the need for additives and provides a mechanism to control the placement of individual nanostructures on both 2D and 3D substrates through the application of an electric field. The viability of this process for large scale manufacture is demonstrated by integrating EPD electrode fabrication with nanomaterial synthesis processes on a benchtop roll-to-roll platform. Using this approach, lithium-sulfur and lithium-oxygen electrodes are fabricated that demonstrate enhanced mass-specific performance compared with identical material compositions assembled using conventional techniques. For lithium-oxygen batteries, the role that catalyst assembly plays in dictating the performance of the battery is elucidated and improved through EPD. Likewise, for lithium-sulfur batteries, the coating of an elemental sulfur layer is engineered in conjunction with an all-carbon EPD assembled electrode to produce one of highest capacity and most reversible lithium-sulfur cathodes ever reported. Overall, this thesis demonstrates the role of nanomaterial assembly in determining the energy storage performance of electrode-scale films and presents a method to control this assembly that is amenable to large-scale manufacture.

<p> Nanoparticles on a substrate have numerous applications in nanotechnology, from enhancements to solar cell efficiency to improvements in carbon nanotube growth. Producing nanoparticles in a cheap fashion with some control over size and spacing is difficult to do, but desired. This work presents a novel method for altering the radius and pitch distributions of nickel and gold nanoparticles in a scalable fashion. The introduction of alumina capping layers to thin nickel films during a pulsed laser-induced dewetting process has yielded reductions in the mean and standard deviation of radii and pitch for dewet nanoparticles. Carbon nanotube mats grown on these samples show a much thicker mat for the capped case. The same capping layers have produced an opposite effect of increased nanoparticle size and spacing during a solid state dewetting process of a gold film. These results also show a decrease in the magnitude of the effect as the capping layer thickness increases. Since the subject of research interest for using these nanoparticles has shifted towards producing ordered arrays with size and spacing control, the uncertainty in the values of these distributions needs to be quantified for any form of meaningful comparison to be made between fabrication methods. Presented here is a first step in the uncertainty analysis of such samples via synthetic images producing error distributions.</p>

Since the Nobel Prize awarded discovery that some polymers or “plastics” can be made electronically conducting, the scientific field of organic electronics has arisen. The use of conducting polymers in electronic devices is appealing, because the materials can be processed from a liquid phase, much like ordinary non-conducting plastics. This gives the opportunity to utilize printing technologies and manufacture electronics roll-to-roll on flexible substrates, ultimately at very low costs. Even more intriguing are the possibilities to achieve completely novel functionalities in combination with the inherent compatibility of these materials with biological species. Therefore, organic electronics can be merged with biology and medicine to create organic bioelectronics, i.e. organic electronic devices that interact with biological samples directly or are used for biological applications. This thesis aims at giving a background to the field of organic bioelectronics and focuses on how electrochemical devices may be utilized. An organic electronic wettability switch that can be used for lab-on-a-chip applications and control of cell growth as well as an electrochemical ion pump for cell communication and drug delivery are introduced. Furthermore, the underlying electrochemical structures that are the basis for the above mentioned devices, electrochemical display pixels etc. are discussed in detail. In summary, the work contributes to the understanding of electrochemical polymer electronics and, by presenting new bioelectronic inventions, builds a foundation for future projects and discoveries.