The objective of this creative project was to see if inspiration from historical and literal references could be integrated with an expressionistic approach to sculpture in the form of a memorial. This study involved creating a series of electroformed models or maquettes (seven final pieces) that examined this three-dimensional dilemma based on the concept of building a larger memorial sculpture for an abandoned cemetery near Oxford, Ohio, where my ancestors are buried (there are no monuments left in this wooded location). The cemetery, called the Freeman Cemetery, is named in honor of my Great Great Great Grandfather John Freeman, a Revolutionary War Soldier, who is buried there. This site was of particular concern as it is threatened to be disturbed and possibly built on as part of a nearby expanding housing development (it may not be protected by Ohio law). This study included looking at the site, the natural flora and fauna of the Midwest, the historical precedence in memorials, and the utilization of background in architecture to help generate the forms. It also involved learning the techniques of electroforming, sculptural construction and fabrication, and patina processes. / Department of Art

A novel process based on the principle of layered photolithography has been proposed and tested for making real three-dimensional micro-structures. An experimental setup was designed and built for doing experiments on this micro-fabrication process. An ultraviolet (UV) excimer laser at the wavelength of 248 nm was used as the light source and a single piece of photo-mask carrying a series of two dimensional (2D) patterns sliced from a three dimensional (3D) micro-part was employed for the photolithography process. The experiments were conducted on the solidification of liquid photopolymer from single layer to multiple layers. The single-layer photolithography experiments showed that certain photopolymers could be applied for the 3D micro-fabrication, and solid layers with sharp shapes could be formed from the liquid polymer identified. By using a unique alignment technique, multiple layers of photolithography was successfully realized for a micro-gear with features at 60 microns. Electroforming was also conducted for converting the photopolymer master to a metal cavity of the micro-gear, which proved that the process is feasible for micro-molding. / Singapore-MIT Alliance (SMA)

The H2/air micro PEMFC stacks were designed and fabricated in-house through MEMS (Micro-Electro-Mechanical System) technology with deep UV lithography manufacturing processes (SU-8 photoresist) and micro electroforming manufacturing processes to construct a novel metallic bipolar plate. The effect of different operating parameters on micro PEMFC stacks performance was experimentally investigated for serpentine flow-field configuration. Experiments were conducted through a serious laboratory experiments with different operating conditions of temperature (25oC, 35 oC and 50 oC), anode backpressures (97kPa, 153kPa, 207kPa) as well as anode humidifier temperature (25oC, 35 oC and 50 oC). Experimental results are presented in the form of polarization VI curves and PI curves under above operating conditions. The influence of the aforementioned parameters was presented and discussed.

Computer-aided design and simulation software are used in this thesis. AutoCAD is used to create pattern and mask; Pro/E is applied to build 3D model. TracePro software is used to simulate the optical performance. We use software for simulation and analysis. The data from simulation and analysis will be helpful to increase the strike-rate in process. Photolithography process is applied in this thesis for gapless crack polygonal lens array fabrication. In this process, photo resistance, AZ-4620 is spun on the substrate, and expose it after mask alignment, followed by the developing process. The cylinder column with the same size in diameter is formed after this process. Next, apply heat to photo resist. The cylinder structure becomes semi-sphere due to surface tension effect. Then, sputter silver layer on the semi-sphere. The semi-sphere becomes metal mold after nickel electroforming. Nickel alloy core is formed after electroplaing. Then, apply UV cuve resin on the nickel alloy core, and spinning out the extra UV glue. Then, cure it with UV light. Gapless crack polygonal lens array is completed after this series process. The result shows that it can be applied on different optical devices.

The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Title from PDF of title page (University of Missouri--Columbia, viewed on October 21, 2009). Thesis advisor: Dr. Hongbin Ma. Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (leaves 77-98).

Des couches minces co-deposées de Titanium Zirconium Vanadium (TiZrV) sont utilisés dans les accélérateurs de particules et les sources de lumière synchrotron pour maintenir les conditions d’ultravide. Elles sont pulvérisés sur les parois internes des chambres à vides, transformant celles-ci en « pompe chimique de gaz ». La tendance dans la conception d’accélérateurs d’électrons consiste à approcher les pôles des aimants de direction au plus près du faisceau d’électrons. Cela implique la réduction du diamètre des tubes hébergeant le vide et nécessite l’utilisation de très petits diamètres pour les chambres à vide. L’application du dépôt par vaporisation physique (PVD) dans un aussi faible diamètre devient alors très difficile. Le but de ce projet est de développer une nouvelle procédure de dépôt couplé à l’assemblage, en utilisant un mandrin sacrificiel en aluminium comme substrat de la couche mince en même temps que la création autour de lui de la chambre à vide elle-même par électroformage de cuivre. La première partie de l’étude concerne la production et la caractérisation de chambre de cuivre électroformées. La robustesse mécanique de l’assemblage complet a été validée, et les caractéristiques du film lui-même sont etudièes par microscopie électronique à balayage (MEB), diffraction des rayons X (DRX), spectrométrie de fluorescence-X (XRF) et spectrométrie de photoélectrons X (XPS). De plus, les performances de « pompage chimique des gaz » des nouvelles chambres à vide ainsi élaborées sont mesurées et comparées avec des valeurs de références de revêtements déposés par des procédures classiques dans des tubes de plus grand diamètres. La deuxième partie de l‘étude concerne l’évaluation des impuretés incluses lors des différentes étapes du procédé : le revêtement PVD, l’électroformage et l’étape de dissolution chimique du mandrin. La spectrométrie de désorption thermique et les profils de composition en épaisseur par XPS permettent de quantifier les impuretés dans le cuivre électroformé et dans le film de TiZrV. De plus, la présence d’hydrogène emprisonné dans le cuivre électroformé est étudiée à partir de différents bains à base de sulfate de cuivre. L’un d’entre eux, sans additifs, nécessite l’utilisation de courants pulsés. Le comportement électrochimique du bain permet la sélection de différents paramètres de séquences de pulses, dérivées de situations typiques des courbes transitoires. Finalement, le développement de prototypes de taille réelle a été atteint avec la création de chambres à vide revêtues de TiZrV de 2 mètres de long et 4mm de diamètre, ce qui n’a pas d’équivalent à ce jour. / Titanium Zirconium Vanadium (TiZrV) thin film coatings are used in particle accelerators and synchrotron light sources to maintain ultra-high vacuum conditions. They are deposited on the internal walls of the vacuum chambers, transforming them from a gas source into a chemical pump. The trend in electron accelerators design consists in approaching the poles of the steering magnets close to the electron beam. This implies reducing the bore hosting the vacuum chamber and using very small diameter vacuum pipes. The application of physical vapor deposition (PVD) in such small diameter chambers becomes then very difficult. The aim of this project is to develop a novel procedure of coating/assembly, using a sacrificial aluminium mandrel as substrate of the thin film together with the creation of a surrounding copper chamber by electroforming. The first part of the study deals with the production and characterization of the electroformed chambers. The mechanical robustness of the assembly is checked, and the film characterization is performed by secondary electron microscopy (SEM), X-ray diffraction analysis (XRD), X-ray Fluorescence Spectroscopy (XRF) and X-Ray Photoelectron Spectroscopy (XPS). Moreover, the pumping performance is measured and compared with reference values of coatings produced by the standard PVD technique. The second part of the study evaluates the impurities included during the different steps of the process: PVD coating, electroforming and chemical etching of the mandrel. Thermal desorption spectroscopy and XPS depth profiling allow to quantify the impurities in the electroformed copper and the TiZrV thin film. Furthermore, the presence of hydrogen trapped in the electroformed copper is studied for different copper sulphate baths. One of them, without additives, require the use of pulse currents. The electrochemical behaviour of the bath allows the selection of different pulse parameters, derived from typical situations on the transient curves. Finally, the development of real-scale prototypes was achieved with the creation of a 4 mm diameter, 2 meters TiZrV coated vacuum chamber, which is unrivalled up to date.

No description available.

The purpose of this research was to make an exploratory investigation of organic solutions containing the compounds aluminum bromide, aluminum stearate, basic aluminum acetate, aluminum phenoxide, aluminum o-nitrophenoxide, and aluminum acetylacetonate to determine if these compounds will furnish aluminum ions for electrodeposition. A review of the literature revealed that the ability of aluminum to resist corrosion by the atmosphere and many chemicals led to an extensive investigation of possible methods for electroplating aluminum on base metals. All of the studies on the electrodeposition of aluminum may be classified into four systems: aqueous solutions, nonaqueous organic liquid solutions, nonaqueous inorganic liquid solutions, and fused salts mixtures. Aluminum halides, especially aluminum chloride and bromide, probably have been the most frequently used solutes. One of the disadvantages of using a system containing aluminum halides is that these compounds pick up moisture readily from the atmosphere, and electrolysis results in the decomposition of the water with evolution of hydrogen at the cathode instead of electrodepositing aluminum. In the initial experiments, electrolyses were performed so that observations could be made of an aluminum deposit obtained from a nonaqueous liquid organic system and the conditions for electrodeposition. Current densities of 0.379 to 0.9 amperes per square decimeter were employed with a bath containing 5.067 grams of aluminum foil, and 110 and 70 millimeters of ethyl bromide and benzene, respectively. The aluminum anode replenished the bath with aluminum which was electrodeposited on a copper cathode. Four deposits were obtained in these electrolyses but they indicated that this bath has poor throwing power and it is extremely sensitive to a change in current density. The second series of experiments consisted of solubility tests with aluminum stearate in various organic solvents, and conductivity tests with the system aluminum stearate-ethyl phosphate-addition compounds. The addition of 0.4 gram of stearic acid and 0.8 gram of lithium stearate to a bath of 0.2 gram of aluminum stearate in 74.6 grams of ethyl phosphate resulted in the greatest increase in current obtained with any of the addition agents tested. Using platform electrodes one inch apart, the current increased from 0 to 5.3 milliamperes at 50 volts potential. These experiments were discontinued because of the low solubility of aluminum stearate in typical organic solvents and insufficient current for practical use. The third series of experiments consisted of solubility tests with basic aluminum acetate and electrolyses of the system basic aluminum acetate and formamide. Various types of organic solvents were tested but only formamide dissolved the basic aluminum acetate. Electrolysis of a bath containing 2.5 grams of basic aluminum acetate and 79.1 grams of formamide for 11.33 hours resulted in the formation of an unidentified precipitate in the bath and around the aluminum anode and copper cathode. This work was discontinued since gases were evolved and both electrodes and the current decreased from 100 to 35 milliamperes during electrolysis. In the fourth group of experiments, aluminum phenoxide, aluminum o-nitrophenoxide, sodium phenoxide, and sodium phenoxide, and sodium o-nitrophenoxide were prepared for use as mixed electrolytes. From the results of solubility tests with these compounds, the following systems were prepared and electrolyzed: 15 grams of aluminum o-nitrophenoxide, 1.5 grams of sodium o-nitrophenoxide, and 45 grams of methyl alcohol; 8 grams of aluminum phenoxide, 0.5 grams of sodium o-nitrophenoxide, and 106.1 grams of ethyl phosphate; 8 grams of aluminum phenoxide, 0.4 gram of sodium phenoxide, and 106.1 grams of ethyl phosphate. Using a combination of either a platinum anode and copper cathode or an aluminum anode and copper cathode, no aluminum was obtained in 1 to 6 hours of electrolysis at potentials of 8 to 50 volts. This work was discontinued because of evidence, in the form of heavy crust-like deposits on the electrodes, that the passage of current resulted in organic reactions. The final group of experiments consisted of the preparation of the acetylacetonates of aluminum and sodium for use as a mixed electrolyte, solubility tests in various types of organic solvents, and conductivity tests with several solutions. Conductivity tests at 10 to 30 volts potential across an aluminum anode and copper cathode, spaced one-half inch apart, showed no passage of current through three baths; each of the three solutions contained 0.2 to 0.3 gram of aluminum acetylacetonate in 9.2 grams of dimethyl glycol monobutyl ether, 7.9 grams of absolute alcohol, or 21.3 grams of ethyl phosphate, respectively. Since no current was observed in these tests, work with the acetylacetonates of aluminum and sodium was discontinued. / Master of Science

UV-LIGA is a microfabrication process realzed by material deposition through microfabricated molds. UV photolithography is conducted to pattern precise thick micro molds using UV light sensitive materials, mostly SU-8, and electroforming is performed to fabricate micro metallic structures defined by the micro molds. Therefore, UV-LIGA is a bottom-up in situ material-addition process. UV-LIGA has received broad attention recently than LIGA – a micro molding fabrication process using X-ray to pattern the micro molds. LIGA is an expansive and is limited in access. In comparing to LIGA, the UV-LIGA is a cost effective process, and is widely accessible and safe. Therefore, it has been extensively used for the fabrication of metallic micro-electro-mechanical-systems (MEMS). The motivation of this research was to study micro mechanical systems fabricated with nano-structured metallic materials via UV-LIGA process. Various micro mechanical systems with high-aspect-ratio and thick metallic structures have been developed and are presented in this desertation. A novel micro mechanical valve has been developed with nano-structured nickel realized with UV-LIGA fabrication technique. Robust compact valves are crucial for space applications where payload and rubstaness are critically concerned. Two types of large flow rate robust passive micro check valve arrays have been designed, fabricated and tested for robust hydraulic actuators. The first such micro valve developed employs nanostructured nickel as the valve flap and single-crystal silicon as the substrates to house inlet and outlet channels. The Nano-structured nickel valve flap was fabricated using the UV-LIGA process developed and the microchannels were fabricated by deep reactive etching (DRIE) method. The valves were designed to operate under a high pressure (>10MPa), able to operate at high frequencies (>10kHz) in cooperating with the PZT actuator to produce large flow rates (>10 cc/s). The fabricated microvalves weigh 0.2 gram, after packing with a novel designated valve stopper. The tested results showed that the micro valve was able to operate at up to 14kHz. This is a great difference in comparison to traditional mechanical valves whose operations are limited to 500 Hz or less. The advantages of micro machined valves attribute to the scaling laws. The second type of micro mechanical valves developed is a in situ assembled solid metallic (nickel) valves. Both the valve substrates for inlet and outlet channels and the valve flap, as well as the valve stopper were made by nickel through a UV-LIGA fabrication process developed. Continuous multiple micro molds fabrication and molding processes were performed. Final micro mechanical valves were received after removing the micro molds used to define the strutures. There is no any additional machining process, such as cutting or packaging. The alignment for laminated fabrication was realized under microscope, therefore it is a highly precise in situ fabrication process. Testing results show the valve has a forward flow rate of19 cc/s under a pressure difference of 90 psi. The backward flow rate of 0.023 cc/s, which is negligible (0.13%). Nano-structured nickel has also been used to develop laminated (sandwiched) micro cryogenic heater exchanger with the UV-LIGA process. Even though nickel is apparently not a good thermal conductor at room temperature, it is a good conductor at cryogentic temerpature since its thermal conductivity increases to 1250 W/k·m at 77K. Micro patterned SU-8 molds and electroformed nickel have been developed to realize the sandwiched heat exchanger. The SU-8 mold (200mm x 200mm x50mm) array was successfully removed after completing the nickel electroforming. The second layer of patterned SU-8 layer (200mm x 200mm x50mm, as a thermal insulating layer) was patterned and aligned on the top of the electroformed nickel structure to form the laminated (sandwiched) micro heat exchanger. The fabricated sandwiched structure can withstand cryogenic temperature (77K) without any damages (cracks or delaminations). A study on nanocomposite for micro mechanical systems using UV-LIGA compatible electroforming process has been performed. Single-walled carbon nanotubes (SWNTs) have been proven excellent mechanical properties and thermal conductive properties, such as high strength and elastic modulus, negative coefficient of thermal expansion (CTE) and a high thermal conductivity. These properties make SWNT an excellent reinforcement in nanocomposite for various applications. However, there has been a challenge of utilizing SWNTs for engineering applications due to difficulties in quality control and handling – too small (1-2nm in diameter). A novel copper/SWNT nanocomposite has been developed during this dissertational research. The goal of this research was to develop a heat spreader for high power electronics (HPE). Semiconductors for HPE, such as AlGaN/GaN high electron mobility transistors grown on SiC dies have a typical CTE about 4~6x10-6/k while most metallic heat spreaders such as copper have a CTE of more than 10x10-6/k. The SWNTs were successfully dispersed in the copper matrix to form the SWNT/Cu nano composite. The tested composite density is about 7.54 g/cm3, which indicating the SWNT volumetric fraction of 18%. SEM pictures show copper univformly coated on SWNT (worm-shaped structure). The measured CTE of the nanocomposite is 4.7 x 10-6/°C, perfectly matching that of SiC die (3.8 x 10-6/°C). The thermal conductivity derived by Wiedemann-Franz law after measuring composit's electrical conductivity, is 588 W/m-K, which is 40% better than that of pure copper. These properties are extremely important for the heat spreader/exchanger to remove the heat from HPE devices (SiC dies). Meanwhile, the matched CTE will reduce the resulted stress in the interface to prevent delaminations. Therefore, the naocomposite developed will be an excellent replacement material for the CuMo currently used in high power radar, and other HPE devices under developing. The mechanical performance and reliability of micro mechanical devices are critical for their application. In order to validate the design & simulation results, a direct (tensile) test method was developed to test the mechanical properties of the materials involved in this research, including nickel and SU-8. Micro machined specimens were fabricated and tested on a MTS Tytron Micro Force Tester with specially designed gripers. The tested fracture strength of nanostructured nickel is 900±70 MPa and of 50MPa for SU-8, resepctively which are much higher than published values.