Processing and Characterisation of Tubular Solid Oxide Fuel Cell (SOFC) Cathodes using a Novel Manufacturing Technique

This thesis investigates a novel method for manufacturing a tubular solid oxide fuel cell cathode. The work involved depositing a lanthanum nickel ferrite / lanthanum strontium manganite cathode onto an yttria stabilized zirconia electrolyte using an electroless co-deposition technique. The lanthanum nickel ferrite is a promising cathode material but suffers from degradation at the high temperatures encountered during the sintering process which is required during conventional cathode processing.The novel technique employed in this work does not involve these high temperatures so the investigation was focused on whether co-deposition could be employed to use the lanthanum nickel ferrite (LNF). The experimental work involved co-deposition of conventional cathode materials – lanthanum strontium manganite and yttria stabilized zirconia onto both planar and tubular sections of alumina substrates, under the environment of both acid and alkaline baths. This was followed by repeating the procedure using lanthanum nickel ferrite onto tubular and planar yttria stabilized zirconia substrates.The performance of these co-deposited cathodes was characterized using optical and scanning electron microscopy, energy dispersive X-ray analysis and electrochemical analysis. These were planar fuel cells so as to allow basic testing of the cells. The work thus demonstrated that electroless co-deposition of tubular cathodes incorporating LNF was successful – both via SEM / EDX characterisation and basic electrical testing.Factors which affected the coating deposition and performance were also investigated and a comprehensive overview of the development of solid oxide fuel cells is also detailed

Electroplating of Nanostructures

The electroplating was widely used to electrodeposit the nanostructures because of its relatively low deposition temperature, low cost and controlling the thickness of the coatings. With advances in electronics and microprocessor, the amount and form of the electrodeposition current applied can be controlled. The pulse electrodeposition has the interesting advantages such as higher current density application, higher efficiency and more variable parameters compared to direct current density. This book collects new developments about electroplating and its use in nanotechnology

Fabrication and characterisation of planar and tubular solid oxide fuel cell anodes

Solid Oxide Fuel Cells (SOFCs) are energy conversion devices that convert the chemical energy of a fuel directly into electricity and useful heat, where the latter is recovered at the device’s high working temperature. SOFCs have become important in the fuel cell field due to their high energy conversion efficiency, wide range of fuels and environmental friendliness. However, one of the main obstacles to put SOFCs into mass production is their high fabrication costs including the cost of components such as the electrodes – anodes and cathodes. This project investigates the possibility of manufacturing anodes for tubular SOFCs by a novel co-deposition process which can reduce costs compared with conventional fabrication techniques. Anode requires a ceramic phase to help match the coefficient of thermal expansion of the electrolyte and a metallic phase to conduct electrons to the outside circuit. Both of these can be achieved via a novel nickel-ceramic electroless co-deposition technique. Both ceramic and metallic parts of the anode are deposited together in one single process and avoid the expensive sintering process which is involved in traditional techniques. The elimination of multi-stage processing and high thermal consumption reduces the time and cost of the anode fabrication process. The main challenge in this project is to increase the content of ceramic particles embedded in the nickel. The variables investigated are (i) ceramic particle size, (ii) plating time and (iii) the plating performance both on the inside and outside of tubular surfaces. Initial experiments were carried out on planar surface

Conductive textiles for signal sensing and technical applications

Conductive textiles have found notable applications as electrodes and sensors capable of detecting biosignals like the electrocardiogram (ECG), electrogastrogram (EGG), electroencephalogram (EEG), and electromyogram (EMG), etc; other applications include electromagnetic shielding, supercapacitors, and soft robotics. There are several classes of materials that impart conductivity, including polymers, metals, and non-metals. The most significant materials are Polypyrrole (PPy), Polyaniline (PANI), Poly(3,4-ethylenedioxythiophene) (PEDOT), carbon, and metallic nanoparticles. The processes of making conductive textiles include various deposition methods, polymerization, coating, and printing. The parameters, such as conductivity and electromagnetic shielding, are prerequisites that set the benchmark for the performance of conductive textile materials. This review paper focuses on the raw materials that are used for conductive textiles, various approaches that impart conductivity, the fabrication of conductive materials, testing methods of electrical parameters, and key technical applications, challenges, and future potential

Conception et développement d'un procédé d'électrodéposition d'alliages biodégradables à base de fer pour stents cardiovasculaires

Les maladies cardiovasculaires (MCV) sont les principales responsables de décès dans le monde. L'athérosclérose est la forme la plus répandue de MCV, causée en partie et dans les cas extrêmes par l'occlusion des vaisseaux en raison du vieillissement ou des facteurs de risque. L’implantation d’un stent vasculaire est le traitement le plus efficace pour les traitements des artères sténosées, en fournissant un support mécanique pour rétablir la circulation sanguine. En considérant une période approximative d'un an pour la guérison des artères, les Métaux Biodégradables (MB) ont été proposés et développées pour la fabrication de stents. Ils sont censés se dissoudre complètement après un certain délai, offre un support mécanique temporaire, empêcher des complications à long terme. Présentant des propriétés mécaniques supérieures par rapport aux alliages à base de Mg et à base de Zn, les MB à base de Fe, en particulier les alliages binaires de Fe-Mn, sont parmi les candidats les plus appropriés pour la fabrication des stents cardiovasculaires. La fabrication des stents est un procédé multi-étape qui inclut l’extrusion, le coupe laser, des traitements thermiques, et des procédés de neutralisation, et un fini de surface. L'électrodéposition s'est déjà révélé être une méthode efficace pour la micro-fabrication telle que le stent en fer pur. Par conséquent, ce travail porte sur la conception et le développement d'un procédé d'électrodéposition pour la production d'alliages biodégradables binaires de Fe-Mn pour l'application de stents vasculaires. Dans ce projet, deux approches ont été étudiées. Dans la première, l'alliage binaire de Fe-Mn a été fabriqué par un processus d'interdiffusion entre des couches précédemment déposées de fer pur et de manganèse pur. Dans la deuxième, le co-dépôt d'alliage de Fe-Mn était visé par un dépôt simultané à partir du même électrolyte. Les deux approches aboutissent à un alliage binaire de fer et de manganèse, mais elles présentent certaines limites. Dans le premier, une couche de diffusion de quelques micromètres d'épaisseur s'est formée à leur interface, mais les surfaces extérieures ont été partiellement oxydées. Dans ce dernier, le manganèse a été déposé jusqu'à 7% en poids, mais la couche déposée souffre de faibles propriétés physiques.Cardiovascular diseases (CVDs) are the leading reason for mortality in the world. Atherosclerosis is the most widespread form of CVD, partly caused in extreme cases by vessel occlusion because of aging or risk factors.Stenting is the most effective treatment for late atherosclerosis by providing mechanical support to re-open the arteries. It takes approximately one-year period for artery healing, so biodegradable metals (BMs) have been considered for stent manufacturing. They are supposed to dissolve completely after a specific time while providing temporary mechanical support, with imposing lower long-term complications. Showing superior mechanical properties compared to Mg-based and Zn-based alloys, Fe-based BMs, particularly binary Fe-Mn, are among the most suitable candidates for cardiovascular stents. The stent fabrication is a multi-step process that involves many steps, namely, extrusion, laser cutting, thermal treatment,neutralization processes, surface finishing. Electrodeposition has shown to be an efficient method for microfabrication, such as the pure iron stent.Therefore, this work deals with the development of an electrodeposition process for the production of binary Fe-Mn biodegradable alloys for vascular stent application. In this project, two different approaches for the development of the binary Fe-Mn alloy are explored. In the first, binary Fe-Mn alloy was approached through the interdiffusion process between the previously deposited layers of pure iron and pure manganese. In the second, however, the co-deposition of Fe-Mn alloy was aimed through simultaneous deposition from the same electrolyte. Both approaches result in binary iron and manganese alloy, but they showed some limitations. In the former, a diffusion layer of some micrometers thickness was formed at their interface, but exterior surfaces were partially oxidized. In the latter, manganese was co-deposited up to 7 wt. %, but the deposited layer suffers from low physical properties

Heat treatment, microstructure and properties of 75Cr1 steel, for use in heavy loaded elements

This study aims to optimize the heat treatment of tool steel 75Cr1 which is used for heavy loaded elements in transmissions. A salt bath was used to quench and temper the steel at different temperatures. Mechanical tests and microstructural characterization were done to define the heat treatment parameters corresponding to the optimal performance of the elements. Optical microscopy, electron back scatter diffraction and x-ray diffraction were used to characterize the microstructure, while tensile tests and toughness tests were employed to determine the mechanical properties after different heat treatments. It was found that the yield strength decreases with increasing annealing temperature and that the toughness decreases with increasing annealing time and temperature. The changes of the mechanical properties are discussed in relation with the thermal treatment and the corresponding microstructures

Tribological Comparison of Traditional and Advanced Firearm Coatings

The objective of this project is to find which type of coating has the best performance characteristics for finishing firearms. This is accomplished by measuring and comparing several performance characteristics, such as: adhesion, hardness, wear resistance, friction control, and corrosion resistance. Appearance is not a factor since any exterior coating that is flashy can be subdued or camouflaged with special purpose paints, which have proven durable enough for such purposes. Cost will not be a limiting factor for this experiment, but will be discussed in the conclusion as a secondary concern. This data will be used to identify the best coating for steel and aluminum firearm parts. The goal is to lengthen a firearm’s life cycle while increasing performance and reliability by applying the best coating

FERROELECTRIC PVDF-BASED POLYMER THIN FILMS AND NANOSTRUCTURES

Ph.DDOCTOR OF PHILOSOPH