In this study an experimental spray-rolling set-up is designed in order to produce rapidly solidified Al-Fe-V-Si flat product. Al-Fe-V-Si alloys produced by rapid solidification powder metallurgy (RSP/M) methods are mostly used in high temperature applications in aerospace and automotive industries. The RSP/M technique used is spray deposition, which is desirable because of the high cooling rates achieved, as a result fine silicide dispersoids and intermetallics are observed in the microstructure which are known to contribute to the mechanical properties i.e. high strength at elevated temperatures, thermal stability, fracture toughness, corrosion resistance. Since spray deposition is a droplet consolidation process a considerable amount of porosity is expected in the final product. In this work, spray rolling process, which consists of spray deposition and subsequent hot twin-rolling stage, is designed and developed by interpreting the results obtained from SEM, XRD, tensile, three point bending and hardness tests of the specimens formed in several design stages. Two original intermetallic phases characterized in this study are V3Si and V2Mg3Al18 .

Cu(In,Ga)(Se,S)2 (CIGS) solar cells have attracted a lot of attention due to their high performance and the prospect for lower manufacturing costs over conventional crystalline silicon solar cells. All recent record efficiency CIGS absorbers have been deposited using vacuum processing which introduces high manufacturing costs. CIGS can also be compatible with low cost, atmospheric processing which can significantly reduce manufacturing costs. Recently, there has been some progress in developing atmospheric solution-based processes for CIGS. Among different solution approaches, deposition of molecular precursors can be advantageous in terms of simplicity and straightforward compositional control. Nonetheless, the developed methodologies involve highly toxic reagents or large impurity content in the device, limiting the potential for commercialisation. This thesis describes the development of a novel solution-based approach for the deposition of CIGS absorber layers. Metal chalcogenides are used as the starting precursors, which are free from detrimental impurities. These compounds contain strong covalent bonds and, consequently, they are insoluble in common solvents. Until recently, hydrazine, which is highly toxic and explosive, was the only solvent to effectively dissolve these types of precursors, limiting the feasibility of this approach for industrial applications. In this work, metal chalcogenides are dissolved in a safer solvent combination of 1,2-ethanedithiol and 1,2-ethylenediamine, completely eliminating hydrazine from the process. By using this solvent system, optically transparent solutions are formed which exhibit long-term stability. The precursor solutions are decomposed cleanly and they are converted to single phase CIGS upon selenisation. CuIn(S,Se)2 solar cells with power conversion efficiencies up to 8.0% were successfully fabricated by spray depositing the precursor solution, followed by a selenisation step. This progress has been made by continuously optimising the deposition, drying, and especially the selenisation configuration. Among other parameters, the working pressure during selenisation was found to have a dramatic effect on the material crystalline quality. Rapid thermal processing was also explored as an alternative selenisation configuration to tube furnace annealing and it was shown to improve the back contact/absorber interface. It has been demonstrated that Ga can easily be incorporated in the absorber for band-gap tuning and, consequently, for VOC enhancement of the solar cells. The structural properties of the films were investigated with Ga content, as well as the opto-electronic characteristics of the corresponding solar cells. The band-gap of the material was conveniently varied by simply adjusting the precursor ratio, allowing for fine compositional control. By using this technique, Cu(In,Ga)(Se,S)2 solar cells with conversion efficiencies of up to 9.8% were obtained. The solar cell performance in this work is limited by the porosity of the absorber and the back contact quality. Despite a significant improvement during the course of this work, the remaining porosity of the absorber causes selenium to diffuse towards the back forming a thick MoSe2 layer and causing a high series resistance in the device. A low cost, solution-based technique was also developed for the deposition of aluminium-doped zinc oxide films that can be used as the transparent conductive oxide layer in thin film solar cells. This methodology involves the use of an ultrasonic spray pyrolysis system, which is a very versatile and easily controlled deposition technique. Although the presence of oxygen makes the film closer to stoichiometric (fewer oxygen vacancies) good electronic and optical properties have been obtained by process optimisation. Films deposited with optimum conditions exhibited a sheet resistance of 23 Ω/sq, which can be further reduced by increasing the thickness with minimal transmittance losses. The simplicity, low toxicity and straightforward control make the proposed methodologies extremely potential for low cost and scalable deposition of thin film solar cells.

Made available in DSpace on 2014-06-11T19:34:59Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-12-04Bitstream added on 2014-06-13T19:44:44Z : No. of bitstreams: 1 silva_rf_dr_botfca.pdf: 668304 bytes, checksum: 15daa12ad1f1aee63dd1cad95c4a3a4d (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Visando obter informações que possam contribuir para o melhor entendimento da eficácia de controle da lagarta do cartucho do milho, empregando defensivos agrícolas com diferentes mecanismos de ação, em diferentes doses, desenvolveu-se o presente trabalho procurando verificar o período de ação e o local de deposição na folha de milho, dos inseticidas lufenuron e lambdacialotrina, aplicados em pulverização com barra montada. Semeou-se uma área de 5.700 m2 com milho (Zea mays) do cultivar AL 25, na Fazenda Piloto do Departamento de Ciências Agrárias da Universidade de Taubaté. A pulverização dos defensivos agrícolas foi realizada aos 30 dias após a emergência das plantas, utilizando um trator com uma barra de pulverização de 12 m e pontas do tipo XR 8001 e XR 80015. O trator se deslocou a velocidade de 4 km/h numa parte da área e a 6 km/h na outra parte, de tal maneira que as subáreas receberam diferentes doses dos inseticidas, de acordo com a ponta utilizada e a velocidade de deslocamento do trator, obtendo-se 9 tratamentos. Após a pulverização dos inseticidas no campo, foi coletada a antepenúltima folha lançada de 10 plantas ao acaso em cada subárea, com 1, 5, 10 e 15 dias após a pulverização e levadas ao laboratório para a avaliação do número de lagartas sobreviventes. Ao chegar no laboratório, as folhas foram divididas em três regiões distintas: proximal, mediana e distal, em relação ao caule. Em seguida foi retirada a nervura central para evitar que se enrolassem. Partes das folhas foram colocadas em placas de “Petri” juntamente com 5 lagartas de 3º instar. As avaliações relativas à sobrevivência larval de S. frugiperda em todos os tratamentos, inclusive no tratamento testemunha, foram realizadas 24, 48, 72, 120 e 168 horas após a inoculação das lagartas. Cada época de coleta de folhas no campo foi considerada como um experimento... / Looking for better understanding the efficacy to control armyworm in maize crops using insecticides in different dosages and mode of action, this research aimed to verify the period of action and the correct area of deposition of the insecticides lambdacialothrin and lufenuron in spraying, through a set up bar. An area of 5,700 m2 was seeded with AL 25 maize (Zea mays) cultivar at the experimental farm from the Ciências Agrárias Department of Taubaté University. The insecticide sprayings were carried out 30 days after plants emergence, using a tractor coupled to a spraying with a bar of 12m length and tips XR 8001 and XR 80015. The tractor speed was 4.0 Km/h in the first half of the area and 6.0 Km/h in the second half and this way, both half areas received different insecticides dosages according to the speed established and the tip used, completing 9 treatments. In the field, 1, 5, 10 and 15 days after insecticide spraying, the leaf before the last of 10 plants were randomly collected from both areas and led to laboratory to evaluate the number of live armyworms. At the laboratory, the leaves were split up in 3 regions: the base region, middle region and top region in relation of maize stem. Afterward, the main vein was removed from each part to avoid dehydration. These little pieces of leaves were placed into a “Petri” dish with 5 larvae form 3rd instar. The surviving larvae of S. frugiperda in all treatments were determined 24, 48, 72, 120 and 168 hours after larvae inoculation. Each data from leaves collection in the field were considered a separate experiment. The obtained data were transformed in square root of (x + 0.5) and analyzed their variance... (Complete abstract click electronic access below)

La mise au point d'une cellule de SOFC haute performance de configuration anode support pour un fonctionnement sous méthane pur nécessite l'élaboration d'un film mince d'électrolyte et le développement d'une architecture innovante permettant le reformage d'hydrocarbures. La première partie du travail a consisté en l'élaboration de films minces d'électrolyte de zircone stabilisée à l'oxyde d'yttrium par atomisation électrostatique sur un substrat composite poreux NiO-8YSZ. Cette technique originale a permis l'obtention de films minces, denses et étanches à partir d'une suspension, présentant des propriétés électriques comparables à celles d'un échantillon massif de même composition. La seconde partie du travail a porté sur la mise au point d'une cellule de SOFC optimisée dont l'architecture innovante intégrant une membrane anodique catalytique est basée sur le concept associant le reformage interne progressif et le découplage électro-catalytique. Une séquence d'élaboration établie spécifiquement conditionne l'assemblage des éléments optimisés de la cellule. L'adaptation de la cellule dans un banc de mesures a permis la réalisation de tests électrochimiques sous hydrogène et méthane à haute température. Le fonctionnement stable du dispositif pendant plus de 1000 h sous méthane pur avec un taux d'utilisation optimisé, sans apport extérieur d'eau et sans dépôt de carbone a validé le concept étudié. / The design of a high performance anode supported SOFC operating under pure methane requires the elaboration of a thin film of electrolyte and the development of an original architecture adapted to the reforming of hydrocarbons. The first part of this work was dedicated to the elaboration of yttria stabilized zirconia thin films of electrolyte by ESD onto a NiO-8YSZ porous substrate. This original technique has allowed the fabrication of thin, dense and gas-tight films starting from a suspension, with good electrical properties comparable to that of a bulk sample of the same nature. The second part of this work concerned the design of an optimized SOFC cell with an original architecture integrating an anodic catalytic membrane based on a concept gathering the gradual internal reforming and the electro-catalytic dissociation. The assembly of the optimized components is conditioned by an elaboration sequence specifically established. The adjustment of the cell in a test bench led to the achievement of electrochemical tests in hydrogen and methane at 800°C. The stable operating of the cell fueled by pure and dry methane with optimized faradaic efficiency for more than 1000 h without carbon deposition proved the viability of the studied concept.

Reactive spray deposition technology (RSDT) is a method of depositing films or producing nanopowders through combustion of metal-organic compounds dissolved in a solvent. This technology produces powders of controllable size and quality by changing process parameters to control the stoichiometry of the final product. This results in a low-cost, continuous production method suitable for producing a wide range of fuel cell related catalyst films or powders. In this work, the system is modified for direct deposition of both unsupported and carbon supported layers on proton exchange membrane (PEM) fuel cells. The cell performance is investigated for platinum loadings of less than 0.15 mg/cm² using a heterogeneous bi-layer consisting of a layer of unsupported platinum followed by a composite layer of Nafion®, carbon and platinum. Comparison to more traditional composite cathode architectures is made at loadings of 0.12 and 0.05 mg platinum/cm². The composition and phase of the platinum catalyst is confirmed by XPS and XRD analysis while the particle size is analyzed by TEM microscopy. Cell voltages of 0.60 V at 1 A/cm² using H₂/O₂ at a loading of 0.053 mg platinum/cm² have been achieved. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate

Recent development in portable electronics and electric vehicles have increased the demand for high performance lithium ion batteries. However, it is still challenging to produce high energy and high power lithium ion batteries. The major objective of this research is to fabricate advanced electrode materials with enhanced power density and energy density. Porous Li4Ti5O12 (LTO) and its nanocomposites (with Si and reduced graphene oxide (rGO)) synthesized by electrostatic spray deposition (ESD) technique were mainly studied and promising electrochemical performance was achieved. In chapter 3, porous LTO thin film electrode was synthesized by ESD to solve the low energy density and low power density issues by providing good ionic and electronic conductivities. Electrochemical test results showed that it had a large specific capacity of 357 mAh g-1 at 0.15 A g-1, which was even higher than its theoretical capacity. It also exhibited very high rate capability of 98 mAh g-1 at 6 A g-1. The improved electrochemical performance was due to the advantage of ESD generated porous structures. In order to further enhance the power density of LTO, ESD derived LTO/rGO composite electrodes were studied in chapter 4. In chapter 5, high energy density component Si was introduced viii into LTO composite. The synergistic effect between commercial LTO and Si powder was studied. Then, ESD derived LTO/Si/rGO composite was prepared and evaluated. At 0.15 A g-1, a stable capacity of 624 mAh g-1 was observed, which was much higher than the capacities of LTO and LTO/rGO electrodes. In addition, effect of activation process on electrochemical performance of carbon nanofibers (ACNFs) and feasibility of ion intercalation into 2D MMT montmorillonite clay (MMT) were studied and discussed in chapter 6. In summary, we have successfully synthesized various LTO based electrodes by ESD. Both high energy and high power density were achieved as compared to commercial LTO electrode. Through electrochemical characterization and charge storage distribution analysis, origins of the high rate capability were proposed. This work demonstrates ESD as a powerful tool for fabricating high performance porous structures and nanocomposite electrode materials.

No description available.

<p>In this research, we have studied the interaction between femtosecond laser and dielectric material, especially borosilicate glass, and its applications. Using laser direct writing (LDW), optical fiber sensors and selective metallization of glass surface were explored. For ultrafine selective metallization, supersonic spray deposition system was introduced combining to femtosecond laser direct writing.</p>

Ba(Zr0.1Ce0.7Y0.2)O3-£_ (BZCY) shows high proton conductivity as well as high chemical stability over a wide range of solid oxide fuel cell (SOFC) operating conditions. Sm0.5Sr0.5CoO3-£_ (SSC) cathode deposited by electrostatic spray deposition (ESD) on SOFC half cell obtained via tape-casting shows porous and reticular microstructure, and the SOFC single cell consists of substrate/ BZCY+NiO/ BZCY/ SSC. The electrolyte thickness decrease from 22 £gm, 20 £gm, 17.6 £gm to 15.1 £gm after sintering as the content of carbon pore former in the corresponding anode functional layer increased from 0.0 wt.%, 5.0 wt.%, 10.0 wt.% to 15.0 wt.%, and the maximum power density of corresponding cells at 700¢J varies from 476.89 mW/cm2, 713.34 mW/cm2, 862.50 mW/cm2 to 706.89 mW/cm2, respectively.

Orientador: Wilson Badiali Crocomo / Banca: Carlos Gilberto Raetano / Banca: Silvia Renata Siciliano Wilcken / Banca: Ronaldo Pavarini / Banca: Adriana Mascarette Labinas / Resumo: Visando obter informações que possam contribuir para o melhor entendimento da eficácia de controle da lagarta do cartucho do milho, empregando defensivos agrícolas com diferentes mecanismos de ação, em diferentes doses, desenvolveu-se o presente trabalho procurando verificar o período de ação e o local de deposição na folha de milho, dos inseticidas lufenuron e lambdacialotrina, aplicados em pulverização com barra montada. Semeou-se uma área de 5.700 m2 com milho (Zea mays) do cultivar AL 25, na Fazenda Piloto do Departamento de Ciências Agrárias da Universidade de Taubaté. A pulverização dos defensivos agrícolas foi realizada aos 30 dias após a emergência das plantas, utilizando um trator com uma barra de pulverização de 12 m e pontas do tipo XR 8001 e XR 80015. O trator se deslocou a velocidade de 4 km/h numa parte da área e a 6 km/h na outra parte, de tal maneira que as subáreas receberam diferentes doses dos inseticidas, de acordo com a ponta utilizada e a velocidade de deslocamento do trator, obtendo-se 9 tratamentos. Após a pulverização dos inseticidas no campo, foi coletada a antepenúltima folha lançada de 10 plantas ao acaso em cada subárea, com 1, 5, 10 e 15 dias após a pulverização e levadas ao laboratório para a avaliação do número de lagartas sobreviventes. Ao chegar no laboratório, as folhas foram divididas em três regiões distintas: proximal, mediana e distal, em relação ao caule. Em seguida foi retirada a nervura central para evitar que se enrolassem. Partes das folhas foram colocadas em placas de "Petri" juntamente com 5 lagartas de 3º instar. As avaliações relativas à sobrevivência larval de S. frugiperda em todos os tratamentos, inclusive no tratamento testemunha, foram realizadas 24, 48, 72, 120 e 168 horas após a inoculação das lagartas. Cada época de coleta de folhas no campo foi considerada como um experimento... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Looking for better understanding the efficacy to control armyworm in maize crops using insecticides in different dosages and mode of action, this research aimed to verify the period of action and the correct area of deposition of the insecticides lambdacialothrin and lufenuron in spraying, through a set up bar. An area of 5,700 m2 was seeded with AL 25 maize (Zea mays) cultivar at the experimental farm from the Ciências Agrárias Department of Taubaté University. The insecticide sprayings were carried out 30 days after plants emergence, using a tractor coupled to a spraying with a bar of 12m length and tips XR 8001 and XR 80015. The tractor speed was 4.0 Km/h in the first half of the area and 6.0 Km/h in the second half and this way, both half areas received different insecticides dosages according to the speed established and the tip used, completing 9 treatments. In the field, 1, 5, 10 and 15 days after insecticide spraying, the leaf before the last of 10 plants were randomly collected from both areas and led to laboratory to evaluate the number of live armyworms. At the laboratory, the leaves were split up in 3 regions: the base region, middle region and top region in relation of maize stem. Afterward, the main vein was removed from each part to avoid dehydration. These little pieces of leaves were placed into a "Petri" dish with 5 larvae form 3rd instar. The surviving larvae of S. frugiperda in all treatments were determined 24, 48, 72, 120 and 168 hours after larvae inoculation. Each data from leaves collection in the field were considered a separate experiment. The obtained data were transformed in square root of (x + 0.5) and analyzed their variance... (Complete abstract click electronic access below) / Doutor