La projection plasma sous très basse pression (communément désignée par son acronymeanglais VLPPS : « Very Low Pressure Plasma Spraying ») est un procédé émergent de traitement desurface par voie sèche permettant l’élaboration de dépôts métalliques et céramiques (type oxydes),sous des conditions de pression réduite, de l'ordre d'une centaine de Pascal, par utilisation d'un jet deplasma thermique. Un tel niveau de pression permet principalement la formation de dépôts parcondensation de vapeurs résultant de la vaporisation, partielle ou totale, des précurseurshabituellement sous forme solide. C'est principalement en cela que ce procédé diffère des procédésplus conventionnels de projection thermique, conduisant à la formation de dépôts par l'écrasement, lasolidification et l'empilement de particules liquides fondues dans un jet de forte énergie. En fonctiondes conditions de projection employées, les revêtements élaborés par VLPPS peuvent présenterdifférents types de microstructure, de colonnaires à lamellaires, de très denses à poreuses. Le modemixte de construction, caractérisé par la présence de vapeurs condensées et particules fonduesresolidifées peut également être rencontré.L'objectif global de ce travail est d'explorer le potentiel du procédé VLPPS en mode réactif envue de former des dépôts de matériaux présentant une fusion non congruente. Pour ce faire,l'aluminium et le titane ont été considérés comme matériaux métalliques précurseurs et l'azote commeélément réactif. Les matériaux qui pourraient résulter seraient alors des nitrures d'aluminium et detitane. Ces matériaux ont été sélectionnés avant tout comme matériaux démonstrateurs. Desapplications potentielles pourraient cependant rapidement déboucher en cas de performancessatisfaisantes : l'élaboration, sur de grandes surfaces, de couches de nitrures de titane et d'aluminium,présentant de bonnes résistances à l'oxydation ainsi que de bonnes propriétés tribologiques,notamment une résistance élevée à l'usure.Au cours de cette étude, des dépôts métalliques d’aluminium, titane et titane-aluminium et desdépôts composites nitrurés Al-AlN, Ti-TiN et TiAl-TiAlN ont été élaborés par projection VLPPS enmode réactif. Les dépôts composites nitrurés présentent par exemple des duretés moyennes plusimportantes que celles des dépôts métalliques. Ces dépôts renferment jusqu'à 30%at. d'azote et lescomposés TixN, AlN et TixAlN ont été clairement identifiés. / The Very Low Pressure Plasma Spraying (VLPPS) is an emerging deposition process tomanufacture metallic and ceramic coatings, under a very low surrounding pressure, typically about onehundred Pascal, thanks to a thermal plasma jet. Such a pressure range allows principallymanufacturing coatings by condensation of vapors resulting from the vaporization, partial or total, ofsolid precursors, in most of the cases. This is the main difference of this process compared to moreconventional thermal spray processes, which form coatings by spreading, solidification and stacking ofparticles melted in a high energy jet. Depending upon the spray operating conditions, coatingsmanufactured by VLPPS exhibit different types of microstructures, from columnar to lamellar, fromdense to porous. The coating building dual mode, made of condensed vapors and molten particles isalso possible.The aim of this work is to explore in a reactive mode the VLPPS potential to manufacturecoatings made of materials exhibiting a non-congruent melting behavior. Here, for a demonstrationpurpose, Aluminum and Titanium were considered as the metallic precursors and Nitrogen as thereactive element. Therefore, materials which could result would be Aluminum and Titanium nitrides.Some possible applications could result directly from this study: the manufacturing on large surfacesof Aluminum and Titanium nitride layers, exhibiting good oxidation resistance and tribologicalproperties, especially a high wear resistance.In this study, metallic coatings of Aluminum, Titanium and Aluminum-Titanium and Al-AlN,Ti-TiN and TiAl-TiAlN coatings were manufactured by reactive VLPPS. Nitrided composite coatingsexhibit, for example, higher average hardness than metallic coatings, Those coatings embed up to 30at.% of Nitrogen and TixN, AlN and TixAlN compounds were clearly identified.

Ceria (CeO2), chromia (Cr2O3), yttria-stabilized zirconia (Y2O3-ZrO2), and sodium cerium oxide (Na2CeO3) were used as barrier coatings on Ufala, an alumina-based ceramic refractory, to determine if they were effective at increasing the life of the refractory in a high-temperature black liquor gasification environment. The ceria, chromia, and yttria-stabilized zirconia coatings were applied at atmospheric pressure using a coating applicator at the Institute of Paper Science and Technology at the Georgia Institute of Technology. The sodium cerium oxide coatings in addition to the three other coating types were applied under atmospheric pressure at C3 International Technologies in Alpharetta, GA. The coated refractory, as well as a set of uncoated refractory used for baseline analysis, were tested using molten synthetic smelt at 1000C for 36 hours. Uncoated refractory samples were also tested for 12, 72, 120, and 168 hours in order to make a kinetic reaction rate determination. The refractory were analyzed using gravimetric and dimensional analysis, X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray spectroscopy to determine the severity of the physical changes that occurred after exposure to molten smelt. The data gathered from these experiments were not able to conclude that barrier coatings are sufficient to impede corrosion of the Ufala refractory material in molten smelt.

The effects of edible chitosan coating on quality factors of pomegranate (Punica granatum) arils were investigated in the present research. For that purpose, pomegranate arils were treated with 0% (control) and 1% chitosan (extracted from shrimp shells and deacetylated (.75%)) solutions and stored at 4

Thermal energy storage (TES) is one of the most attractive and cost effective solutions to the intermittent generation systems like solar, wind and other renewable sources, compared to alternatives. It creates a bridge between the power supply and demand during peak hours or at times of emergency to ensure the continuous supply of energy. Among all the TES systems, latent heat thermal energy storage (LHTES) draws lots of interests as it has high energy density and can store or retrieve energy isothermally. Two major technical challenges associated with the LHTES are low thermal conductivity of the phase change materials (PCMs), and corrosion tendency of the containment vessel with the PCMs. Macro-encapsulation of the PCM is one of the techniques to encounter the low thermal conductivity issue as it will maximize the heat transfer area for the given volume of the PCM and restrict the PCMs to get in contact with the containment vessel. However, finding a suitable encapsulation technique that can address the volumetric expansion problem and compatible shell material are significant barriers of this approach. In the present work, an innovative technique to encapsulate PCMs that melt in the 100-350 oC temperature range was developed for industrial and private applications. This technique did not require a sacrificial layer to accommodate the volumetric expansion of the PCMs on melting. The encapsulation consisted of coating a non-reactive polymer over the PCM pellet followed by deposition of a metal layer by a novel non-vacuum metal deposition technique. The fabricated spherical capsules were tested in different heat transfer fluid (HTF) environments like air, oil and molten salt (solar salt). Thermophysical properties of the PCMs were investigated by DSC/TGA, IR and weight change analysis before and after the thermal cycling. Also, the constrained melting and solidification of sodium nitrate PCM inside the spherical capsules of different sizes were compared to explore the charging and discharging time. To accomplish this, three thermocouples were installed vertically inside the capsule at three equidistant positions. Low-density graphene was dispersed in the PCM to increase its conductivity and compared with pure PCM capsules. A laboratory scale packed-bed LHTES system was designed and built to investigate the performance of the capsules. Sodium nitrate (m.p. 306oC) was used as the PCM and air was used as the heat transfer fluid (HTF). The storage system was operated between 286oC and 326oC and the volumetric flow rate of the HTF was varied from 110 m3/h to 151 m3/h. The temperature distribution along the bed (radially and axially) and inside the capsules was monitored continuously during charging and discharging of the system. The effect of the HTF mass flow rate on the charging and discharging time and on the pressure drop across the bed was evaluated. Also, the energy and exergy efficiencies were calculated for three different flow rates. Finally, a step-by-step trial manufacturing process was proposed to produce large number of spherical capsules.

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In order to obtain sustainable engineering systems, this research investigates surface and interface properties of metals and active nanostructured coatings. The goal is to develop new approaches in order to improve the corrosion resistance and obtain knowledge in reconstruction of worn and/or corroded surfaces. The research will focus on high carbon steels as the substrate. These materials are used in most of industries and vehicles like aircrafts and automobiles. For anti-corrosion and self-healing applications, the layer-by-layered (LBL) coatings consisting photo-catalytic materials, the corrosion inhibitor, and the polyelectrolyte will be studied. Potential dynamic tests will be carried out in order to characterize the corrosion potential and current. For wear study, we will develop a metallic composite that has several functions, such as corrosion and wear protection, refresh or reverse worn or corroded surface. Characterization techniques used include optical microscope, surface interferometer, tribometer and the hardness tester. The ultimate goal of this research is to understand several types of problems on metal surface, such as corrosion and wear, and explore the possible ways to reduce those by using active nano-structured composite coating on metal surface.

No description available.

Submitted by marcelo capella de campos (kapellla@yahoo.com.br) on 2018-03-16T15:03:39Z No. of bitstreams: 1 Campos_MC - tese corrigida.pdf: 3583190 bytes, checksum: 1db0dbc48ebc01935b750b73717116dc (MD5) / Approved for entry into archive by Maria Marlene Zaniboni null (zaniboni@bauru.unesp.br) on 2018-03-16T19:03:37Z (GMT) No. of bitstreams: 1 campos_mc_dr_bauru.pdf: 3583190 bytes, checksum: 1db0dbc48ebc01935b750b73717116dc (MD5) / Made available in DSpace on 2018-03-16T19:03:37Z (GMT). No. of bitstreams: 1 campos_mc_dr_bauru.pdf: 3583190 bytes, checksum: 1db0dbc48ebc01935b750b73717116dc (MD5) Previous issue date: 2018-01-26 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Os laminados de compósitos poliméricos possuem um valor já consagrado dentro das aplicações mecânicas e industriais. Sua versatilidade aliada a suas propriedades mecânicas, incentivam o aumento das aplicações, devido em partes pela facilidade de construção, tornando-os competitivos com relação a outros materiais. O conhecimento sobre a matriz polimérica, que possui inúmeras variações e aplicações, neste trabalho contou com o estudo de três tipos, sendo duas do grupo bisfenol “a” e uma do grupo bisfenol “f”. A caracterização destas matrizes através das técnicas de TG e DSC, influenciaram na escolha em virtude da aplicação a qual seriam submetidas. E sobre o reforço, que neste estudo, utilizou tecidos de fibra de carbono em trama de tela. O processo de fabricação dos laminados através de infusão a vácuo contribuiu para um resultado satisfatório, demonstrando vantagens com relação à melhor impregnação e minimizando os possíveis vazios na matriz. Os dois tipos de revestimento aplicados nestes laminados, sendo um chamado de revestimento a frio, que é um produto composto por três tipos de materiais distintos, metal, cerâmica e polímeros e o segundo a aspersão térmica, através da técnica de aspersão por chama de arames, contendo carbeto de tungstênio, recobriram o material de forma eficiente, mantendo boa adesão superficial. Estes laminados recobertos tem a finalidade de terem a vida útil aumentada e proporcionar uma maior resistência a abrasão severa. Os ensaios mecânicos aplicados demonstram as boas características destes materiais, juntamente com a caracterização por microscopia óptica e microscopia eletrônica de varredura, revelaram a boa adesão entre laminados e revestimentos, concluindo que existe uma boa identidade para estes materiais, sendo uma das principais conclusões. / The laminates of polymeric composites have an already established value within the mechanical and industrial applications. Its versatility combined with its mechanical properties, encourage the increase the applications, due in part for the ease of construction, making them competitive with respect to other materials. The knowledge about the polymer matrix, which has numerous variations and applications, in this work had the study of three types, two of the bisphenol group "a" and one of the bisphenol "f" group. The characterization of these matrices through TG and DSC techniques influenced the choice by virtue of the application to which they would be submitted. And on the reinforcement, which in this study, used carbon fiber fabrics in screen fabric. The process of manufacturing the laminates through vacuum infusion contributed to a satisfactory result, demonstrating advantages in relation to the better impregnation and minimizing voids in the matrix. The two types of coating applied on these laminates, one called cold coating, which is a product composed of three different types of materials, metal, ceramic and polymers and the second the thermal spray, by the flame spray technique of wires , Containing tungsten carbide, coated the material efficiently, maintaining good surface adhesion. These coated laminates have the purpose of having increased shelf life and providing greater resistance to severe abrasions. The applied mechanical tests demonstrate the good characteristics of these materials, together with the characterization by optical microscopy and scanning electron microscopy, revealed the good adhesion between laminates and coatings, concluding that there is a good identity for these materials.

Submitted by ANDERSON FIGUEIREDO DA COSTA null (and.kairos@hotmail.com) on 2016-11-06T23:21:09Z No. of bitstreams: 1 Dissertação 20161104.pdf: 2526366 bytes, checksum: 11d77bc71653027d529eb9107a2d4a53 (MD5) / Rejected by LUIZA DE MENEZES ROMANETTO null (luizaromanetto@hotmail.com), reason: Solicitamos que realize uma nova submissão seguindo a orientação abaixo: O arquivo submetido está sem a ficha catalográfica. A versão submetida por você é considerada a versão final da dissertação/tese, portanto não poderá ocorrer qualquer alteração em seu conteúdo após a aprovação. Corrija esta informação e realize uma nova submissão com o arquivo correto. Agradecemos a compreensão. on 2016-11-10T15:50:45Z (GMT) / Submitted by ANDERSON FIGUEIREDO DA COSTA null (and.kairos@hotmail.com) on 2016-11-22T17:09:03Z No. of bitstreams: 1 Dissertação 20161104 - Versão Final Corrigida.pdf: 5558976 bytes, checksum: 402eb9e3734833ebc7ccebf113844b8e (MD5) / Approved for entry into archive by Felipe Augusto Arakaki (arakaki@reitoria.unesp.br) on 2016-11-23T17:41:31Z (GMT) No. of bitstreams: 1 costa_af_me_guara.pdf: 5558976 bytes, checksum: 402eb9e3734833ebc7ccebf113844b8e (MD5) / Made available in DSpace on 2016-11-23T17:41:31Z (GMT). No. of bitstreams: 1 costa_af_me_guara.pdf: 5558976 bytes, checksum: 402eb9e3734833ebc7ccebf113844b8e (MD5) Previous issue date: 16-09-08 / Com o atual avanço de propriedades dos materiais, novas alternativas estão sendo buscadas para manufaturas desses materiais. Entre os processos, a usinagem se caracteriza por ser um processo que emprega milhões de pessoas. Entretanto para alcançar tais objetivos melhorias nas propriedades das ferramentas se faz necessária. Neste seguimento, os revestimentos vêm apresentando avanços significativos, como pode-se destacar o revestimento por CVD (deposição química a vapor) que permite que a ferramenta seja empregada nas temperaturas em torno de 1200ºC. Nesta mesma linha vale destacar o revestimento por PVD (deposição física a vapor) normalmente em uma única camada, o qual permite que a aresta de corte seja positiva, possa trabalhar com menor esforço de corte, e em temperatura aproximadamente em 700ºC. Este trabalho tem como objetivo analisar comparativamente o desempenho de ferramentas de metal duro revestidas pelo processo CVD e PVD no torneamento do aço ABNT 8620 sem uso de fluido de corte. Foram utilizadas duas pastilhas de metal duro revestidas pelo processo de PVD e CVD, com mesma geometria para efeito comparativo. A pastilha revestida por PVD tem espessura do revestimento de 3µm, enquanto que a pastilha revestida por CVD tem espessura do revestimento de 16µm. As pastilhas revestidas foram caracterizadas quanto a composição química dos elementos de revestimentos utilizando um microscópio eletrônico de varredura pela técnica de linescan e mapping. Posteriormente as ferramentas foram aplicadas ao torneamento nas velocidades de corte (Vc) entre 350 a 500m/min, avanço (f) de 0,20mm/rot e profundidade de corte (ap) de 1,00mm, utilizando um torno da marca ROMI, modelo GL240M. As caracterizações foram realizadas com uso de um microscópio óptico, microscópio eletrônico de varredura e um rugosímetro. Os resultados demonstraram que a ferramenta revestida pelo processo CVD apresenta um melhor rendimento, quando comparado ao processo PVD, este fato ocorreu porque a ferramenta revestida pelo processo CVD apresenta um revestimento multicamadas, possuindo um aporte térmico mais elevado, suportando assim, temperaturas de corte mais elevadas durante a usinagem e promovendo um menor desgaste de flanco e de superfície de saída. Portanto, este trabalho demonstra que para uso em uma indústria que torneia o aço ABNT 8620, as ferramentas revestidas com CVD apresentam melhor desempenho, levando a um menor consumo de pastilhas e uma expressiva redução de custos. / With the current advancement of material properties, new alternatives are being sought for manufacturing these materials. Among the processes, machining is characterized as a process that employs millions of people. However to achieve such goals improvements in the tools properties is necessary. In this follow-up, the coatings have shown significant advances, as can highlight the coating by CVD (chemical vapor deposition) that allows the tool to be used at temperatures around 1200°C. In the same line it is worth highlighting the coating by PVD (physical vapor deposition) usually in a single layer, which allows the cutting edge is positive, can work with less shear stress, and temperature approximately 700°C. This study aims at comparing the performance of carbide tools coated by the CVD process and PVD in the steel turning ABNT 8620 without the use of cutting fluid. We used two carbide inserts coated by the PVD and CVD process, with the same geometry for comparison purposes. The tablet is coated by PVD coating thickness of 3μm, while the tablet is coated by CVD coating thickness of 16μm. The coated tablets were characterized as the chemical composition of coatings elements using a scanning electron microscope for linescan technique and mapping. Subsequently the tools were applied to turning the cutting speed (Vc) between 350 to 500 m/min, feed (f) 0.20 mm/rev and depth of cut (ap) of 1.00mm using a lathe ROMI mark, GL240M model. The characterizations were carried out using an optical microscope, scanning electron microscope and roughness. The results demonstrated that the tool coated by the CVD process has a better performance when compared to PVD this occurred because the tool coated by the CVD process has a multilayer coating having a higher heat input, supporting thus cutting temperatures over high during machining and promote a smaller flank wear and output surface. Therefore, this work shows that for use in an industry that sidesteps steel ABNT 8620, tools coated with CVD have better performance, leading to lower consumption of pellets and a significant cost reduction.