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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
881

Propriedades eletrônicas e estruturais de nanoestruturas de carbono funcionalizadas para aplicação em sensores / Electronic and structural properties of functionalized carbon nanostrucutures for sensors applications

Menezes, Vivian Machado de 12 January 2012 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This work presents a study of properties of functionalized carbon nanotubes and graphene nanoribbons. We studied, by first principles simulations, the structural and electronic properties of functionalized nanotubes and interacting with molecules of biological interest. Furthermore, we analyzed the properties of these systems under the action of applied electric fields, noting changes on their behavior due the external perturbation. In the case of nanotubes interacting with anti-inflammatory nimesulide, the interaction is repulsive, resulting in energetically unstable systems, but which may have their behavior controlled by the external field. We noted that when the carbon nanotube interacts with the antimalarial primaquine, a strong bond between the systems occurs, where the presence of primaquine can modify the electronic properties of nanotubes. In the other hand, for the case of carbon nanostructures interacting with vitamins, the interaction is weak. We also evaluated the structural, electronic and magnetic properties of Ti and Mn doped carbon nanoribbons (or graphene nanoribbons) and properties of defective nanoribbons, by first principles simulations (code SIESTA), and analyzed the electronic transport properties of some of these systems, by tight-binding methods associated with Green s functions. We noted that there is an edge and sublattice effect in zigzag edged nanoribbons, where the properties of the systems can be modified depending on the defect location with respect to the edge. We demonstrate that carbon nanostructures can act as selective sensors of atoms or adsorbed molecules, besides representing a route to drug delivery. / Este trabalho apresenta um estudo de propriedades de nanotubos e nanofitas de carbono funcionalizados. Estudamos, via simulação de primeiros princípios, as propriedades estruturais e eletrônicas de nanotubos funcionalizados e interagindo com moléculas de interesse biológico. Analisamos, ainda, as propriedades destes sistemas sob a ação de campos elétricos aplicados, observando alterações em seus comportamentos devido à perturbação externa. No caso dos nanotubos interagindo com o anti-inflamatório nimesulida, a interação é repulsiva, resultando em sistemas energeticamente instáveis, mas que podem ter seu comportamento controlado pelo campo externo. Notamos que quando o nanotubo de carbono interage com o antimalárico primaquina, ocorre uma ligação forte entre estes sistemas, onde a presença da primaquina pode alterar as propriedades eletrônicas dos nanotubos. Já para o caso de nanoestruturas de carbono interagindo com vitaminas, a interação é fraca. Avaliamos também as propriedades estruturais, eletrônicas e magnéticas de nanofitas de carbono (ou nanofitas de grafeno) dopadas por átomos de Ti e Mn e propriedades de nanofitas defeituosas, por meio de simulações de primeiros princípios (código SIESTA), e avaliamos as propriedades de transporte eletrônico de alguns destes sistemas, por métodos tight-binding associados a funções de Green. Observamos que existe um efeito de borda e de sub-rede nas nanofitas de borda zigzag, onde as propriedades dos sistemas podem ser alteradas de acordo com a localização do defeito com relação à borda. Nós mostramos que as nanoestruturas de carbono podem agir como sensores seletivos de átomos ou moléculas adsorvidos, além de representarem uma rota de carreamento de fármacos.
882

Propriedades de transporte de um plano de grafeno com átomos adsorvidos /

Machado, Robyson dos Santos. January 2017 (has links)
Orientador: Antonio Carlos Ferreira Seridonio / Resumo: Esta tese é dedicada ao estudo teórico das propriedades de transp orte eletrônico do grafeno hosp edando um par de átomos adsorvidos em diferentes geometrias. Na primeira delas, verificamos a densidade lo cal de estados (LDOS) do plano de grafeno hos p edando um par de átomos adsorvidos, distantes entre si, no centro de uma célula hexagonal da rede. Nesta primeira configuração, efeitos de correlação revelaram uma es trutura multiníveis na LDOS e padrõ es de batimentos na densidade de estados (DOS) induzida. Amb os efeitos são anisotrópicos e o correm na vizinhança dos p ontos de Dirac. Em um segundo arranjo, estudamos a formação de estados ligados ao contínuo (BICs) adsorvendo um par de átomos em lados op ostos do plano de grafeno e colineares com o centro de uma célula hexagonal. Mostramos que nesta configuração a LDOS é caracterizada p or uma dep endência cúbica na energia e que um mecanismo de interferência Fano destrutiva assistida p or uma correlação de Coulomb nas impurezas leva a formação de BICs. Na terceira geometria, analisamos os efeitos do acoplamento não-lo cal de um par de átomos adsorvidos colineares a um átomo de carb ono da rede na LDOS do grafeno. Em tal arranjo, canais de tunelamento eletrônico distintos dão origem a um fator de interferência Fano q0, que se torna um parâmetro de controle natural do sistema. Verificamos três regimes distintos para o sistema: (i) quando q0 < qc1 (ponto crítico) uma dependência mista do pseudogap, ∆ ∝ | ε| , | ε| 2, leva o si... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: In this thesis we present a detailed theoretical study of the electronic transp ort prop erties of graphene systems hosting a pair of adatoms in distinct geometries. In the first one, where the adatoms are placed distant from each other at the center of the hexagonal cell, we verify multilevels struture in the lo cal density of states (LDOS) and b eat patterns in the induced density of states (DOS) profiles due to correlation effects. The b oth findings are anissotropic and o ccour near the Dirac p oint. In the second system, we study the formation of b ound states in the continuum (BICs) in a pair of adatoms on opp osite sides of the graphene sheet and colinear with the center of the hexagonal cell. In such a set, we show that the LDOS is caracterized by a cubic dep endence in energy and that the Fano destrutive interference assisted by Coulomb correlation in the adatoms gives rise to the BICs formation. In the third configuration, we analyze the effects of the nonlo cal coupling in a pair of adatoms collinear to a carb on atom of the graphene sheet. In such a geometry, distinct tunneling paths lead to a Fano factor of interferance q0, which becomes a natural control parameter of the system. In this sense, we verify three distinct regimes: (i) when q0 < qc1 (critical point) a mixed dependence of the pseudogap, ∆ ∝ | ε| , | ε| 2, gives rise to a phase presenting spin-degenerates BICs; (ii) near to q0 = qc1, we find a pseudogap ∆ ∝ | ε| 2 , where the system is drives to a quan... (Complete abstract click electronic access below) / Doutor
883

Bioélectronique graphène pour un interfaçage neuronal in-vivo durable / Graphene bioelectronics for long term neuronal interfacing in-vivo

Bourrier, Antoine 23 March 2017 (has links)
Le graphène, une couche monoatomique de carbone, est étudié comme matériau pourconstruire ou encapsuler des biocapteurs afin d’adresser les problèmes de durabilitérencontrés avec les implants intra-corticaux. Ces derniers sont des outils essentiels pour lesprojets médicaux de neuro-réhabilitation afin d’enregistrer les signaux de motoneuronesuniques dans le cerveau. Les implants actuels sont invasifs et leur efficacité est limitée dans letemps par la réaction de rejet des tissus. En combinant une synthèse de graphène optimiséeà cet usage (monocouche continue sur plusieurs cm²) et son intégration dans des capteursélectroniques ultra-sensibles, protégés par des polymères bioactifs, cette thèse propose unenouvelle approche pluridisciplinaire pour construire des implants offrant une meilleurebioacceptance. Au moyen de méthodes d’intégration innovantes et d’études ducomportement du graphène in-vivo et in-vitro, nous évaluons expérimentalement lafaisabilité d’intégration du graphène dans les futures interfaces cerveau machines pour desprojets médicaux au long terme. / Graphene, an atomically thin layer of carbon, is investigated as a biosensing andcoating material in order to address the long term durability issues of invasive intracorticalimplants. These devices are essential tools to record specific single motor neurons activity formedical applications aiming at healing neural injuries. Today’s implants suffer from their highinvasiveness. It is responsible for local inflammation that leads to the failure in unique neuronsactivity recordings in the motor cortex on a long term basis. By combining a monolayergraphene growth and transfer with an ultra-sensitive electronic integration and a biochemicalfunctionalization, this thesis proposes a new multidisciplinary approach to build intracorticalimplants with an improved bioacceptance. By using innovative methods of grapheneintegration in implants, and in-vitro and in-vivo studies to assess the reactions of living tissuesto graphene, we provide an overview of graphene’s potential contribution to future brainmachine interfaces for long term medical projects.
884

Produção de grafeno pela abertura de nanotubos de carbono auxiliada por líquido iônico e uso em nanocompósitos de resina epoxídica

Kleinschmidt, Ana Claudia January 2014 (has links)
No fim do século XX cresceu o interesse por materiais com potencial para aplicação na área da nanotecnologia. Um destes materiais é o grafeno (alótropo do carbono da espessura de um átomo), indicado para aplicações que exploram desde propriedades ópticas até mecânicas. Todavia, os métodos de produção estabelecidos até o momento geram normalmente um produto com alto grau de defeitos estruturais. Por isso, o objetivo deste estudo foi desenvolver um método mais brando para obtenção de grafeno, por meio do desenrolamento de nanotubos de carbono (NTC) de parede múltipla na presença de líquidos iônicos (LI) (que possuem caráter lubrificante e estabilizador) e adicioná-lo à resina epoxídica para avaliar seu efeito nas propriedades do nanocompósito. A metodologia consistiu em definir a rota a que a mistura NTC:LI (bis(trifluorometanosulfonil)imidato de 1-n-butil-3-metilimidazólio – BMImNTf2), na proporção 1:10, deveria ser submetida e depois avaliar variações para validação do método (alteração de temperatura, solventes – LI BMImCl e tolueno e nanocarga – grafite). As misturas de grafeno-NTC/LI produzidas foram adicionadas na proporção de 0,1% em massa de grafeno-NTC à resina epoxídica. A caracterização das misturas se deu pelas técnicas de microscopia eletrônica de transmissão (MET), espectroscopia Raman e microscopia de força atômica (AFM), e dos nanocompósitos, também por microscopia eletrônica de varredura (MEV), análise termogravimétrica (TGA), calorimetria diferencial exploratória (DSC), infravermelho (IV) análise dinâmico-mecânica (DMA) e ensaios mecânicos. A morfologia observada em MET e AFM evidenciou que a rota em que a mistura permaneceu 3 h em aquecimento e agitação magnética sob vácuo e 3 h sob sonificação resultou em grafeno de algumas camadas. Os resultados de Raman mostraram que foi produzido grafeno de boa qualidade, baseando-se na razão ID/IG. Nos nanocompósitos, confirmou-se que BMImNTf2 mantém as folhas de grafeno abertas. Já com BMImCl a morfologia dos NTC permanece inalterada, mas seu grau de emaranhamento é diminuído pela ação lubrificante deste LI, o que reflete em melhoria na resistência ao impacto. Os NTC sem a presença de um LI de forma geral não conferiram melhoria à matriz polimérica (ex: queda de 35% na dureza). / In the late twentieth century, the interest in materials with potential application in the nanotechnology´s field has increased. One of these materials is graphene (carbon allotrope of a single atom thickness), suitable for applications, which exploit properties such as optical or mechanical. However, the methods developed up to now to obtain graphene usually generate a product with high degree of structural defects. Therefore, the aim of this study was to produce graphene sheets through a milder route of unrolling multi-walled carbon nanotubes (CNT) in ionic liquids (IL; which have a lubricating and stabilizing character) and to add it to an epoxy resin to evaluate its effect on the nanocomposite properties. The methodology consisted of defining the route through which the 1:10 mixture of CNT:IL (1-n-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imidate - BMImNTf2) should be submitted, and then evaluate possible variations for validating the method (change in temperature, solvents - toluene and IL BMImCl and nanofiller - graphite). The produced graphene-CNT/IL mixtures were added at 0.1% by weight of graphene-CNT to epoxy resin. Characterization of the graphene/IL mixtures was done by transmission electron microscopy (TEM), Raman spectroscopy and atomic force microscopy (AFM), and the nanocomposites also by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), dynamical mechanical analysis (DMA) and mechanical tests. The morphology observed using TEM and AFM showed that the route based on 3 h under heating, stirring and vacuum, followed by 3 h of sonication leads to CNT unrolling. Raman spectra showed that the produced graphene was of good quality, based on the low ID/IG ratio. In the nanocomposites, CNT unrolling was confirmed when IL BMImNTf2 was used, yielding reasonable property improvements. In the case of IL BMImCl, the unrolling of the CNT did not occur, but the lubricant effect of the IL decreased the degree of entanglement, which increased its impact strength. Differently, the non-treated CNT generally reduced the properties of the polymer matrix, e.g. a 35% drop in hardness.
885

Strain engineering of graphene

Qi, Zenan 08 April 2016 (has links)
The focus of this thesis is on using mechanical strain to tailor the electronic properties of graphene. The first half covers the electro-mechanical coupling for graphene in different configurations, namely a hexagonal Y-junction, various shaped bubbles on different substrates, and with kirigami cuts. For all of these cases, a novel combination of tight-binding electronic structure calculations and molecular dynamics is utilized to demonstrate how mechanical loading and deformation impacts the resulting electronic structure and transport. For the Y-junction, a quasi-uniform pseudo magnetic field induced by strain restricts transport to Landau-level and edge-state-assisted resonant tunneling. For the bubbles, the shape and the nature of the substrate emerge as decisive factors determining the effectiveness of the nanoscale pseudo magnetic field tailoring in graphene. Finally, for the kirigami, it is shown that the yield and fracture strains of graphene, a well-known brittle material, can be enhanced by a factor of more than three using the kirigami structure, while also leading to significant enhancements in the localized pseudo magnetic fields. The second part of the thesis focuses on dissipation mechanisms in graphene nanomechanical resonators. Thermalization in nonlinear systems is a central concept in statistical mechanics and has been extensively studied theoretically since the seminal work of Fermi, Pasta, and Ulam (FPU). Using molecular dynamics and continuum modeling of a ring-down setup, it is shown that thermalization due to nonlinear mode coupling intrinsically limits the quality factor of nanomechanical graphene drums and turns them into potential test beds for FPU physics. The relationship between thermalization rate, radius, temperature and prestrain is explored and investigated.
886

Integration of liquid crystals with redox electrolytes in dye-sensitised solar cells

Bin Kamarudin, Muhammad Akmal January 2018 (has links)
This thesis examines the electro-optic, electric and electrochemical properties of liquid crystal (LC) materials in self-assembly systems, that is, liquid crystal-polymer electrolyte composites (LC-PEs), LC binary mixtures, and their potential application in dye-sensitised solar cells (DSSCs). The birefringence of LCs causes light modulation, which can be controlled by an applied voltage and electric field. In particular, the LCs are used as one of the components for the electrolyte redox couple which is responsible for charge transfer mechanism in DSSCs. In this work, LC-PEs were developed by dissolving LCs in polymer electrolytes; using a homologous series of cyanobiphenyls in a range of concentrations, alkyl chain lengths and dielectric permittivities. We found that doping the polymer electrolyte with 15% 4'-cyano-4'-pentylbiphenyl (5CB) improved ionic conductivity by up to 13 % compared to pure polymer electrolyte. Materials with positive dielectric permittivity and shorter alkyl chain length have been identified to be compatible with iodide/triiodide (I^-/I_3^-)-based polymer electrolytes. In DSSCs, 15% 5CB and 15% E7 LC-PEs exhibited the best efficiencies of 3.6 % and 4.0 %, respectively. In addition to LC-PEs, the self-assembly properties of smectic phase LCs were also utilised as templates for controlling the polymer structure in polymer electrolytes. A porous polymer network was prepared using various techniques including self-assembly, by applying an electric field and using a polyimide (PI) alignment layer. We found that the electrochemical and photovoltaic properties of these materials strongly correlated to the morphology/structure with the self-assembled structure, thus showing the best photovoltaic performance (5.9 %) even when compared with a reference solar cell (4.97 %). Finally, this thesis explores the interaction of LCs with graphene (Gr) in DSSC device architectures. Gr-based DSSCs were fabricated using different processing conditions, with the result being that Gr improved the performance of the DSSCs. The highest efficiency obtained was 5.48 % compared to the 4.86 % of a reference DSSC. The incorporation of LC-PEs in Gr-based DSSCs improved the performance of DSSCs was observed in devices with low concentrations of LCs due to the Gr inducing planar alignment of LCs. These results suggest a new strategy to improve DSSC efficiency by incorporating LC materials in the polymer electrolyte component. Even though these LCs are highly insulating, their self-assembly and dielectric polarisability help enhance ionic conductivity and optical scattering when doped into polymer electrolytes. This work can be extended in a fundamental way to elucidate the ionic conduction mechanism of LC-based electrolyte systems. Furthermore, it would be interesting if the benefits of using LC-PEs and smectic-templated polymer electrolytes (Sm-Pes) can be translated further in commercial electrochemical energy conversion systems.
887

System Reconstruction via Compressive Sensing, Complex-Network Dynamics and Electron Transport in Graphene Systems

January 2012 (has links)
abstract: Complex dynamical systems consisting interacting dynamical units are ubiquitous in nature and society. Predicting and reconstructing nonlinear dynamics of units and the complex interacting networks among them serves the base for the understanding of a variety of collective dynamical phenomena. I present a general method to address the two outstanding problems as a whole based solely on time-series measurements. The method is implemented by incorporating compressive sensing approach that enables an accurate reconstruction of complex dynamical systems in terms of both nodal equations that determines the self-dynamics of units and detailed coupling patterns among units. The representative advantages of the approach are (i) the sparse data requirement which allows for a successful reconstruction from limited measurements, and (ii) general applicability to identical and nonidentical nodal dynamics, and to networks with arbitrary interacting structure, strength and sizes. Another two challenging problem of significant interest in nonlinear dynamics: (i) predicting catastrophes in nonlinear dynamical systems in advance of their occurrences and (ii) predicting the future state for time-varying nonlinear dynamical systems, can be formulated and solved in the framework of compressive sensing using only limited measurements. Once the network structure can be inferred, the dynamics behavior on them can be investigated, for example optimize information spreading dynamics, suppress cascading dynamics and traffic congestion, enhance synchronization, game dynamics, etc. The results can yield insights to control strategies design in the real-world social and natural systems. Since 2004, there has been a tremendous amount of interest in graphene. The most amazing feature of graphene is that there exists linear energy-momentum relationship when energy is low. The quasi-particles inside the system can be treated as chiral, massless Dirac fermions obeying relativistic quantum mechanics. Therefore, the graphene provides one perfect test bed to investigate relativistic quantum phenomena, such as relativistic quantum chaotic scattering and abnormal electron paths induced by klein tunneling. This phenomenon has profound implications to the development of graphene based devices that require stable electronic properties. / Dissertation/Thesis / Ph.D. Electrical Engineering 2012
888

Polyamic acid-graphene oxide nanocomposite for electrochemical screening of antibiotic residues in water

Hamnca, Siyabulela January 2015 (has links)
>Magister Scientiae - MSc / Pollution of water sources, aquifers and wetland systems caused by industry, agriculture, and municipally treated wastewater is a worldwide problem that contributes to the scarcity of clean and potable water. Rivers, channels, lakes, oceans, and ground water are often contaminated by a variety of organic substances that can affect aquatic life and threaten human health. Organic compounds such as antibiotics that are not effectively removed by modern day water treatment technology are a growing threat to water quality and health. The emergence of antibiotics in the environment particularly aquatics have become a matter of concern as they may result in induction and spread of bacterial resistance which may be harmful to humans or animals. After administration, antibiotics for human use or their metabolites are excreted into the effluent and reach the sewage treatment plant (STP). Not all Antibiotics in sewage treatment plants are eliminated. Consequently they can pass through the sewage system and may end up in environmental and even potable water systems. Antibiotic residues have been reportedly found in places such as hospital wastewaters, wastewater treatment plants and surface waters all over the world with concentrations ranging from approximately 60-120000 ng/, 2-580 ng/L and 5-1300 ng/L respectively. The current methods that are used to detect antibiotics can be quite expensive and time consuming due to sample preparation (necessary for detection of very low concentrations of antibiotics in water) and technology used in the instruments. Electrochemical sensors and biosensors are simple systems, with high selectivity and sensitivity for individual measurements and cost effectiveness. The development of composites based on conductive phases dispersed in polymeric matrices has led to important advances in analytical electrochemistry. Polyamic acid and graphene oxide are both materials with well-defined electrochemistry and are easily processable in the design of various sensor formats. In this study we present a novel polyamic acid - graphene oxide (PAA/GO) electrode which was prepared for electrochemical screening of antibiotic residues in aqueous systems. Polyamic acid (PAA) and graphene oxide (GO) were successfully synthesized independently and characterized using SEM which was used to study the morphology of the PAA, FTIR spectroscopy to confirm chemical structures and functional groups as well as CV and SWV which were used to identify the unique electrochemical behavior of PAA and GO respectively. Polyamic acid-graphene oxide nanocomposite was prepared and characterized by CV, SWV, FTIR and SEM. The novel electrode (PAA/GO/SPCE) was prepared by electrochemically depositing PAA/GO (0.03 mg/mL) onto SPCE electrodes using 5 cycles between −1000 mV and 1000 mV at 50 mVs. The analytical performance of the electrochemical sensor towards detection of neomyxin and norlfoxacin was compared to standard Uv-vis spectroscopy method. The Uv-vis spectroscopy showed LOD of 1.61x10-5 M and 1.41x10-5 M for norfloxacin and neomycin respectively. The PAA/GO electrochemical sensor had a LOD of 3.37x10-7 M for norfloxacin and 1.066x10-6 M for neomycin. Sensitivity of the UV/vis method was comparable to electrochemical sensor sensitivity for neomycin and norfloxacin.
889

Graphenated organic nanoparticles immunosensors for the detection of TB biomarkers

Mgwili, Phelisa Yonela January 2017 (has links)
Magister Scientiae - MSc (Chemistry) / Pulmonary Tuberculosis (TB) a disease second to HIV/AIDS is a global health problem that arises in two states; as an active state and as a latent state. Diagnosis of active TB is tedious and requires expensive procedures since there is no recognizable method for the sole detection of active TB. The current diagnosis consists of chest X-rays and multiple sputum cultures used for acid-fast bacilli detection. The TB diagnosis of children is particularly difficult which further complicates the diagnosis. Thus, rapid identification of this pathogen is important for the treatment and control of this infection to allow effective and timely therapy. In an effort to solve this issue, this study reports the development of immunosensors constructed with electroactive layers of amino groups functionalized graphene oxide (GO) doped respectively with green synthesized zinc oxide (ZnO NPs) nanoparticles and silver (Ag NPs) nanoparticles on glassy carbon electrodes. The surface morphology of GO, ZnO NPs, Ag NPs and their composites was revealed by employing High-Resolution Transmission Electron Microscopy (HR-TEM) and High-Resolution Scanning Electron Microscopy (HR-SEM) while the composition and structure of these materials were studied using Fourier Transform Infra-Red Spectroscopy (FTIR). The resultant graphene oxide-metallic composites were covalently attached with CFP-10 and/or ESAT-6 antibodies to achieve the electrochemical detection. The immunosensor was then used for the impedimetric and amperometric detection of anti-CFP-10 and/or anti-ESAT-6 antigens in standard solutions.
890

Propriedades mecânicas e eletroquímicas de revestimento compósito com incorporação de óxido de grafeno

Cardoso, Henrique Ribeiro Piaggio January 2015 (has links)
O aumento das preocupações com o meio ambiente tem trazido à indústria de tratamento de superfícies novos desafios quanto ao desenvolvimento de revestimentos com maior desempenho quanto à resistência à corrosão e ao desgaste, observando a redução do impacto ambiental. Neste contexto, o objetivo do presente trabalho é obter um filme compósito à base de silano com incorporação de partículas de óxido de grafeno visando o aumento da resistência à corrosão e ao desgaste da liga de alumínio AA 2024-T3. A liga de alumínio AA 2024-T3 é um material bastante usado na indústria aeronáutica devido às propriedades mecânicas e à baixa densidade. Contudo, essa liga não oferece a resistência à corrosão e ao desgaste exigidos para aplicação na indústria aeronáutica, sendo necessário o emprego de revestimentos protetores. Dentre os revestimentos propostos para essa aplicação os revestimentos híbridos têm sido estudados, e mais recentemente a incorporação de partículas à essa matriz tem sido proposta visando melhorar as propriedades desses filmes. Nesse trabalho os revestimentos compósitos de matriz híbrida com incorporação de óxido de grafeno foram obtidos pelo processo de sol-gel a partir de um sol contendo os precursores alcoóxidos tetraetoxisilano (TEOS) e 3-trimetoxisilil-propil-metacrilato (MAP) com dispersão de partículas de óxido de grafeno em diferentes concentrações (1 g.L-1, 0,5 g.L-1, 0,25 g.L-1 e 0 g.L-1). Os filmes foram obtidos empregando-se o método de dip-coating à temperatura ambiente, com velocidade de retirada de 10 cm.min-1. O óxido de grafeno utilizado foi caracterizado quanto à estrutura utilizando as análises de FTIR, Raman, TGA e microscopia eletrônica de varredura de alta resolução. Para avaliar a estrutura do filme compósito obtido foram utilizadas as análises de FTIR, Raman e TGA. Microscopia eletrônica de varredura de alta resolução foi usada a fim de verificar a uniformidade do filme e avaliar a dispersão das partículas no filme. Os ensaios de polarização potenciodinâmica e impedância eletroquímica foram utilizados para analisar o comportamento referente à corrosão. Avaliou-se também a molhabilidade dos filmes, pelo método da gota séssil. As propriedades mecânicas do filme foram avaliadas empregando-se o ensaio de desgaste pela técnica de esfera sobre plano e teste de adesão. Nas condições estudas, a adição das partículas de óxido de grafeno não alterou a resistência à corrosão, contudo evidenciou-se uma contribuição positiva quanto ao aumento da resistência ao desgaste do filme. / The growing concern with the environment has created new challenges to the surface treatment industry, encouraging the development of coatings with a better performance in regards to the mechanical resistance and corrosion properties, observing the reduction of the environmental impact. In this context, this work aims to make a composite coating with graphene oxide charge to improve the corrosion and wear resistance in aluminum alloy AA 2024-T3. The aluminum alloy AA 2024-T3 is a material used in the aeronautics industry due to its low density and good mechanical proprieties. However, this alloy does not have the corrosion and wear resistance required by the aeronautics industry, requiring the use of protective coatings. Among the protective coatings proposed for this application, the hybrid films have been studied and more recently the incorporation of particles has been proposed to improve the proprieties of this film. In this work the hybrid matrix composite coating with incorporation of graphene oxide was obtained by sol-gel process from a sol containing alkoxide precursors Tetraetoxisilano (TEOS) and 3-(trimetoxisililpropil) metacrylate (MAP) with graphene oxide dispersion in different concentrations (1 g.L-1, 0,5 g.L-1, 0,25 g.L-1 e 0 g.L-1). The films were obtained using the dip-coating method in room temperature with 10 cm.min-1 of removal rate. For the characterization of the graphene oxide structure FTIR, Raman, TGA and scanning electron microscope were used. To measure the structure of composite films proprieties FTIR, Raman and TGA were used. In addition, the scanning electron microscope was used on composite film on aluminum alloy in order to verify the uniformity of film and to assess the behavior of the particles on film. The potentiodynamic polarization and the electrochemical impedance were used to analyze the behavior against corrosion. To measure the wettability contact angles measured by the sessile drop method were used. The film was examined for mechanical proprieties with the ball-on-plate and with the adhesion test. In the studied conditions, the adding of the particles of graphene oxide did not change the corrosion resistance, but it showed a positive contribution to the wear resistance.

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