A madeira maciça é um compósito polimérico natural que pode sofrer tratamentos para atender a diversas especificações técnicas. Uma característica da madeira é a sua higroscopicidade. A madeira úmida é vulnerável ao ataque de térmitas e fungos, além de perder estabilidade dimensional. Os tratamentos mais usados são a impregnação e/ou o revestimento com tintas e vernizes. Uma técnica promissora para o revestimento de madeira maciça é o plasma frio ou descarga luminescente. Neste trabalho produziu-se plasmas frios através de descargas elétricas luminescentes em gases rarefeitos. Os precursores gasosos usados foram o etileno, acetileno, 1-buteno, e vapor de metil metacrilato e de acetato de vinila. A superfície de madeira maciça tratada por estes plasmas ficaram hidrofóbicas, sendo que os melhores resultados foram alcançados usando 1-buteno como gás precursor. Apesar do tratamento promover repelência à água, a superfície tratada continuou permeável ao vapor d\'água. Com o emprego de uma mistura gasosa formada por vapor de TEOS e O2, foi possível constatar a ineficiência da descarga luminescente capacitiva em revestir o interior de orifícios em madeira. A deposição de filmes finos a partir de plasmas de 1-buteno foi caracterizada, tendo apresentado propriedades distintas do polímero convencional. O filme depositado por plasma apresentou hidrofobicidade, resistência química, insolubilidade em solventes comuns, e resistência contra teste acelerado de intemperismo. A espectroscopia de infravermelho e a análise elementar também revelaram diferenças entre os filmes convencional e depositado por plasma. As reações químicas no plasma podem ser controladas através de ajustes na potência transferida ao reator, pressão da câmara, vazão dos gases, e tempo de exposição à descarga. Com o uso de plasmas menos energéticos é possível produzir filmes poliméricos com estruturas menos entrecruzadas. Duas técnicas distintas foram testadas neste trabalho: o plasma capacitivo e o jato de plasma. Ambas as técnicas são promissoras em função do baixo nível de vácuo necessário, baixas freqüências, pequeno consumo de energia, ausência de poluição e solventes, e o uso de reagentes disponíveis em escala industrial. / Solid wood is a natural polymer composite that can be subjected to a wide variety of treatments to make it suitable for specific technical applications. The greatest disadvantage of solid wood is its hygroscopicity. Moist wood is vulnerable to attack by fungi and termites, and loses its dimensional stability. The most widely used treatments for solid wood are impregnation and coating with paint and varnish. A promising future technique for solid wood surface coating is a plasma treatment in a glow discharge. Cold plasmas were produced by electrical glow discharges in a gas medium at reduced pressure. The precursor gases used were ethylene, acetylene, 1-butene, and vapor of vinyl acetate. The treatment caused the solid softwood surface to become hydrophobic; 1-butene-plasma produced the best results. Although the surface plasma treatment resulted in water repellence, permeability to water vapor remained. Using a mixture of tetraethyl orthosilicate vapor (TEOS) and oxygen (O2) it was possible to investigate the inability of the glow discharge to coat the surface of wood orifices. Deposition of non-conventional polymeric thin films were observed on solid wood substrate after injecting a 1-butene-argon gas mixture into a glow discharge chamber. The deposited film showed water repellence, chemical resistance, insolubility in most common organic solvents and some protection against weathering. Infrared analyses revealed differences between conventional and plasma polymerized 1-butene. Plasma chemistry can be controlled by external conditions of plasma, such as input power, gas flow rate, pressure, and the time of exposure. Using low energetic plasmas the deposited film can be polymer like with a less crosslinked structure. Two different techniques - known capacitive coupled plasma and plasma jet - were tested in this study. Both these techniques appear promising in view of the low vacum level and low frequency, low power supply required, the lack of pollutants and solventes, and the use of industrial chemicals.

[pt] O processo de revestimento por extrusão é usado na manufatura de diversos produtos. A espessura da camada de líquido depositada é determinada pela vazão de líquido e pela velocidade do substrato, e independe das outras variáveis de operação do processo. Um importante limite de operação deste processo é a espessura mínima que pode ser depositada sobre um substrato a uma determinada velocidade, geralmente chamado de limite de vazão mínima. Para líquidos Newtonianos, o mecanismo que define este limite é o balanço de forças viscosas, de capilaridade e inerciais no escoamento. A pesar da maioria dos líquidos usados em processos de revestimento industriais serem soluções poliméricas ou dispersões que possuem comportamento não Newtoniano, a maioria das análises de limites de operação do processo de revestimento por extrusão são restritas à líquidos Newtonianos. No caso particular de soluções poliméricas as tensões elásticas podem alterar o balanço de forças em diversas regiões do escoamento e consequentemente os limites de operação do processo. Neste trabalho o limite de vazão mínima no caso de líquidos não Newtonianos é analisado teoricamente e experimentalmente. Os modelos constitutivos de Oldroyd-B e Giesekus, que descrevem o comportamento de soluções poliméricas diluídas, em conjunto com as equações de conservação de massa e quantidade de movimento são usados para descrever o escoamento bidimensional que ocorre no processo de revestimento por extrusão. O sistema de equações diferenciais foi resolvido usando o método de elementos finitos. Os resultados mostram como as propriedades viscoelásticas influenciam a distribuição de tensão no escoamento e o balanço de forças nas proximidades da superfície livre à jusante da região de deposição. / [en] Slot coating is a common method in the manufacture of a wide variety of products. The thickness of the coated liquid layer is set by the flow rate fed to the coating die and the speed of the substrate, and is independent of other process variables. An important operating limit of slot coating is the minimum thickness that can be coated at a given substrate speed,generally referred to as the low- flow limit. For Newtonian liquids, the mechanism that defines this limit balances the viscous, capillary and inertial forces in the flow. Although most of the liquids coated industrially are polymeric solutions and dispersions that are not Newtonian, most of the previous analyses of operability limits in slot coating dealt only with Newtonian liquids. In the case of liquids made non- Newtonian by polymer viscoelasticity, stresses can alter the force balance in various parts of the coating bead and consequently the onset of instability. In this work, the low-flow limit in cases of non-Newtonian liquids is examined by both theory and experiment. The Oldroyd-B and Giesekus constitutive equations that approximate viscoelastic behavior of polymer solutions were used, together with momentum and continuity equations, to model two-dimensional flow in the downstream part of a slot coating bead. The equation system was solved with the Finite Element Method. The results show how the viscoelastic properties can affect the stress field in the liquid and the force balance near and at the downstream meniscus, thereby illustrating how non-Newtonian behavior can alter the flow instabilities that determine the coating window of slot coating. The flows themselves were visualized by video microscopy and the low-flow limit was found by observing, at given substrate speed, the feed rate at which the flow becomes unstable. Different solutions of low molecular weight polyethylene glycol and high molecular weight polyethylene oxide in water were used in order to evaluate the effect of mildly viscoelastic behavior on the process.

The work in this thesis examines the effects of the application of oxide coatings on the performance of the single crystalline silicon photovoltaic solar cells. A variety of potential oxide materials for solar cells performance enhancement are investigated. These films are silicon oxide, titanium oxide and rare earth ion-doped gadolinium oxysulfide phosphor. This study compares the electrical characteristics, optical properties and surface chemical composition of mono-crystalline silicon cells before and after coating. The first study investigates the potential for using single and double layers of silicon oxide films produced by low-temperature Plasma Enhanced Chemical Vapour Deposition (PECVD) using tetramethylsilane as a silicon precursor and potassium permanganate oxidising agent for efficiency enhancement of solar cells at low manufacturing cost. Deposition of the films contributes to the increase of the conversion energy of the solar cells on one hand while the variety of colours obtained in this study can be of great importance for building-integrated photovoltaic application on the other hand. The obtained results demonstrated a relative enhancement of 3% in the conversion efficiency of the crystalline silicon solar cell. In the second study, the effects of using a single layer of titanium oxide and a stack of silicon oxide and titanium oxide on the performance of solar cell are demonstrated. Moreover, this study shows the use of different sputtering configurations and oxidation methods. The experimental results showed a relative enhancement of 1.6% for solar cells coated with a stack of silicon oxide/titanium oxide. In the third study, silicon cells were coated with a luminescent layer consisting of down-converting phosphor, gadolinium oxysulfide doped with erbium and terbium, and a polymeric binder of EVA using doctor-blade screen printing technique. A relative enhancement of 4.45% in the energy conversion efficiency of PV solar cell was achieved. Also, the effects of combining silicon oxide layers together with the luminescent composite are also presented in this study.

Metal oxide thin films serve as critical components in many modern technologies, including microelectronic devices. Industrial state-of-the-art production utilizes vapor-phase techniques to make high-quality (dense, smooth, uniform) thin film materials. However, vapor-phase techniques require large energy inputs and expensive equipment and precursors. Solution-phase routes to metal oxides have attracted great interest as cost-effective alternatives to vapor-phase methods and also offer the potential of large-area coverage, facile control of metal composition, and low-temperature processing. Solution deposition has previously been dominated by sol-gel routes, which utilize organic ligands, additives, and/or solvents. However, sol-gel films are often porous and contain residual carbon impurities, which can negatively impact device properties. All-inorganic aqueous routes produce dense, ultrasmooth films without carbon impurities, but the mechanisms involved in converting aqueous precursors to metal oxides are virtually unexplored. Understanding these mechanisms and the parameters that influence them is critical for widespread use of aqueous approaches to prepare microelectronic components. Additionally, understanding (and controlling) density and composition inhomogeneities is important for optimizing electronic properties. An overview of deposition approaches and the challenges facing aqueous routes are presented in Chapter I. A summary of thin film characterization techniques central to this work is given in Chapter II. This dissertation contributes to the field of solution-phase deposition by focusing on three areas. First, an all-inorganic aqueous route to high-κ metal oxide dielectrics is developed for two ternary systems. Chapters III and IV detail the film formation chemistry and film properties of lanthanum zirconium oxide (LZO) and zirconium aluminum oxide (ZAO), respectively. The functionality of these dielectrics as device components is also demonstrated. Second, the impact of steam annealing on the evolution of aqueous-derived films is reported. Chapter V demonstrates that steam annealing lowers processing temperatures by effectively reducing residual counterion content, improving film stability with respect to water absorption, and enhancing dielectric properties of LZO films. Third, density and composition inhomogeneities in aqueous-derived films are investigated. Chapters VI and VII examine density inhomogeneities in single- and multi-metal component thin films, respectively, and show that these density inhomogeneities are related to inhomogeneous metal component distributions. This dissertation includes previously published coauthored material.

The photocatalytic properties of titanium dioxide have been widely studied over recent decades since the discovery in 1972 of water photolysis by TiO2 electrodes. There are a number of different TiO2 polymorphs. Rutile and anatase are the most studied due to their chemo-physical properties. Under ultraviolet light, TiO2 is able to absorb photons, creating a charge separation on the surface, an electron and a positive “hole”. This electron-hole pair then reacts with water and oxygen, generating radicals, very unstable and reactive species which show great potential for neutralisation of pollutants. In the introduction the state of art of photocatalysis; chemo-physical principles, applications and current analysis are described. A number of protocols to test photoactivity are discussed with particular emphasis on the importance of gas phase reactions. The development of a novel system to study gas phase reactions by mass spectrometry was explored, detailing the conditions and parameters that were optimised. This instrument was used to analyse photocatalytic properties of TiO2 powders and photocatalytic coatings under different UV light conditions. The results showed how TiO2 in the form of anatase and rutile removed nitrogen and carbon dioxide under different UV light sources, with anatase being more effective. A comprehensive study of several commercially available TiO2 powders and coatings was performed to identify the differences between photocatalytic properties, using electron microscopy, Raman and UV-vis diffusive spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy. An important question that was answered in this thesis is whether the physical properties of nanoparticles or their electronic properties are critical for their photocatalytic behaviour. Results for anatase powders of different particle size and surface area showed how the positioning of their electronic band gap with the wavelength of the UV light source was fundamental for an effective photocatalyic process. In order to improve the photocatalytic process, “self-doping” TiO2 was investigated. Different reduction temperatures were studied to generate the best ratio of Ti3+-Ti4+ that stabilised the charge distribution process to maximize the electron-hole pairs generated per photon in the gas phase. From a wide range of reduction temperatures, titanium sub-oxime reduced at 400 oC showed the best performance in removing carbon dioxide. In the application of TiO2 for the built environment, the best commercially available TiO2 powder, anatase P25 was applied with two different techniques. Electrophoretic deposition has the potential to scale up the process for prefabricated panels in construction. Solvent, iv deposition time, voltage and substrate were optimised. The resulting photoactivity of the coatings was evaluated showing a higher efficiency than a compressed pellet of anatase P25. The final part of the thesis was dedicated to the formulation and application of a photocatalytic enhanced lime based coatings for the built heritage. The use of calcium hydroxide dispersions is widely used in the conservation and restoration community, reinforcing limestone when it carbonates. Anatase P25, was added to improve the performance in polluted atmospheres, acting as a sacrificial barrier. Results showed that by adding anatase to the formulation, calcium hydroxide reacted preferentially with sulphur dioxide over carbon dioxide. The final product in the formulation with anatase was calcium sulphate, whereas the final product for the calcium hydroxide formulation was calcium sulphite. Finally, a general discussion of the results is presented and the conclusions of this research are drawn. Recommendations for further work are presented in the last chapter.

Metallic interconnects in intermediate temperature solid oxide fuel cells (IT-SOFC) stacks form Cr2O3 scales on their surface. Such oxide scales can be further oxidized to Cr6+ containing gaseous species that migrate and deposit at the cathode triple phase boundaries, causing significant degradation in the performance of the SOFCs. This phenomenon is termed as ‘Cr-poisoning’. A solution to this problem is the application of coatings on the interconnects that act as a diffusion barrier to Cr migration. Two different Cu/Mn spinel compositions, Cu1.3Mn1.7O4 and CuMn1.8O4, were studied as coating materials. Dense coatings were deposited on both flat plates and meshes by electrophoretic deposition (EPD) followed by subsequent thermo-mechanical or thermal densification steps. At room temperature, Cu1.3Mn1.7O4 coatings were found to have a mixture of CuO and spinel phases, while CuMn1.8O4 coatings were found to have a mixture of Mn3O4 and spinel phases. However, CuMn1.8O4 is a pure spinel phase between 750 °C and 850 °C. After densification processing and high temperature oxidation, a Cr2O3 layer was formed at the coating/alloy interface, which partially reacted with the spinel coatings to form a dense cubic spinel layer of the general composition (Cu,Mn,Cr)3-xO4. In addition, Cr-rich precipitates, formed in the dense layer close to coating/alloy interface. It is believed that these are Cr2O3 precipitates, formed when the solubility of Cr in the spinel phase is reached. Solubility experiments using powders showed that 1 mole of CuMn1.8O4 can effectively getter 1.83 moles of Cr2O3 at 800°C. Electrical conductivity of (Cu,Mn,Cr)3-xO4 was found to be at least two orders of magnitude higher than that of Cr2O3. The coatings acted as an effective Cr getter whose lifetime depends on the oxidation temperature, coating thickness, and the overall porosity in the coating. In-cell electrochemical testing showed that the CuMn1.8O4 coatings on Crofer 22 APU meshes performed significantly better than commercial Cu/Mn spinel coatings. The CuMn1.8O4 coatings gettered Cr effectively for 12 days at 800 ºC, leading to no performance loss of the cell due to Cr-poisoning. Significantly longer lifetime can be achieved at 750 ºC or lower, which is the target operational temperature regime of IT-SOFCs.

Submitted by Maicon Juliano Schmidt (maicons) on 2015-05-08T19:21:55Z No. of bitstreams: 1 Mateus Rosa.pdf: 3353593 bytes, checksum: 4d6dedf924e0718583cacfeb4529296e (MD5) / Made available in DSpace on 2015-05-08T19:21:55Z (GMT). No. of bitstreams: 1 Mateus Rosa.pdf: 3353593 bytes, checksum: 4d6dedf924e0718583cacfeb4529296e (MD5) Previous issue date: 2013-12-19 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / PROSUP - Programa de Suporte à Pós-Gradução de Instituições de Ensino Particulares / O Brasil passa por excelente momento na construção civil. Esse fato faz com que ocorra grande demanda de materiais, consequentemente grande consumo de matérias-primas e grande impacto ambiental. Para a produção de argamassas de revestimentos, normalmente, é utilizada areia natural, proveniente de depósitos aluvionares. Este tipo de matéria-prima está escasso, possui alto custo, e afeta diretamente o meio-ambiente por ser uma matéria prima não renovável. Uma possível alternativa de agregado miúdo, para uso em argamassa de revestimento, é a areia de britagem, que já é utilizada como agregado miúdo para concretos. Este estudo avalia o comportamento de argamassas produzidas com areias de britagem. O objetivo é comparar o comportamento de uma argamassa de cimento, cal e areia proveniente de britagem de rocha basáltica, com a mesma argamassa utilizando-se areia natural, sendo adicionadas às duas areias, microfinos provenientes da própria britagem da rocha basáltica. Foram adicionados cinco diferentes porcentagens de microfinos, formando dez traços de areias, sendo cinco traços com areia natural de leito de rio (areia aluvionar) e outros cinco traços com areia de britagem de rocha basáltica proveniente de britador VSI, material normalmente classificado como finos de pedreira. Os aglomerantes utilizados foram o CP II Z- 32 e cal CH-I. O traço adotado foi de 1:1:6 em volume de cimento, cal e areia.Foi possível comparar e analisar a retração das argamassas fazendo relação com a fissuração. Os resultados alcançados neste trabalho mostram que é tecnicamente viável a substituição de areia natural por areia de britagem de rocha basáltica em argamassas de revestimento, com percentual de microfinos de 10%. Entretanto, são necessários estudos complementares para melhorar a granulometria e a forma das partículas da areia de britagem, permitindo um melhor acabamento superficial do revestimento e buscando viabilizar sua utilização sem a necessidade de acrescentar microfinos à areia de britagem para atingir um teor de 10%. / Brazil is going through a great time in construction, having an increase in demand of raw materials and a huge impact in the whole environment. In production of mortar coatings, it is commonly used natural sand from alluvial deposits. This type of raw material has a high cost, and affects directly the environment because it is a non-renewable. A possible alternative to fine aggregate are crushed aggregates, which is already used as aggregate for concrete. This research evaluates the behavior of mortars produced with basalt crushed fine aggregates. The objective is to compare the behavior of a cement, lime and sand mortar using crushed aggregates made from basaltic rock, with the same mortar proportion using natural sand. In all mortars microfine coming from the crushing of basaltic rock (using a VSI crusher) were added in five different percentages, 5 with natural sand and 5with crushed fine aggregates of basaltic rock. It was used CP II Z- 32 cement and CH-I lime, producing 1:1:6 cement, lime and sand mortars. It was analyzed the shrinkage and cracking of mortars. Results show that it is possible to replace natural sand by crushing basalt aggregates in a mortar coating using 10% of microfine. It is highly recommended to make complementary studies to improve the size distribution and shape of the crushed sand to provide a better surface finish to the coating and seeking allow their use without need to increase the powdery material to achieve the percentage of 10% of microfine.

Submitted by Patrícia Valim Labres de Freitas (patricial) on 2016-04-05T18:36:31Z No. of bitstreams: 1 Mauricio Schafer_.pdf: 3502667 bytes, checksum: bef575d3f673b57858290149f4ca04ed (MD5) / Made available in DSpace on 2016-04-05T18:36:31Z (GMT). No. of bitstreams: 1 Mauricio Schafer_.pdf: 3502667 bytes, checksum: bef575d3f673b57858290149f4ca04ed (MD5) Previous issue date: 2015-10-28 / itt Performance - Instituto Tecnológico em Desempenho da Construção Civil / UNISINOS - Universidade do Vale do Rio dos Sinos / Uma solicitação extrema a que uma alvenaria pode ser submetida é a decorrente de incêndios, que se destacam pelo grande potencial de degradação. Os revestimentos de argamassa são normalmente aplicados sobre substratos e, por comporem a última camada da alvenaria, se tornam mais suscetíveis às elevadas temperaturas. O estudo das alterações macro e microestruturais das argamassas podem auxiliar na identificação dos níveis de temperatura a que a estrutura foi submetida ao longo de um incêndio, permitindo um melhor diagnóstico sobre o sinistro e uma melhor estimativa sobre o nível de danos da estrutura de concreto e demais componentes da edificação. Partindo deste contexto, esta pesquisa tem como objetivo a análise da influência de elevadas temperaturas em um revestimento de argamassa. O programa experimental desenvolvido possui duas etapas: a primeira utilizando-se argamassas de revestimento aplicadas sobre blocos cerâmicos submetidos, em uma mufla, a temperaturas de 100, 300, 500, 700, e 900ºC, e caracterizados com relação a sua macroestrutura (resistência de aderência, absorção de água e velocidade de propagação da onda) e microestrutura (microscopia eletrônica de varredura e porosimetria por intrusão de mercúrio). A segunda etapa consiste no ensaio de paredes de alvenaria, construídas com o mesmo bloco cerâmico e a mesma argamassa da etapa anterior, em um forno que simula a ação de incêndio, especificado pela NBR 10636 (ABNT, 1989). Nas temperaturas até 300ºC houve uma melhoria nas propriedades das argamassas, já a partir da temperatura de 500ºC ocorreu uma degradação das argamassas e do revestimento, com queda de revestimento a partir da temperatura de 700ºC. Embora os procedimentos utilizados para o aumento da temperatura em mufla e em forno tenham ciclos de aquecimento distintos, não foram constatadas diferenças expressivas entre os resultados de ensaios em revestimentos submetidos a aquecimento em mufla e os submetidos ao forno simulando o incêndio. / An extreme request that masonry can be submitted is the result of fires that stand out for great potential of degradation. The mortar coatings are typically applied to substrates, and compose the last layer of masonry, become more susceptible to elevated temperatures. The study of changes macro and microstructure of the mortars can help identify temperature levels to which the structure was subjected over a fire, enabling a better diagnosis of the accident and a better estimate of the level of damage of the concrete structure and other components of the building. From this context, this research aims to analyze the influence of high temperatures in a mortar coating. The experimental program has two steps: first using a mortar coating applied over subjected ceramic blocks in a muffle furnace at temperatures of 100, 300, 500, 700, and 900°C, and characterized with regard to its macrostructure (adhesion resistance, water absorption and speed wave propagation) and microstructure (scanning electron microscopy and mercury intrusion porosimetry). The second step consists in testing masonry walls built with the same ceramic block and the same mortar in an oven to simulate the action of fire, specified by NBR 10636 (ABNT, 1989). In temperatures to 300°C there was an improvement in the properties of mortars, already from 500°C temperature occurred the deterioration of the mortar and coating, coated drop from the temperature of 700°C. Although the procedures used for increasing the temperature in a muffle furnace and oven have separate heating cycles, no significant differences observed between the test results on coatings.

O cenário atual da construção civil tem se caracterizado pelo uso crescente de novos produtos, materiais e tecnologias construtivas. Simultaneamente, a adoção de novas técnicas em detrimento a pouca abordagem científica e às falhas de projeto, execução e planejamento de obra têm colaborado para a ocorrência de manifestações patológicas. O desempenho do edifício resulta da contribuição individual de cada um dos materiais e elementos que o constituem, mas também depende do efeito gerado quando todo o conjunto é solicitado. Caso haja incompatibilidade entre as condições de deformação da estrutura de concreto, a capacidade de acomodar deformações da alvenaria e das camadas de argamassa pode desencadear-se desde pequenas fissuras no revestimento, rupturas na alvenaria até mesmo o colapso total da parede, gerando além de elevados custos e descrédito para as construtoras, principalmente, desconforto ao usuário. Atualmente existem diversas técnicas construtivas de reforço/reabilitação, de forma a distribuir tensões, compatibilizar deformações e garantir o desempenho à tração do revestimento de argamassa. Entre estas técnicas ressalta-se o uso de telas metálicas, que no Brasil é amparado por uma normalização ainda incipiente. Embora este uso seja recomendado, não há consenso quanto aos métodos executivos e parâmetros técnicos da tela metálica mais indicados para cada aplicação. Nesse contexto, o trabalho em questão, julgou importante contribuir para a avaliação do desempenho de revestimentos de argamassa com reforço de tela metálica e apresenta três propostas. Uma delas foi o ensaio de tração por compressão diametral, o qual se mostrou viável para avaliar a eficiência do uso de tela no incremento de resistência da argamassa, no entanto, permite ponderações restritas ao parâmetro de carga de ruptura. O ensaio de tração direta proposto para caracterizar o revestimento de argamassa reforçado com tela metálica, aplicado sobre a interface alvenariaestrutura, embora tenha execução complexa e demande mais tempo, apresentou variabilidade satisfatória e mostrou-se capaz para avaliar além da carga a resistência à tração. Por fim, o ensaio de tração na flexão em 4 pontos foi considerado apto para a caracterizar argamassas reforçadas com tela, diante da fácil aplicabilidade, com tamanho menor dos CP’s e variabilidade reduzida. Então foi usado para avaliar a influência de diferentes tipologias de telas metálicas e posicionamento delas na argamassa no desempenho à tração do revestimento. / The current scenario of the construction has been characterized by the increasing use of new products, materials and construction technologies. Simultaneously, the adoption of new techniques to the detriment a little and scientific approach to design failures, execution and construction management have contributed to the occurrence of pathological manifestations. The building performance results of the individual contribution of each one of the materials and elements constitute, but also depends on the effect generated when the whole set is requested. If there is incompatibility between the deformation conditions of the concrete structure, the ability to accommodate deformations of the masonry and layers of mortar, this may unleash from small cracks in the coating, breaks in the masonry even total collapse of the wall, generating high costs and discredit to the builders, mainly discomfort to the user. Nowadays there are many construction techniques reinforcement / rehabilitation, in order to distribute tensions, compatible deformations and guarantee performance to pull the mortar coating. Among these techniques emphasizes the use of metal mesh, which in Brazil is supported by an incipient normalization. Although this use is recommended, there is no consensus on the executive methods and technical parameters of the metal mesh best suited for each application. In this context, the work in question, considered it important to contribute to the evaluation of mortar coatings performance with metal mesh reinforcement and presents three proposals. One was the indirect tensile (Brazilian) test, which proved feasible to evaluate the use efficiency screen on mortar strength increase, however, allows considerations restricted to the breaking load parameter. The tensile direct test proposed to characterize the reinforced mortar coating metal screen applied to the masonry structure interface, although it has complex execution and demands more time presented satisfactory variability and shown to be able to evaluate the load and also the resistance to traction. Finally, the tensile test in bending at 4 points was considered suitable for the characterize mortars reinforced with screen, due to the easy applicability, have smaller size specimens and reduced variability. Then it was used to evaluate the influence of different types of metal mesh and positioning them in the mortar in performance to coating traction.

Os revestimentos poliméricos podem atuar como uma barreira física entre os íons agressivos e o substrato metálico. Porém, uma exposição prolongada pode causar danos ao revestimento polimérico, conduzir a uma redução contínua do efeito barreira e por consequência a perda da proteção contra a corrosão. A utilização de nano materiais pode atuar aumentando o efeito barreira, proporcionando um aumento no caminho de difusão dos íons agressivos e água até o substrato metálico. Nanopartículas de celulose apresentam elevada cristalinidade e razão de aspecto, excelentes propriedades mecânicas e são proveniente de fonte renovável. Por outro lado, a polianilina (PAni) vem sendo utilizada em revestimentos devido a elevação do potencial de corrosão dos aços devido o seu comportamento redox que proporciona a formação de uma camada de óxidos estável no substrato metálico. A aderência do revestimento polimérico é fundamental para que este possa atuar como revestimento protetor contra a corrosão. Com isso, um pré-tratamento superficial a base de ácido hexafluorzircônico e a utilização de organosilanos na resina epóxi, podem ser utilizados melhorando as propriedades de proteção contra a corrosão e de aderência. O objetivo deste estudo consistiu na obtenção de nanowhiskers de celulose (CNW) por moagem ultrafina através da celulose microcristalina (MCC) para posterior utilização em revestimento polimérico a base de resina epóxi. A CNW foi utilizada funcionalizada ou não com PAni SE (polianilina na forma condutora – sal de esmeraldina) em comparação a MCC nas mesmas condições. Foi avaliada a incorporação de silano aminopropiltrietoxisilano (APS) na resina epóxi e a utilização de uma camada de conversão de zircônia (Zr) aplicada ao substrato metálico. Os revestimentos poliméricos foram avaliados quanto a propriedades mecânicas e à proteção contra a corrosão. As imagens da microscopia de transmissão (TEM) mostram que é possível a obtenção da CNW por meio do processo de moagem, apresentando melhor estabilidade térmica em comparação a MCC. Os revestimentos poliméricos utilizando o silano APS e a camada de conversão de Zr apresentaram as melhores propriedades físicas e mecânicas. A interação entre a carga de reforço, a resina epóxi e a superfície metálica é um fator determinante na eficiência do revestimento polimérico, pois de acordo com a análise de migração subcutânea, a superfície do aço carbono, após 1000 h de exposição, não apresentou corrosão superficial. Com relação à proteção contra a corrosão, quando incorporado a CNW funcionalizada com PAni SE ao revestimento epóxi com APS e a camada de Zr, este apresentou os melhores resultados como constatado nas análises de névoa salina e espectroscopia de impedância eletroquímica (EIS). / Polymeric coatings can act as a physical barrier between the aggressive ions and the metal substrate. However, prolonged exposure can cause damage to the polymer coating and conduct to a continuous reduction in the barrier effect and result in the loss of protection against corrosion. The use of nanomaterials may act by increasing the barrier effect and providing an increased diffusion path of aggressive ions and water to the metal substrate. Cellulose nanoparticles have high crystallinity and aspect ratio, excellent mechanical properties and are derived from renewable sources. On the other hand polyaniline (PAni) has been used in coatings due to the increase of the corrosion potential of the steel due to redox behavior that results in the formation of a stable oxide layer on the metallic substrate. The adhesion of the polymeric coating is essential so that it can act as a protective coating against corrosion. With this, a superficial pre-treatment based on hexafluorzircônico acid and the use of organosilanes in the epoxy resin, can be used to improve the protection against corrosion properties and adhesion. The objective of this study was to obtain cellulose nanowhiskers (CNW) for ultrafine grinding through microcrystalline cellulose (MCC) for subsequent use in the polymer coating based on epoxy resin. The CNW was used functionalized or not with PAni SE (polyaniline in the conductive form - emeraldine salt) compared with MCC under the same conditions. The incorporation of silane aminopropyltriethoxysilane (APS) was evaluated in the epoxy resin and the use of a zirconia conversion layer (Zr) applied to the metal substrate. The polymeric coatings were evaluated for mechanical properties and corrosion protection. Transmission microscopy (TEM) show that obtaining the CNW through the ultrafine grinding process is possible, resulting in better thermal stability compared with MCC. Polymeric coatings using APS silane and Zr conversion coating had the best physical and mechanical properties. The interaction between the reinforcing filler, the epoxy resin and the metal surface is a determining factor in the efficiency of the polymeric coating, because according to the subcutaneous migration analysis, carbon steel surface after 1000 h of exposure, showed no corrosion superficial. With regard to protection against corrosion, when incorporated CNW functionalized with PAni SE to epoxy coating with APS and the Zr layer, showed the best results as found in salt spray tests and electrochemical impedance spectroscopy (EIS).