Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-05-30T23:20:44Z No. of bitstreams: 1 JulianaRicardoDeSouza_TESE.pdf: 14513350 bytes, checksum: 9e7d4d9cfe9132db18a4d5ee9940a771 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-06-01T23:23:24Z (GMT) No. of bitstreams: 1 JulianaRicardoDeSouza_TESE.pdf: 14513350 bytes, checksum: 9e7d4d9cfe9132db18a4d5ee9940a771 (MD5) / Made available in DSpace on 2016-06-01T23:23:24Z (GMT). No. of bitstreams: 1 JulianaRicardoDeSouza_TESE.pdf: 14513350 bytes, checksum: 9e7d4d9cfe9132db18a4d5ee9940a771 (MD5) Previous issue date: 2015-06-05 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / A estocagem de rejeitos de scheelita a ?c?u aberto? resultante da explora??o da mina Breju? da regi?o de Currais Novos, Rio Grande do Norte, Brasil, tem gerado, no per?odo 1960-2015, um forte passivo ambiental. O pol?mero politetrafluoretileno (PTFE) majora em sistemas de deslizamento e reduz significativamente custos de manuten??o, devido ?s suas excelentes propriedades mec?nicas, tais como baixo coeficiente de atrito (0,01< m <0,10) e limite de escoamento da ordem de 10 MPa. No entanto, apresenta elevadas taxas de desgaste (10-13 m2/N) e por despertar o interesse cient?fico e tecnol?gico nas ind?strias petroqu?mica e aeroespacial na forma de lubrificantes s?lidos, objetivou-se desenvolver comp?sitos polim?ricos com matriz de PTFE utilizando-se o rejeito de scheelita como carga, viabilizando tamb?m processos de remedia??o ambiental. O Rejeito de Scheelita foi caracterizado na condi??o como adquirido, atrav?s de an?lises de DRX, FRX, MEV, EDS, granulometria por Peneiramento e a Laser, registrando-se tra?os de tungst?nio e metais estrat?gicos igualmente importantes. O PTFE foi analisado por TGA, DSC, MEV, DRX, FRX. Para o desenvolvimento dos comp?sitos misturou-se mecanicamente os p?s de PTFE e Rejeito de Scheelita, devidamente preparados e pesados. Para moldagem por compress?o ? quente projetou-se um molde cil?ndrico de a?o acoplado a uma resist?ncia inseridos numa prensa hidr?ulica. Avaliaram-se o desempenho tribol?gico dos comp?sitos obtidos a partir de Rugosidade, Dureza, Molhabilidade, Absor??o ao impacto, Esclerometria, Pino Disco e Analise Morfol?gica. Os resultados indicam que a varia??o no teor de rejeito de scheelita influ?ncia nos resultados de rugosidade, dureza e absor??o ao impacto. Comp?sitos molhados com ?gua salina e destilada caracterizaram-se como hidrof?bicos, enquanto que os molhados com ?leo paraf?nico e naft?nico como oleof?licos. Correlacionando os resultados dos ensaios tribol?gicos e custos constatou-se que a composi??o de 20% de Rejeito de Scheelita apresentou a melhor planicidade, baixo consumo de energia de deforma??o espec?ficica (<0,30 J/mm3), a menor perda m?ssica (8x10-3g) e afundamento da pista (<0,4 ?m/km). / The storage scheelite tailings in the open air as a result of Breju? mine exploration, located near Currais Novos, Rio Grande do Norte, Brazil, between 1960 and 2015, a strong environmental passive. The polymer polytetrafluoroethylene (PTFE) outstands in sliding systems and significantly reduces maintenance costs, due to its excellent mechanical properties, such as low friction coefficient (0,01< ? <0,10) and yield limit to the order of 10MPa. However, it has high wear rates (10-13 m2/N) and for arousing scientific and technological interests at petrochemical and aerospace industry, in the form of solid lubricants, the target was to develop polymeric composites with a PTFE matrix using tailings of scheelite as charge, enabling also environmental remediation processes. The tailing of Sheelite was characterized in acquired conditions, through XRD, XRF, SEM, EDS, granulometry by screening and by laser, recording traces of tungsten and strategic metals equally important. The PTFE was analyzed by TG, DSC, SEM, XRD, XRF. To the composites development, powders of PTFE and tailings of sheelite were mechanically mixed, previously prepared and weighed. To hot compression molding, a designed cylindrical steel mould was coupled with a resistor and placed in a hydraulic press. The composite?s tribological performance was evaluated from roughness, hardness, wettability, impact absorption, sclerometry, pin on disc, and morphological analysis. The results show that the variation in the tailing of scheelite concentration influences the results of roughness, hardness and impact absorption. Wet composites with saline and distilled water were characterized as hydrophobic, and the ones wet with paraffenic and naphtenic oil, they acted oleophilic. Correlating the results of tribological tests and costs, it was found that the composition of 20% mineral filler showed better planeness, low specific deformation energy consumption (<0,30J/mm?), the lowest mass loss (8x10-4g) and trail shipwreck (<0,4?m/km).

Made available in DSpace on 2014-12-17T14:58:10Z (GMT). No. of bitstreams: 1 YgorAAF.pdf: 1834910 bytes, checksum: ddd6f585ec4f1145f34bbec8197b2e39 (MD5) Previous issue date: 2006-05-19 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / In this work, were produced ceramic matrix composites based in SiCxOy e Al2O3 reinforced with NbC, by hydrosilylation reaction between D4Vi and poly(methylhydrosiloxane) mixtured with Al2O3 as inert filler, Nb and Al as reactive filler. After the mixture and compactation at 80?C (warm pressing), the samples were pyrolised at 1200 and 1400?C and infiltred with ICZ and LZSA respectively, and thermically, physical and structurally characterized by X-ray diffraction, density and porosity, flexural mechanical strength and fracture surface by scanning electron microscopy. The yield ceramic obtained after pyrolysis for studied composition at 1200?C was 95%. The obtained phases had been identified as being Al3Nb, NbSi2 and NbC. The composite material presented apparent porosity varying of 15 up to 32% and mechanical flexural strenght of 32 up to 37,5MPa. After the fracture surface analysis, were observed a phases homogeneous dispersion, with some domains of amorphous and crystalline aspect. The samples that were submitted the infiltration cycle presented a layer next the surface with reduced pores number in relation to the total volume / Neste trabalho foram produzidos comp?sitos de matriz cer?mica baseados em SiCxOy e Al2O3 refor?ados com NbC, a partir da rea??o de hidrossila??o entre os olig?meros D4Vi (1,3,5,7 tetrametil 1,3,5,7 tetravinilciclotetrasiloxano) e D1107 - Poli(metilhidrogeniosiloxano), misturados com Al2O3 como carga inerte, Nb e Al como aditivos reativos. Ap?s a mistura e compacta??o em 80 ?C (warm pressing), as amostras foram pirolisadas ? 1200 e 1400?C e infiltradas com ICZ e LZSA respectivamente, e caracterizadas t?rmica, f?sica e estruturalmente atrav?s de an?lises t?rmicas (TG e DTA), identifica??o de fases cristalinas por difratometria de raios-x, densidade e porosidade, resist?ncia mec?nica ? flex?o e superf?cie de fratura por microscopia eletr?nica de varredura. O Rendimento cer?mico obtido para a composi??o estudada ? 1200?C foi de 95%. As fases formadas ap?s a pir?lise foram identificadas como sendo Al3Nb, NbSi2 e NbC os comp?sitos apresentaram porosidade aparente variando de 15 a 32 por cento e resist?ncia mec?nica a flex?o, de 32 a 37,5MPa. Ap?s a an?lise da superf?cie de fratura observou-se uma dispers?o homog?nea de fases, com algumas regi?es de aspecto amorfo e cristalino. As amostras que foram submetidas a ciclo de infiltra??o apresentaram uma camada pr?xima a superf?cie com reduzido n?mero de poros em rela??o ao volume total

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-02-20T22:32:00Z No. of bitstreams: 1 GustavoSantosDeLucenaLira_DISSERT.pdf: 3769609 bytes, checksum: 905dd4b5e1b62301b226e882500c5d84 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-02-23T22:29:34Z (GMT) No. of bitstreams: 1 GustavoSantosDeLucenaLira_DISSERT.pdf: 3769609 bytes, checksum: 905dd4b5e1b62301b226e882500c5d84 (MD5) / Made available in DSpace on 2017-02-23T22:29:34Z (GMT). No. of bitstreams: 1 GustavoSantosDeLucenaLira_DISSERT.pdf: 3769609 bytes, checksum: 905dd4b5e1b62301b226e882500c5d84 (MD5) Previous issue date: 2016-09-29 / A participa??o das cargas naturais nos comp?sitos tem possibilitado a melhoria de sua estrutura mec?nica, bem como, a economia de aplica??o de cargas sint?ticas, as quais al?m de possu?rem alto valor de mercado, envolvem processos de fabrica??o e reciclagem nocivos a sa?de do homem. Nesse sentido, foram fabricados comp?sitos polim?ricos ? base de polipropileno, como matriz, e o particulado do endocarpo do Cocos Nuc?fera Linn (10 e 20 %wt), na fun??o de carga. Com o objetivo de obter uma eficiente intera??o na interface do particulado com a matriz e uma distribui??o uniforme do particulado no pol?mero, foi utilizada uma faixa granulom?trica do particulado de 0,5 a 0,263 mm. J? para fabrica??o dos corpos-de-prova, o material foi processado por extrus?o, com extrusora dupla rosca, e, em seguida, a inje??o, variando a temperatura de processamento em at? 200 ?C, no intuito de atingir um valor acima da temperatura de transi??o v?trea do res?duo lignocelul?sico, a fim de que a resina natural (lignina) auxilie a ades?o com a matriz. Para a caracteriza??o do particulado do endocarpo do coco utilizou-se a an?lise termogravim?trica e a microscopia eletr?nica de varredura, enquanto para os comp?sitos foram utilizados os ensaios de densidade volum?trica, de tra??o, de flex?o e a microscopia eletr?nica de varredura. Dessa forma, apesar da presen?a da carga ter gerado diminui??o da ductilidade e resist?ncia mec?nica, concluiu-se que a adi??o do particulado na matriz de Polipropileno possibilitou aumento no m?dulo de elasticidade ? tra??o de 4,0% para o comp?sito com 10,0 %wt e de 11% para o de 20%wt. No ensaio de flex?o, a carga possibilitou aumento do m?dulo de elasticidade em 6,4% para comp?sito com 10%wt e em 8,8% para o de 20%wt em rela??o ao polipropileno puro. Para a an?lise termogravim?trica, foram obtidos os patamares de temperaturas de degrada??o dos res?duos lignoc?lulosicos, sendo: a degrada??o da hemicelulose entre 210,80 e 255,32 ?C, a da celulose entre 255,32 e 328,31 e, por fim, a da lignina entre 328,31 e 495,82 ?C. Para os ensaios de densidade, observou-se que os comp?sitos possuem valores de densidades pr?ximos ao polipropileno puro, permitindo a aplica??o destes em estruturas leves. / The use of natural residues as a reinforcement in the production of plastic composites has enabled the improvement of its mechanical structure and saved the utilization of synthetic reinforcement that has manufacturing processes and recycling harmful to human health. In this study were fabricated polypropylene composites with 10 and 20 %wt of coconut (Cocos Nuc?fera Linn) shell load. To the optimization of the interfacial bond between particulate and polymer matrix were utilized a granulometric range of 0,5 a 0,263 mm and fabricated using temperature maximum of 200 ?C, above the glass transition temperature of lignocellulosic residue, by extrusion and injection moulding. The properties of particulate, composites and polymers were investigated by density, tensile and flexural testing, thermogravimetry and Scanning electron microscope. The polymer had its ductility and mechanical resistance decreased with particulate addition, thus, its modulus of elasticity increased 4,0% to 10%wt and 11,0% to 20%wt in relation to polypropylene. The flexural modulus of elasticity increased 6,4% to 10%wt and 8,8 to 20%wt in relation to polypropylene. The thermogravimery demonstrated the degradation temperatures of lignocellulosic residues (hemicellulose between 210,80 and 255,32 ?C, cellulose between 255,32 and 328,31, lignin between 328,31 e 495,82 ?C. For density testing, it was observed that the composites have a density values close to polypropylene, allowing the application in lightweight structures.

Submitted by Caroline Xavier (caroline.xavier@pucrs.br) on 2017-10-05T11:34:54Z No. of bitstreams: 1 TES_LUIS_FERNANDO_MELEGARI_COMPLETO.pdf: 6221745 bytes, checksum: 6fea166b18494e244d24dddc530d9abc (MD5) / Approved for entry into archive by Caroline Xavier (caroline.xavier@pucrs.br) on 2017-10-05T11:35:04Z (GMT) No. of bitstreams: 1 TES_LUIS_FERNANDO_MELEGARI_COMPLETO.pdf: 6221745 bytes, checksum: 6fea166b18494e244d24dddc530d9abc (MD5) / Made available in DSpace on 2017-10-05T11:35:13Z (GMT). No. of bitstreams: 1 TES_LUIS_FERNANDO_MELEGARI_COMPLETO.pdf: 6221745 bytes, checksum: 6fea166b18494e244d24dddc530d9abc (MD5) Previous issue date: 2017-07-25 / The use of polymeric materials to substitute an array of others like metal has its development level increased when new compounds are applied as well as new formation technologies. An approach of the main factors lately used for its assessment was necessary to prove the polymeric material?s behavior when applied in gears for strength transmission. The presented analysis were based on practical experiences and through methods of finite elements, using diverse composites and addition loads to form the tested polymers in controlled conditions for torque, temperature and rotation, making use of the device development of movement and specific control. The polymeric gears behave in different ways according to specific conditions of temperature, rotation and torque request, presenting a variety of results due to the polymers used in its formation. The geometry of the project and the profile construction of the conical gears? tooth had direct influence under the performance, being possible to reduce the tensions in the tooth?s root. The injected pieces supply a body of proves to a mechanic dynamic thermal analysis, these results present discrepancy among the base materials regarding Tm. The replacement of metallic materials for polymeric materials must consider the characteristics of each application. / A utiliza??o de materiais polim?ricos em substitui??o a diversos outros como o metal tem seu n?vel de desenvolvimento aumentado na aplica??o de novos compostos bem como novas tecnologias de forma??o. Uma abordagem dos principais fatores ultimamente utilizados para sua avalia??o fez-se necess?ria para a comprova??o do comportamento dos materiais polim?ricos na aplica??o em engrenagens de transmiss?o de for?a. As an?lises apresentadas foram baseadas em experimenta??es pr?ticas e atrav?s de m?todos de elementos finitos, utilizando diversos comp?sitos e cargas de adi??o para forma??o dos pol?meros testados em condi??es controladas de torque, temperatura e rota??o, utilizando-se de desenvolvimento de dispositivo de movimenta??o e controle espec?fico. As engrenagens polim?ricas comportaram-se de diferentes formas em condi??es espec?ficas de temperatura, rota??o e solicita??o de torque, apresentando resultados variados em fun??o dos pol?meros utilizados em sua forma??o. A geometria de projeto e constru??o do perfil do dente das engrenagens c?nicas teve influ?ncia direta em rela??o ao desempenho, sendo poss?vel a redu??o das tens?es na raiz do dente. As pe?as injetadas forneceram corpos de prova para an?lises t?rmico din?mico mec?nicas, os resultados destas apresentaram discrep?ncia entre os materiais base no que se refere a Tm. A substitui??o de materais met?licos por materiais polim?ricos deve levar em considera??o as caracter?sticas para cada aplica??o.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2018-01-15T21:40:49Z No. of bitstreams: 1 VirginiaBezerraOliveiraCampos_DISSERT.pdf: 3793113 bytes, checksum: 4435d7d3c46fc8d73615a9b23cd0e5f4 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2018-01-17T15:55:28Z (GMT) No. of bitstreams: 1 VirginiaBezerraOliveiraCampos_DISSERT.pdf: 3793113 bytes, checksum: 4435d7d3c46fc8d73615a9b23cd0e5f4 (MD5) / Made available in DSpace on 2018-01-17T15:55:28Z (GMT). No. of bitstreams: 1 VirginiaBezerraOliveiraCampos_DISSERT.pdf: 3793113 bytes, checksum: 4435d7d3c46fc8d73615a9b23cd0e5f4 (MD5) Previous issue date: 2017-08-10 / A constante busca de materiais mais eficientes e com alto desempenho mec?nico, contribue efetivamente para a crescente demanda na utiliza??o de comp?sitos h?bridos. O processo de hibridiza??o pode propiciar melhoria significativa na combina??o global de propriedades, possibilitando assim aplica??es espec?ficas em elementos estruturais que requerem excel?ncia em suas propriedades mec?nicas e baixa massa espec?fica. Atrelado ? gradativa utiliza??o destes materiais, estudos que incidem nas previs?es de falha e, consequentemente, an?lises das cargas m?ximas que estes materiais podem suportar tornam-se essenciais para garantia da confiabilidade quanto a sua aplica??o. Neste sentido, a presente pesquisa buscou analisar o comportamento mec?nico de uma l?mina constitu?da ? base de tecido h?brido bidirecional (vidro/carbono) e resina ep?xi ?ster-vin?lica. Bem como, avaliar a representatividade de crit?rios de falhas desenvolvidos para comp?sitos unidirecionais quando aplicados em comp?sito h?brido de natureza bidirecional. A l?mina estudada foi caracterizada mecanicamente com base nos resultados obtidos pelos ensaios de tra??o e cisalhamento realizados em amostras com fibras de carbono orientadas a 0?, 30?, 45?, 60? e 90?. Observou-se a partir destes ensaios que materiais com fibras em ?ngulos fora do eixo (off-axis) de aplica??o de carga apresentam resist?ncia menor, embora apresentem maiores alongamentos, quando comparados a amostras com fibras alinhadas na dire??o principal do carregamento. Os dados experimentais referentes ?s propriedades cisalhantes, normatizados pela ASTM D3518M-13 (ensaio de cisalhamento por tra??o ?45?) e ASTM D5379-12 (ensaio de Iosipescu), apresentaram diferen?as significativas para a resist?ncia ao cisalhamento e similaridade nos valores do m?dulo de cisalhamento. O ensaio de tra??o ?45?, conforme an?lise macromec?nica, mostrou-se como o mais adequado para comp?sito com caracter?sticas similares ao analisado. Ao inserir os dados dos ensaios nas equa??es te?ricas que definem os crit?rios de falhas da M?xima Tens?o, Tsai-Hill, Tsai-Wu e Hashin e, analis?-los estatisticamente, contatou-se que estas teorias de falhas descrevem satisfatoriamente o comportamento experimental da l?mina, e, portanto, podem ser utilizados para predizer a resist?ncia mec?nica em comp?sitos como o avaliado, embora se tenha observado ?ndices de representatividade maiores quando se utiliza o ensaio de cisalhamento por tra??o ?45?. / The constant search for more efficient materials and with high mechanical performance, contributes effectively to the growing demand in the use of hybrid composites. The hybridization process can provide significant improvement in the overall combination of properties, thus enabling specific applications in structural elements that require excellence in their mechanical properties and low specific mass. Coupled with the gradual use of these materials, studies that focus on fault predictions and, consequently, analyzes of the maximum loads that these materials can withstand become essential to guarantee the reliability of their application. In this sense, the present research sought to analyze the mechanical behavior of laminae composed of two-way hybrid fabric (glass/carbon) and epoxy resin vinyl ester. As well as evaluating the representativeness of failure criteria developed for unidirectional composites when applied in hybrid composites of a bidirectional nature. The laminas studied were mechanically characterized based on the results obtained by tensile and shear tests performed on samples with carbon fibers orientated at 0?, 30?, 45?, 60? and 90?. It was observed from these tests that materials with fibers at off-axis loading angles exhibit lower strength, although they exhibit greater elongations when compared to samples with fibers aligned in the main direction of loading. Experimental data on shear properties, standardized by ASTM D3518M-13 (tensile shear test ?45?) and ASTM D5379-12 (Iosipescu's test), showed significant differences for shear strength and similarity in the modulus values of Shear. The tensile test ? 45?, according to macromechanical analysis, proved to be the most suitable for composite with characteristics similar to the one analyzed. By inserting test data into the theoretical equations defining Tsai-Hill, Tsai-Wu, and Hashin fault criteria, and statistically analyzing them, it was found that these fault theories satisfactorily describe the experimental behavior of the blade , and therefore can be used to predict mechanical strength in composites as evaluated, although higher representativity indices were observed when using the ? 45? traction shear test.

Made available in DSpace on 2014-12-17T14:07:00Z (GMT). No. of bitstreams: 1 AntonioCSC_DISSERT.pdf: 3611638 bytes, checksum: 66d2009e96e503fa1be4ca56924e34a1 (MD5) Previous issue date: 2011-03-14 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The clay mineral attapulgite is a group of hormitas, which has its structures formed by microchannels, which give superior technological properties classified the industrial clays, clays of this group has a very versatile range of applications, ranging from the drilling fluid for wells oil has applications in the pharmaceutical industry. Such properties can be improved by activating acid and / or thermal activation. The attapulgite when activated can improve by up to 5-8 times some of its properties. The clay was characterized by X-ray diffraction, fluorescence, thermogravimetric analysis, differential thermal analysis, scanning electron microscopy and transmission electron microscopy before and after chemical activation. It can be seen through the results the efficiency of chemical treatment, which modified the clay without damaging its structure, as well as production of polymer matrix composites with particles dispersed atapugita / A atapulgita ? um argilomineral do grupo das hormitas, que tem suas estruturas formadas por microcanais, que lhe conferem propriedades tecnol?gicas superiores a argilas classificadas industriais, esse grupo de argilas tem um leque de aplica??es muito vers?til, que vai de fluido de perfura??o para po?os de petr?leo at? aplica??es na ind?stria farmac?utica. Tais propriedades podem ser melhoradas por ativa??o acida e/ou ativa??o t?rmica. A atapulgita quando ativada pode melhorar em at? de 5 a 8 vezes algumas de suas propriedades. A argila foi caracterizada por difra??o de raios X, fluoresc?ncia, an?lise termogravim?trica, an?lise t?rmica diferencial, microscopia eletr?nica de varredura e microscopia eletr?nica de transmiss?o antes e depois da ativa??o qu?mica. ? poss?vel observar, atrav?s dos resultados a efici?ncia do tratamento qu?mico, que modificou a argila sem danificar sua estrutura, assim como produ??o de composito de matriz polim?rica com part?culas dispersas de atapugita

Made available in DSpace on 2014-12-17T14:07:02Z (GMT). No. of bitstreams: 1 FabioSCPpdf.pdf: 1533458 bytes, checksum: 0df903e6bea6c66d762b8b1bbe3c6937 (MD5) Previous issue date: 2009-11-30 / Due to the occurrence of diseases in the use of structural reinforcements in composites, with presentation of concrete blanket detachment, has been identified the need to evaluate the performance of concrete reinforced with glass fiber. This study aims to evaluate these concretes by means of testing methodologies, using concrete with low resistance with structural reinforcement for confinement by preimpregnated glass fiber and traditional fiberglass blanket. The first stage of work was the development of methodologies for analysis, opting for four types, such as the acoustic survey, strength to compressive, the pull-off and ultrasound. Next, tests were carried out using the four selected methodologies in 30 of proof-of-specimens by 5x10 cm, 15 were reinforced with the traditional fiberglass blanket with 5specimens exposed to test a marine environment of marine coastline of Natal-RN and 15 were reinforced with a pre-impregnated glass fiber blanket, as well as 5specimens exposed to a test environment of the marine coastline of Natal-RN. After conducting the acoustic survey, it has been verified a lack of delaminating and air bubbles in the samples, confirming the absence of gross shortcomings in the implementation of the ribs both the traditional fiberglass blanket and in the preimpregnated fiber glass blanket. After carrying out methods of pull-off and compressive strengthening test it was observed that the reinforced proof-bodies with pre-impregnated glass blanket showed maximum stresses higher than the traditional fiberglass blanket; consequently a greater grip with the formation of a smaller area of . fracture, unlike traditional glass mat, which showed lower maximum stresses, with a greater area of fracture. It was also found that the traditional fiberglass blanket presented detachment of blanket-concrete interface, unlike the pre-impregnated fiberglass blanket, which showed a better grip on the blanket-concrete interface. In the trial of ultrasound there was no presence of cracks in the blanket-concrete interface, yielding to both blankets good compactness of the concrete. At the end of this work, they were developed and proposed two methods of testing for evaluation of reinforced concrete structures with composites, for standardization, the acoustic survey and pull-off / Em virtude da ocorr?ncia de patologias na utiliza??o de refor?os estruturais com comp?sitos, com apresenta??o de descolamento da manta do concreto, foi identificada a necessidade de se avaliar o desempenho dos concretos refor?ados com a fibra de vidro. Sendo o objetivo principal deste trabalho, avaliar estes concretos, atrav?s de metodologias de ensaios, utilizando concretos com resist?ncias baixas com refor?o estrutural por confinamento por fibra de vidro pr?impregnada e por manta de fibra de vidro tradicional. A primeira etapa do trabalho consistiu na elabora??o das metodologias de an?lise, optando-se por quatro tipos, a sondagem ac?stica, resist?ncia ? compress?o,o pull-off e o ultra-som. Em seguida, foram realizados os ensaios utilizando as quatro metodologias escolhidas em 30 corpos-de-prova de 5x10 cm, sendo 15 refor?ados com a manta de fibra de vidro tradicional, com 5 corpos-de-prova expostos a um ambiente marinho da orla mar?tima de Natal-RN e sendo 15 refor?ados com a manta de fibra de vidro pr?impregnada, tamb?m com 5 corpos-de-prova expostos a um ambiente marinho da orla mar?tima de Natal-RN. Ap?s a realiza??o dos ensaios de sondagem ac?stica, verificou-se a inexist?ncia de delamina??es e bolhas de ar nas amostras analisadas, comprovando a inexist?ncia de falhas grosseiras na aplica??o dos refor?os tanto na manta de fibra de vidro tradicional, como na da manta de fibra de vidro pr?impregnada. Depois de executadas as metodologias de ensaios de resist?ncia ? compress?o e pull-off, observou-se que os corpos-de-prova refor?ados com a manta de vidro pr?-impregnada apresentaram tens?es m?ximas superiores ?s obtidas com a manta de fibra de vidro tradicional, consequentemente uma ader?ncia maior, com a forma??o de uma menor ?rea de fratura, ao contr?rio da manta de vi dro tradicional, que apresentou tens?es m?ximas inferiores, com uma maior ?rea de fratura. Verificou-se ainda que a manta de fibra de vidro tradicional apresentou descolamento da interface manta/concreto, ao contr?rio da manta de fibra de vidro pr?-impregnada, que apresentou uma maior ader?ncia na interface manta/concreto. No ensaio de ultra-som n?o se observou presen?a de fissuras na interface manta/concreto, obtendo-se para ambas as mantas, boas compacidades do concreto. Ao final do trabalho foram elaboradas e propostas duas metodologias de ensaios para avalia??o das estruturas de concreto armado refor?adas com comp?sitos, para normaliza??o, a sondagem ac?stica e o pull-off

Made available in DSpace on 2014-12-17T14:07:24Z (GMT). No. of bitstreams: 1 MarcusAlexandreD.pdf: 2205651 bytes, checksum: 56cca2e578c0f1071a36ad849c8f80ca (MD5) Previous issue date: 2007-10-01 / Ceramic composites produced with polymerics precursors have been studied for many years, due to the facility of obtaining a complex shape, at low temperature and reduces cost. The main objective of this work is to study the process of sintering of composites of ceramic base consisting of Al2O3 and silicates, reinforced for NbC, through the technique of processing AFCOP, as well as the influence of the addition of LZSA, ICZ and Al as materials infiltration in the physical and mechanical properties of the ceramic composite. Were produced ceramic matrix composites based SiCxOy e Al2O3 reinforced with NbC, by hidrosilylation reaction between D4Vi and D1107 mixtured with Al2O3 as inert filler, Nb and Al as reactive filler. The specimens produced were pyrolised at 1200, 1250 and 1400?C and infiltred with Al, ICZ and LZSA, respectively. Density, porosity, flexural mechanical strength and fracture surface by scanning electron microscopy were evaluated. The microstructure of the composites was investigated by X-ray diffraction to identify the presence of crystalline phases. The composites presented apparent porosity varying of 31 up to 49% and mechanical flexural strength of 14 up to 34 MPa. The infiltration process improviment of the densification and reduction of the porosity, as well as increased the values of mechanical flexural strength. The obtained phases had been identified as being Al3Nb, NbSi2, Nb5S3, Nb3Si and NbC. The samples that were submitted the infiltration process presented a layer next surface with reduced pores number in relation to the total volume / Os comp?sitos cer?micos produzidos atrav?s de precursores polim?ricos v?m sendo estudados h? v?rios anos, tendo em vista a facilidade de moldagem em formas complexas, menores temperaturas de sinteriza??o e custo reduzido. O principal objetivo deste trabalho ? estudar o processo de sinteriza??o de comp?sitos de base cer?mica constitu?da de alumina e silicatos, refor?ados por carbetos de ni?bio, atrav?s da t?cnica de processamento AFCOP, bem como a influ?ncia da adi??o de LZSA, ICZ, e Al como materiais infiltrantes nas propriedades f?sicas e mec?nicas do comp?sito cer?mico. Foram produzidos comp?sitos de matriz cer?mica baseados em SiCxOy e Al2O3 refor?ados com carbeto de ni?bio, a partir da rea??o de hidrossila??o entre os olig?meros D4Vi (1,3,5,7 tetrametil 1,3,5,7 tetravinilciclotetrasiloxano) e D1107 Poli (metilhidrogeniosiloxano), misturados com alumina como carga inerte, ni?bio e alum?nio como aditivos reativos. As amostras produzidas foram pirolisadas a 1200?C, 1250?C e 1400?C e infiltradas com Al, ICZ e LZSA, respectivamente. Foram realizados ensaios de densidade, porosidade, resist?ncia mec?nica ? flex?o e an?lises da superf?cie de fratura por microscopia eletr?nica de varredura. A microestrutura dos comp?sitos foi investigada pela an?lise de difra??o de raios-x para identifica??o das fases cristalinas presentes. Os comp?sitos apresentaram porosidade aparente variando de 31 a 49 por cento e resist?ncia mec?nica ? flex?o de 14 a 34 MPa. Os resultados mostraram que o processo de infiltra??o promoveu uma melhoria na densifica??o e redu??o da porosidade, bem como um incremento nos valores de resist?ncia mec?nica do comp?sito. As fases formadas ap?s a pir?lise foram identificadas como sendo Al3Nb, NbSi2, Nb5Si3, Nb3Si e NbC. As amostras que foram submetidas ao processo de infiltra??o apresentaram uma camada superficial com reduzido n?mero de poros em rela??o ao volume total

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-02-01T21:32:18Z No. of bitstreams: 1 NatanaeyfleRandembergGomesDosSantos_TESE.pdf: 3542697 bytes, checksum: 97843b739f0b1a5bdcb53b7f88ac2d7a (MD5) / Approved for entry into archive by Elisangela Moura (lilaalves@gmail.com) on 2016-02-16T20:41:39Z (GMT) No. of bitstreams: 1 NatanaeyfleRandembergGomesDosSantos_TESE.pdf: 3542697 bytes, checksum: 97843b739f0b1a5bdcb53b7f88ac2d7a (MD5) / Made available in DSpace on 2016-02-16T20:41:39Z (GMT). No. of bitstreams: 1 NatanaeyfleRandembergGomesDosSantos_TESE.pdf: 3542697 bytes, checksum: 97843b739f0b1a5bdcb53b7f88ac2d7a (MD5) Previous issue date: 2015-02-05 / A utiliza??o de materiais comp?sitos para a constru??o civil tem sido tema de in?meros trabalhos cient?ficos no Brasil e no mundo. Um dos fatores que motivam essa busca ? o d?ficit habitacional que os pa?ses principalmente do terceiro mundo enfrentam. No Brasil esse d?ficit alcan?a mais de 6,5 milh?es de moradias, em torno de 12% dos domic?lios do pa?s. Esse trabalho apresenta um comp?sito que foi obtido a partir de res?duos gerados nos processos de obten??o de placas de granito e m?rmore, cimento, gesso, areia, EPS triturado e ?gua. Esses res?duos causam grandes danos ao meio ambiente e s?o jogados em aterros em grandes quantidades. O ineditismo do trabalho est? no estudo combinado t?rmico, mec?nico e ac?stica do comp?sito obtido, em situa??o real, de c?modos que fazem parte de uma habita??o experimental. Foram confeccionados diversos blocos a partir de composi??es variadas e foram efetuados testes preliminares de resist?ncia mec?nica e t?rmica, escolhendo-se a propor??o mais apropriada. Ser?o apresentados os processos de fabrica??o e montagem dos blocos produzidos, em n?mero de 500, para a fabrica??o de uma resid?ncia experimental. Estudou-se qual o tipo de bloco e de res?duo, m?rmore ou granito, apresentou-se mais vi?vel para o fim proposto. A resist?ncia mec?nica dos blocos produzidos esteve acima de 3,0 MPa. A resist?ncia t?rmica dos blocos foi comprovada pela diferen?a m?xima entre as paredes interna e externa dos c?modos edificados em torno 8,0 ?C. A absor??o ac?stica para o c?modo mais eficiente ficou em torno 31. Demonstrou-se a viabilidade de utiliza??o dos blocos fabricados com o material comp?sito proposto para a constru??o civil. / The use of composite materials for the construction industry has been the subject of numerous scientific papers in Brazil and in the world. One of the factors that motivate this quest is the housing deficit that countries especially the third world face. In Brazil this deficit reaches more than 6.5 million homes, around 12% of all US households . This paper presents a composite that was obtained from waste generated in processes for the production of granite and marble slabs, cement, gypsum, sand, crushed EPS and water. These wastes cause great damage to the environment and are thrown into landfi lls in bulk. The novelty of the work is in the combined study thermal, mechanical and acoustic composite obtained in real situation of rooms that are part of an experimental housing. Many blocks were made from cement compositions, plaster, foam, sand, marb le and / or granite, preliminary tests of mechanical and thermal resistance were made by choosing the most appropriate proportion. Will be given the manufacturing processes and assembly units 500 units 10 x 80 x 28 cm produced for the construction of an ex perimental home. We studied what kind of block and residue, marble or granite, made it more feasible for the intended purpose. The mechanical strength of the produced blocks were above 3.0 MPa. The thermal resistance of the blocks was confirmed by the maxi mum temperature difference between the inner and outer walls of rooms built around 8.0 ? C. The sound absorption for optimal room was around 31%. Demonstrated the feasibility of using the blocks manufactured with composite material proposed for construction.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-05-10T21:07:59Z No. of bitstreams: 1 JoseRenatoLimaCamara_DISSERT.pdf: 3552276 bytes, checksum: b25cc5d6b64a03d05ff895c1737a2060 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-05-12T23:11:02Z (GMT) No. of bitstreams: 1 JoseRenatoLimaCamara_DISSERT.pdf: 3552276 bytes, checksum: b25cc5d6b64a03d05ff895c1737a2060 (MD5) / Made available in DSpace on 2016-05-12T23:11:02Z (GMT). No. of bitstreams: 1 JoseRenatoLimaCamara_DISSERT.pdf: 3552276 bytes, checksum: b25cc5d6b64a03d05ff895c1737a2060 (MD5) Previous issue date: 2015-07-31 / Este trabalho consiste no desenvolvimento de um comp?sito a base de rejeito de telha epoliuretano de mamona, tendo como objetivo utilizar como isolantes t?rmicos para o mercadoconsumidor. Na etapa experimental o rejeito de telha foi mo?do e peneirado ? 200 mesh ecaracterizados por fluoresc?ncia de raios-X (FRX), difra??o de raios-X ( DRX), Microscopiaeletr?nica de varredura (MeV) e granulometria a laser, para analisar os elementos constituintes,fases presentes, defeitos e tamanho do gr?o. Para a fabrica??o da espuma r?gida do poliuretano demamona puro, foram utilizados dois componentes polim?ricos A e B nas propor??es de 1:1,6.Foram desenvolvidas cinco formula??es: FI, FII, FIII, FIV, FV e FVI (0%, 10%, 20%, 30%, 40%,e 50 % de rejeito de telha, respectivamente) para fabrica??o do comp?sito. As propriedadesmec?nicas foram determinadas atrav?s de ensaios de compress?o e ensaio Shore A. J? aspropriedades t?rmicas foram determinadas a partir de ensaios de condutividade t?rmica, calorespec?fico, difusividade t?rmica, absor??o de ?gua e massa especifica. Os resultados morfol?gicosdo comp?sito apresentaram aglomerados de poros fechados, o que p?de ter contribu?do para aredu??o da resist?ncia e da massa espec?fica mec?nica, principalmente da formula??o FVI. Assim,foi percebido que o aumento do teor de rejeito de telha na matriz do poliuretano n?o modificou aspropriedades termofisicas do material. Contudo, o rejeito de telha contribuiu para diminui??o daquantidade de poliuretano usado na fabrica??o de componentes t?rmicos. Os valores apresentadospelos comp?sitos (rejeito de telha + poliuretano) foram similares na formula??o FIII, FIV e FV.Pois os mesmo n?o variaram muito em rela??o ao poliuretano puro. Com isso o material fabricadopode ser aplicado como isolantes t?rmicos, al?m disto, o seu uso pode contribuir na quest?oambiental, por ser um material biodegrad?vel devido ? utiliza??o do rejeito de telha como mat?riaprima e reduzindo custos de fabrica??o. / Studied a composite reject the base tile and castor oil polyurethane, aiming their use as insulation for the consumer market. In the experimental stage the reject tile was ground and sieved at 200 mesh and characterized by fluorescence X-ray (XRF), diffraction X-ray (XRD), scanning electron microscopy (SEM) and laser granulometry, to analyze the constituent elements, phases present, defects and grain size. For the manufacture of rigid foam polyurethane pure castor two polymer components A and B were used (40- Respan) in the proportions of 1 part to component A and 1.6 parts of component B. six formulations were developed: FI, FII, FIII, FIV, FV and FVI (0%, 10%, 20%, 30%, 40% and 50% reject tile, respectively) for the manufacture of the composite. The mechanical properties were determined by compression testing and hardness testing Shore A. Thermal properties were determined from test thermal conductivity, specific heat, thermal diffusivity. The technological tests were water absorption, bulk density and porosity of the composite Morphological results showed clusters of closed pores, which may have contributed to the reduction of the mechanical strength and density, especially of IVF formulation. It was noted that increasing the tile waste content in the polyurethane matrix did not change the thermo-physical properties of the material. However, the waste tile contributed to decreasing the amount of polyurethane used in the manufacture of thermal components. The values presented the composite properties (tailings tile + polyurethane) were similar in formulations FIII, FIV and FV. The obtained composite can be applied as an insulator and may contribute to the environmental issues because it is a biodegradable material due to the use of tile as raw material waste and reducing manufacturing costs.