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Previous issue date: 2017-07-31 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / A diatomita possui uma grande variedade de aplica??es devido as suas propriedades f?sicas e qu?micas, sendo utilizada amplamente como material filtrante por causa da sua elevada porosidade. ? um material que, tamb?m, apresenta propriedades diel?tricas quando no seu estado natural. Neste trabalho, estudou-se a obten??o de uma fita cer?mica produzida a partir da diatomita atrav?s do processo de tape casting, para ser aplicado como em capacitores diel?tricos. A mat?ria-prima (diatomita) foi caracterizada atrav?s dos ensaios de particulometria, difra??o de raio x (DRX), fluoresc?ncia de raio x (FRX), microscopia eletr?nica de varredura (MEV), e por espectroscopia de infravermelho com transformada de Fourier (FTIR). A fita cer?mica foi obtida atrav?s do preparo de uma barbotina com p? de diatomita, solvente, dispersante, ligante, plastificante e antiespumante; a mistura dos materiais foi realizada em um moinho de bolas. Foi realizado o ensaio de reologia para avaliar a viscosidade da suspens?o. A barbotina foi colada sobre um filme e, ap?s 24 horas, foi retirada a fita verde, que foi caracterizada atrav?s de an?lise t?rmica diferencial e termogravim?trica (ATD\ATG), DRX, FRX e MEV. Foi constru?do um capacitor cer?mico diel?trico (prot?tipo) com a fita verde, no qual foram realizadas as medidas el?tricas de capacit?ncia e resist?ncia, e foi obtida a constante diel?trica do material (fita diatomita). A fita verde passou por um tratamento t?rmico para a elimina??o dos org?nicos a uma temperatura de 600?C e com uma taxa de aquecimento de 0,5 ?C\min. A sinteriza??o foi realizada em tr?s temperaturas diferentes (1000?C, 1150?C e 1250?C), com uma taxa de aquecimento de 5?C\min. e isoterma de 60 min. A mesma foi ent?o caracterizada atrav?s das an?lises de DRX, MEV, e medidas de densidade e porosidade. Foi observado que as amostras sinterizadas apresentaram muita porosidade na sua microestrutura, entretanto, para as temperaturas de sinteriza??omaiores, houve uma redu??o dessa porosidade. A morfologia da diatomita se manteve para as fitas a verde e sinterizadas, mostrando a sua forma navicular e tubular. A presen?a de poros deve-se a uma caracter?stica t?pica da mat?ria prima (diatomita) utilizada, como tamb?m aos par?metros de processamento, que influenciaram significativamente nas propriedades diel?tricas do material, particularmente da fita a verde. / Diatomite has a wide variety of applications due to its physical and chemical properties and is widely used as a filter material because of its high porosity. It is a material that also has dielectric properties when in its natural state. In this work, a dielectric tape produced from the diatomite was studied through the tape casting process, to be applied in ceramic capacitors. The raw material (diatomite) was characterized by particulometry, X-ray diffraction (XRD), X-ray fluorescence (FRX), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) ). The ceramic tape was obtained by the preparation of a slip with diatomite powder, solvent, dispersant, binder, plasticizer and antifoam; The mixing of the materials was carried out in a ball mill. The rheology test was performed to evaluate the viscosity of the suspension. The slip was glued onto a film and, after 24 hours, the green ribbon was removed, which was characterized by differential thermal and thermogravimetric analysis (ATD \ ATG), DRX, FRX and MEV. A ceramic capacitor (prototype) was built with the green ribbon, in which the electrical capacitance and resistance measurements were performed, and the dielectric constant of the material (diatomite tape) was obtained as a function of the frequency used. The green ribbon underwent a heat treatment, for the removal of organics, at a temperature of 600 ? C and a heating rate of 0.5 ? C / min. The sintering was performed at three different temperatures (1000 ? C, 1150 ? C and 1250 ? C), with a heating rate of 5 ? C / min. And 60 min isotherm. The sintered tape was characterized by the XRD and SEM analyzes, and the results obtained for the measurements of density and porosity. It was observed that the sintered samples presented high porosity in their microstructure, however, for the higher sintering temperatures, there was a reduction of this porosity. The diatomite morphology was maintained for the green and sintered bands, showing its navicular and tubular shape. The presence of pores is due to a typical characteristic of the raw material (diatomite) used, as well as to the processing parameters, which significantly influenced the physical and dielectric properties of the material, particularly green tape. The crystalline structure, the microstructure, and the values of density and porosity obtained for the sintered tape varied according to the dilatometric behavior of the material due to alotropic transformations of the diatomite with temperature. The values of dielectric constants ranged from approximately 123.78 to 17.73 for low and high frequencies, respectively, of the green ribbon.
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/24002 |
| Date | 31 July 2017 |
| Creators | Macedo, Amanda Regina de Souza |
| Contributors | 05012180410, Silva, Ariadne de Souza, 00735940401, Souza, Carlson Pereira de, 13681389420, Oliveira, Leiliane Alves de, 01081015411, Gomes, Uilame Umbelino |
| Publisher | PROGRAMA DE P?S-GRADUA??O EM CI?NCIA E ENGENHARIA DE MATERIAIS, UFRN, Brasil |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Source | reponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN |
| Rights | info:eu-repo/semantics/openAccess |
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