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Previous issue date: 2016-04-29 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Neste trabalho foram conformados substratos cer?micos de zirc?nia nanoparticulada estabilizada com 3 mol% de ?tria pelo processo de colagem de fitas (?tape casting?) em meio aquoso em uma faixa de espessura de 100 e 150 ?m, os quais apresentam grande interesse tecnol?gico para aplica??es eletroeletr?nicas. Suspens?es para a colagem de fitas foram preparadas em duas diferentes composi??es: 20% ligante - 22% solvente e 25% ligante - 17% solvente (em peso). Uma emuls?o acr?lica comercial serviu como ligante. A estabilidade da suspens?o de zirc?nia estabilizada com ?tria foi analisada por medida de reologia, atrav?s de curvas de viscosidade. Ambas as suspens?es apresentaram comportamento pseudopl?stico, o que ? desej?vel para a t?cnica de colagem de fitas. Ap?s o processo de colagem realizou-se prensagem uniaxial em diferentes temperaturas (40?C e 60?C) e tempos (5 e 10 minutos) nas fitas cer?micas, para a conforma??o dos laminados. An?lise T?rmica Diferencial (ATD) e Termogravim?trica (ATG) foram realizadas para se definir os par?metros para a sinteriza??o dos laminados. Ap?s a sinteriza??o ? 1500?C foram realizados ensaios de Difra??o de Raios X, densidade e porosidade, resist?ncia mec?nica ? flex?o, microdureza Vickers e Microscopia Eletr?nica de Varredura (MEV) para se avaliar as propriedades dos laminados obtidos al?m de analisar o tamanho e crescimento do gr?o. As amostras laminadas em menores temperaturas de prensagem apresentaram delamina??o entre as interfaces das fitas cer?micas, por?m sem influ?ncia significativa no comportamento mec?nico destes materiais. A composi??o com maior teor de ligante apresentou maiores valores de resist?ncia mec?nica devido ? maior quantidade deste componente propiciar melhorias no processo de conforma??o dos laminados. / Various processing techniques are based on the suspension of ceramics particles in an aqueous or non-aqueous media. One of these techniques is called tape casting, which need of a stabilized suspension with high concentration of solids and adequate rheological behavior, which can define if a process route is viable or not. Typical tape cast slurries are prepared by dispersion of a powder in an organic or nonorganic solvent, with a dispersant, followed by the addition of binders, plasticizers, and other additives. These slurries are cast through a so-called doctor blade over a flat carrier. In this study were shaped ceramic substrates of nanoparticulate zirconia stabilized with 3 mol% yttria by tape casting process in aqueous medium at thickness range of 100 to 150 micrometers which have great technological interest for applications electro-electronic. Tape casting slurries were prepared with two different compositions: 20% binder ? 22% solvent e 25 % binder - 17% solvent (wt.%). A commercial acrylic emulsion served as binder. The stability of the yttria-stabilized zirconia slurries was analyzed by means of rheological characterization through viscosity curves. Both slurries showed a pseudoplastic behavior, which is desired for tape casting. After the tape casting process was made uniaxial pressing at different temperatures (40?C and 60?C) and time (5 and 10 minutes) in ceramic tapes for forming the laminates. Differential Thermal Analysis (DTA) and thermogravimetry (TGA) were performed to define the parameters for the sintering of the laminate. After sintering at 1500?C were performed X Ray Diffraction (XRD), density and porosity, flexural strength, microhardness and Scanning Electron Microscopy (SEM) to evaluate the properties of the obtained laminates. Laminated samples at lower press temperatures showed delamination between the interfaces of the ceramic tapes, however no significant influence on the mechanical behavior of these materials. The composition with higher binder content shows higher values of mechanical resistance due the greater amount of this component provide improvements in the laminate forming process
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/21416 |
| Date | 29 April 2016 |
| Creators | Ara?jo, Micheline dos Reis |
| Contributors | 50580396720, http://lattes.cnpq.br/5460040602567184, Delmonte, Maur?cio Roberto Bomio, 27816279841, http://lattes.cnpq.br/9558299312183852, Melo, Maxymme Mendes de, 00846136457, http://lattes.cnpq.br/3779445657082353, Silva, Vamberto Monteiro da, 67456863415, http://lattes.cnpq.br/7962325767490100, Torquato, Wagner Lopes, 03145621416, http://lattes.cnpq.br/1958198498744966, Acchar, Wilson |
| 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/doctoralThesis |
| 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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