Made available in DSpace on 2014-12-17T15:42:16Z (GMT). No. of bitstreams: 1
IzangelaMA_TESE.pdf: 6002351 bytes, checksum: 61a1b03824f174ac0458b386d74608e7 (MD5)
Previous issue date: 2012-03-21 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / In this study five compositions were synthesized zirconia doped with cerium and
neodymium ions in the system Ce10-xNdx Zr90O2 with 0,5 ≤ x ≤ 4,0 using the Pechini
method. The powders were characterized by thermogravimetric analysis, differential thermal
analysis, infrared spectroscopy and X-ray diffraction, with application of Rietveld
refinement of the calcination temperatures of 350?C/3h and 30 minutes at 900?C/3h. All
compositions stabilized with a mixture of cubic and tetragonal phase zirconia. The samples
were pressed into bars and sintered at 1500?C/3h and 1500?C/6h, being characterized by Xray
diffraction, with application of the Rietveld refinement, density and porosity using
Archimedes method, scanning electron microscopy and resistance the three point bending. It
has been observed the increase in strength with increasing sintering temperature for the
compositions x = 2,0 and x = 4,0. For x = 2,0 the main phase was the cubic with 92,56%
with crystallite size of 0,56 μm, density and porosity of 96,82% from 1,36%. For x = 4,0
was a mixture of cubic and tetragonal phase with 21% and 37,98%, respectively. The
crystallite size was 54,21 nm and 49,64 nm with a density porosity of 97,45% and 1,32%
respectively. In the analysis of the fracture surface was observed a greater amount of grain
fracture intragranular type, which contribute to increase the mechanical strength of the
ceramic. Increased addition of the neodymium ion in the crystal lattice of the zirconium
showed a nearly linear behavior with increasing mechanical strength of the zirconia ceramic.
Was obtained a bending resistance of 537 ? 38 MPa for the composition x = 2,0
predominantly attributed to cubic phase with 92,56% / No presente trabalho foram sintetizadas cinco composi??es de zirc?nia dopada com
?ons c?rio e neod?mio no sistema Ce10-x.Ndx Zr90O2 com 0,5 ≤ x ≤ 4,0 com o uso do m?todo
Pechini. Os p?s foram caracterizados por an?lise termogravim?trica, an?lise t?rmica
diferencial, espectroscopia na regi?o do infravermelho e difra??o de raios X, com a
aplica??o do refinamento de Rietveld nas temperaturas de calcina??o de 350?C/3h e 30
minutos a 900?C/3h. Todas as composi??es estabilizaram com mistura de fase tetragonal e
c?bica da zirc?nia. As amostras foram prensadas em forma de barras e sinterizadas a
1500?C/3h e 1500?C/6h, sendo caracterizadas por difra??o de raios X, com a aplica??o do
refinamento de Rietveld, densidade e porosidade usando o m?todo de Arquimedes,
microscopia eletr?nica de varredura e resist?ncia a flex?o em tr?s pontos. Foi observado o
aumento da resist?ncia mec?nica com o aumento da temperatura de sinteriza??o para as
composi??es x=2,0 e x=4,0. Para x=2,0 a fase principal foi ? c?bica com 92,56 % com
tamanho de cristalito de 0,56 μm, densidade de 96,82 % e porosidade de 1,36 %. Para x=4,0
ocorreu uma mistura da fase tetragonal e c?bica com 21 % e 37,98 %, repectivamente. O
tamanho de cristalitos foi de 54,21 nm e 49,64 nm, com densidade de 97,45 % e porosidade
de 1,32 %, respectivamente. Nas an?lises da superf?cie de fratura foi observado uma maior
quantidade de gr?os com fratura do tipo intragranular, na qual contribuiu para o aumento da
resist?ncia mec?nica da cer?mica. O aumento da adi??o do ?on neod?mio na rede cristalina
da zirc?nia apresentou um comportamento quase linear com o aumento da resist?ncia
mec?nica da cer?mica de zirc?nia. Foi obtida uma resist?ncia a flex?o de 537 ? 38 MPa para
a composi??o x=2,0 atribu?da a predomin?ncia da fase c?bica com 92,56 %
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/17754 |
| Date | 21 March 2012 |
| Creators | Andrade, Izangela Marculino de |
| Contributors | CPF:02168290890, http://lattes.cnpq.br/9213856023536973, Cavalcante, Maria Gorette, CPF:10843329491, http://lattes.cnpq.br/2069510469317474, Oliveira, Jo?o Bosco Lucena de, CPF:19127537404, http://lattes.cnpq.br/1360004695124740, Pessoa, R?gia Chacon, CPF:03620014485, http://lattes.cnpq.br/4364242357184993, Lima, Ulisandra Ribeiro de, CPF:02824707437, http://lattes.cnpq.br/0610156933803056, Nasar, Ricardo Silveira |
| Publisher | Universidade Federal do Rio Grande do Norte, Programa de P?s-Gradua??o em Qu?mica, UFRN, BR, F?sico-Qu?mica; Qu?mica |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/doctoralThesis |
| Format | application/pdf |
| Source | reponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN |
| Rights | info:eu-repo/semantics/openAccess |
Page generated in 0.0022 seconds