@MastersThesis{Alves:2017:EsObCa,
author = "Alves, Adriano Cavalca",
title = "Estudo da obten{\c{c}}{\~a}o e caracteriza{\c{c}}{\~a}o de
aluminas alfa nanoparticuladas via s{\'{\i}}ntese
qu{\'{\i}}mica e tratamento t{\'e}rmico convencional",
school = "Instituto Nacional de Pesquisas Espaciais (INPE)",
year = "2017",
address = "S{\~a}o Jos{\'e} dos Campos",
month = "2017-05-29",
keywords = "nanoparticulado, aluminas de transi{\c{c}}{\~a}o, alumina alfa,
aglomerados, s{\'{\i}}ntese sol-gel, nanoparticulate, transition
aluminas, alumina alfa, clusters, sol-gel synthesis.",
abstract = "O objetivo principal deste trabalho foi estudar e determinar os
par{\^a}metros de processamento e procedimentos para
obten{\c{c}}{\~a}o de p{\'o}s nanoparticulados de aluminas de
transi{\c{c}}{\~a}o e alumina est{\'a}vel (\$\alpha\$).
Estes materiais foram obtidos via s{\'{\i}}ntese sol-gel, por
precipita{\c{c}}{\~a}o a partir de solu{\c{c}}{\~a}o aquosa de
nitrato de alum{\'{\i}}nio
[Al(NO\$_{3}\$)\$_{3}\$.9H\$_{2}\$O] com hidr{\'o}xido de
am{\^o}nio (NH\$_{4}\$OH), obtendo alumina hidratada, e
subsequentes tratamentos t{\'e}rmicos at{\'e} 1200\$^{o}\$C.
Para estudo da forma{\c{c}}{\~a}o de aglomerados e agregados das
part{\'{\i}}culas precipitadas, estas foram solvatadas com
subst{\^a}ncias qu{\'{\i}}micas com tamanhos de mol{\'e}culas
e polaridades diferentes: {\'a}gua, {\'a}lcool et{\'{\i}}lico
e {\'a}cido ac{\'e}tico. As obten{\c{c}}{\~o}es das aluminas
de transi{\c{c}}{\~a}o e est{\'a}vel (\$\alpha\$) foram
feitas utilizando tratamentos t{\'e}rmicos em forno convencional.
Na etapa de solvata{\c{c}}{\~a}o das part{\'{\i}}culas das
aluminas hidratadas precipitadas estudou-se o efeito da secagem
est{\'a}tica (na temperatura ambiente) no estado de
aglomera{\c{c}}{\~a}o/agrega{\c{c}}{\~a}o destas
part{\'{\i}}culas dos p{\'o}s. De forma comparativa estudou-se
as caracter{\'{\i}}sticas morfol{\'o}gicas dos p{\'o}s de
alumina obtidos em diferentes calcina{\c{c}}{\~o}es em forno
convencional em rela{\c{c}}{\~a}o {\`a} forma{\c{c}}{\~a}o de
aglomerados e agregados em fun{\c{c}}{\~a}o da temperatura e
tempo no tratamento t{\'e}rmico. Os p{\'o}s foram caracterizados
quanto {\`a} morfologia, forma e estado de
aglomera{\c{c}}{\~a}o/agrega{\c{c}}{\~a}o por FEG-MEV
(microsc{\'o}pio eletr{\^o}nico de varredura de alta
resolu{\c{c}}{\~a}o), identifica{\c{c}}{\~a}o das fases
cristalinas por difratometria de raios X (DRX) e
determina{\c{c}}{\~a}o da {\'a}rea espec{\'{\i}}fica pelo
m{\'e}todo BET (Brunauer Emmett Telller). De acordo com os
resultados de caracteriza{\c{c}}{\~a}o as aluminas tratadas
at{\'e} 1100\$^{°}\$C s{\~a}o compostas por
nanopart{\'{\i}}culas aglomeradas, e partir de 1200\$^{°}\$C
por part{\'{\i}}culas submicrom{\'e}trica. A alumina hidratada
e solvatada, com solu{\c{c}}{\~a}o aquosa de {\'a}cido
ac{\'e}tico a 40 \%, al{\'e}m de ser nanoparticulada,
apresentou a menor temperatura de forma{\c{c}}{\~a}o de fase
cristalina est{\'a}vel (fase \$alpha\$) ap{\'o}s
calcina{\c{c}}{\~a}o em 1100 \$^{°}\$C. ABSTRACT: The main
objective of this work was to study and determine the processing
parameters and procedures for obtaining nanoparticulate powders of
transition aluminas and stable alumina (\$\alpha\$). These
materials were obtained by sol-gel synthesis by precipitation from
aqueous solution of aluminum nitrate [Al (NO3) 3.9H2O] with
ammonium hydroxide (NH\$_{4}\$OH), obtaining hydrated alumina,
and subsequent thermal treatments up to 1200\$^{°}\$C. To study
the formation of clusters and clusters of precipitated particles,
they were solvated with chemicals of different molecule sizes and
polarities: water, ethyl alcohol and acetic acid. The transition
and stable alumina (\$\alpha\$) were obtained using
conventional furnace heat treatments. In the solvation step of the
precipitated hydrated alumina particles, the effect of static
drying (at room temperature) on the agglomeration / aggregation
state of these powders particles was studied. In a comparative
way, the morphological characteristics of the alumina powders
obtained in different conventional kiln calcination were studied
in relation to the formation of agglomerates and aggregates as a
function of temperature and time in the heat treatment. The
powders were characterized in terms of morphology, shape and state
of agglomeration / aggregation by FEG-MEV (high resolution
scanning electron microscope), identification of crystalline
phases by X-ray diffractometry (XRD) and determination of the
specific area by BET method Brunauer Emmett Telller). According to
the characterization results the aluminas treated up to 1100
\$^{°}\$ C are composed of agglomerated nanoparticles, and from
1200 \$^{°}\$ C by submicron particles. The alumina hydateded
obtained from solvatation with acetic acid and calcined at 1100
\$^{o}\$C, resulted in nanoparticles agglomerates and
\$\alpha\$ alumina.",
committee = "Nono, Maria do Carmo de Andrade (presidente/orientadora) and
Mineiro, Sergio Luiz (orientador) and Machado, Jo{\~a}o Paulo
Barros and Assis, Jo{\~a}o Marcos Kruszynski de",
englishtitle = "Study of the obtaination and characterization of
\α-nanoparticulated alumines via chemical synthesis and
conventional thermal treatment",
language = "pt",
pages = "81",
ibi = "8JMKD3MGP3W34P/3NTHB8L",
url = "http://urlib.net/ibi/8JMKD3MGP3W34P/3NTHB8L",
targetfile = "publicacao.pdf",
urlaccessdate = "27 abr. 2024"
}