@MastersThesis{Silva:2021:EsSíQu,
author = "Silva, Isabel Christina Franco",
title = "Estudo da s{\'{\i}}ntese qu{\'{\i}}mica de aluminas
nanoparticuladas com tratamentos t{\'e}rmicos por micro-ondas",
school = "Instituto Nacional de Pesquisas Espaciais (INPE)",
year = "2021",
address = "S{\~a}o Jos{\'e} dos Campos",
month = "2021-07-20",
keywords = "nanopart{\'{\i}}cula, alumina, micro-ondas, s{\'{\i}}ntese
sol-gel, nanoparticle, alumina, microwave, sol-gel synthesis.",
abstract = "O tratamento t{\'e}rmico pelo uso de micro-ondas tem despertado
um grande interesse na pesquisa cient{\'{\i}}fica devido sua
rapidez, simplicidade e efici{\^e}ncia energ{\'e}tica para obter
materiais com caracter{\'{\i}}sticas e propriedades
diferenciadas em n{\'{\i}}vel tecnol{\'o}gico. E como a alumina
{\'e} uma das cer{\^a}micas mais utilizadas na ind{\'u}stria,
por possuir larga aplica{\c{c}}{\~a}o principalmente em
materiais cer{\^a}micos especiais, por ser um material inerte, de
alta dureza e alto ponto de fus{\~a}o, tornarse um fator de
motiva{\c{c}}{\~a}o para o uso desta energia na etapa do
tratamento t{\'e}rmico com o intuito de obter aluminas com
propriedades otimizadas em rela{\c{c}}{\~a}o aquelas obtidas por
m{\'e}todos convencionais. Os diferentes m{\'e}todos de
s{\'{\i}}ntese da alumina, as fases cristalinas e os tamanhos de
part{\'{\i}}culas est{\~a}o intimamente ligados com suas
propriedades. Este trabalho tem como objetivo produzir p{\'o}s
nanopart{\'{\i}}culados de alumina na fase cristalina alfa
(\α). Foram sintetizadas nanopart{\'{\i}}culas de alumina
pelo m{\'e}todo sol-gel por precipita{\c{c}}{\~a}o. Numa
solu{\c{c}}{\~a}o saturada, utilizou-se como reagentes, nitrato
de alum{\'{\i}}nio nonahidratado (Al(NO3)3.9H2O) dissolvido em
{\'a}lcool et{\'{\i}}lico e hidr{\'o}xido de am{\^o}nio
(NH4OH) para precipitar a alumina hidratada ou hidr{\'o}xido de
alum{\'{\i}}nio, identificada como baierita. Ap{\'o}s, o meio
reacional foi exposto a agita{\c{c}}{\~a}o de ultrassom de alta
intensidade (sonotron), atrav{\'e}s de um sistema de sonda de
tit{\^a}nio e imers{\~a}o direta, seguido de
centrifuga{\c{c}}{\~a}o e secagem din{\^a}mica em banho de
ultrassom para minimizar a aglomera{\c{c}}{\~a}o das
nanopart{\'{\i}}culas. As nanopart{\'{\i}}culas de baierita,
obtidas foram caracterizadas por difra{\c{c}}{\~a}o de raios X
(DRX), microscopia eletr{\^o}nica de varredura (MEV) e a
an{\'a}lise de {\'a}rea superficial pelo M{\'e}todo
Brunauer-Emmett-Teller (BET). Os p{\'o}s foram submetidos a
tratamentos em micro-ondas em diferentes temperaturas (800, 900,
1000, 1100 e 1200°C). De acordo com os resultados de
caracteriza{\c{c}}{\~a}o as aluminas tratadas em temperaturas de
at{\'e} 1100 °C por micro-ondas s{\~a}o compostas por
nanopart{\'{\i}}culas e fase cristalina \. No entanto,
a fase cristalina alumina \α est{\'a} presente no p{\'o}
tratado em 1200°C e s{\~a}o formados por
micropart{\'{\i}}culas. Os resultados obtidos neste trabalho
indicam a necessidade de mais estudos deste material, uma vez que
n{\~a}o foi encontrado na literatura informa{\c{c}}{\~o}es que
possam esclarecer este comportamento. ABSTRACT: Thermal treatment
using microwaves has aroused great interest in scientific research
due to its speed, simplicity and energy efficiency to obtain
materials with technologically differentiated characteristics and
properties. Alumina is one of the most widely used ceramics in the
industry, as it has wide application mainly in special ceramic
materials, as it is an inert material, with high hardness and high
melting point. The different methods of alumina synthesis, and the
phases and sizes of particles are closely linked with its
properties. This work aims to produce alpha alumina nanoparticles
(\α). The different methods of alumina synthesis, its phases
and particle sizes are closely linked with its properties;
therefore, the use of microwaves in the heat treatment step in
order to obtain aluminas with different properties from those
obtained by conventional methods is promising. This work aims to
produce alumina nanoparticles in the alpha (\α) phase using
microwaves. Alumina nanoparticles were synthesized by the sol-gel
method through precipitation. In a saturated solution, nonhydrated
aluminum nitrate (Al(NO3)3.9H2O) dissolved in ethyl alcohol and
ammonium hydroxide (NH4OH) was used as reagents to precipitate the
hydrated alumina, or aluminum hydroxide, identified as bayerite.
Afterwards, the reactional system was exposed to high intensity
ultrasound (sonotron) through a titanium probe system and direct
immersion, followed by centrifugation and dynamic drying in an
ultrasound bath to minimize the agglomeration of the
nanoparticles. The baierite nanoparticles obtained were
characterized by X-ray diffraction (XRD), scanning electron
microscopy (SEM) and surface area analysis by the Brunauer
Emmett-Teller Method (BET). The powders were submitted to
microwave treatments at different temperatures (800, 900, 1000,
1100 and 1200°C). According to the characterization results, the
aluminas treated at temperatures up to 1100 °C by microwave are
composed of nanoparticles and a cristalina crystalline phase.
However, the \α alumina crystalline phase is present in the
treated powder at 1200°C and are formed by microparticles. The
results obtained in this work indicate the need for further
studies of this material, since information that could clarify
this behavior was not found in the literature.",
committee = "Nono, Maria do Carmo de Andrade (presidente/orientadora) and
Machado, Jo{\~a}o Paulo Barros and Assis, Jo{\~a}o Marcos
Kruszynski de",
englishtitle = "Study of the chemical synthesis of nanoparticulated alumines with
microwave thermal treatment",
language = "pt",
pages = "53",
ibi = "8JMKD3MGP3W34T/4593FUE",
url = "http://urlib.net/ibi/8JMKD3MGP3W34T/4593FUE",
targetfile = "publicacao.pdf",
urlaccessdate = "04 maio 2024"
}