@MastersThesis{FlórezVergara:2019:12BaX,
author = "Fl{\'o}rez Vergara, Diego Ediss{\'o}n",
title = "Espumas de carbono de origem sustentav{\'e}l como material
absorvedor de radia{\c{c}}{\~a}o eletromagn{\'e}tica na faixa
de micro-ondas 8,2 - 12,4 (banda X)",
school = "Instituto Nacional de Pesquisas Espaciais (INPE)",
year = "2019",
address = "S{\~a}o Jos{\'e} dos Campos",
month = "2019-05-29",
keywords = "Absorvedor de radia{\c{c}}{\~a}o eletromagn{\'e}tica, espumas
de carbono, carbono poroso, material comp{\'o}sito,
sustentabilidade, electromagnetic radiation absorber, frequency
selective surfaces, carbon foam, composite material,
sustainability.",
abstract = "Este trabalho descreve a s{\'{\i}}ntese e
caracteriza{\c{c}}{\~a}o de espumas de carbono de natureza
renov{\'a}vel e sua aplicabilidade no setor aeroespacial na
redu{\c{c}}{\~a}o da se{\c{c}}{\~a}o transversal do radar
(Radar Cross Section Reduction - RCSR) atrav{\'e}s da seu uso
como; (i) material absorvedor de radia{\c{c}}{\~a}o
eletromagn{\'e}tica (MARE) e (ii) superf{\'{\i}}cies seletoras
de frequ{\^e}ncia (Frequency Selective Surface - FSS). Na
atualidade, devido ao avan{\c{c}}o da eletr{\^o}nica moderna e
dos circuitos integrados, os MAREs t{\^e}m encontrado uma
expans{\~a}o gradual em outros setores al{\'e}m do
aeron{\'a}utico e aeroespacial, tais como; nas
telecomunica{\c{c}}{\~o}es, na computa{\c{c}}{\~a}o,
automa{\c{c}}{\~a}o e medicina, onde a demanda por estes
materiais tem aumentado consideravelmente com o objetivo de
proteger os sistemas e dispositivos envolvidos de
interfer{\^e}ncias eletromagn{\'e}ticas que possam comprometer o
seu funcionamento e/ou desempenho. O material desenvolvido neste
trabalho foi submetido a um processo de s{\'{\i}}ntese realizado
atrav{\'e}s da mistura do licor negro como precursor principal
junto a precursores secund{\'a}rios que auxiliam no seu processo
de cura e predeterminam algumas propriedades finais do material.
Em seguida, {\'e} realizado um processo de pir{\'o}lise para a
obten{\c{c}}{\~a}o de um material final altamente rico em
carbono, para um posterior processo de caracteriza{\c{c}}{\~a}o
do material, tendo por objetivo descrever a sua estrutura,
composi{\c{c}}{\~a}o, morfologia e propriedades
eletromagn{\'e}ticas na faixa de frequ{\^e}ncia de 8,2 {\`a}
12,4 GHz. No entanto, para a obten{\c{c}}{\~a}o das propriedades
eletromagn{\'e}ticas do material, {\'e} necess{\'a}rio a
produ{\c{c}}{\~a}o de materiais comp{\'o}sitos que s{\~a}o
feitos misturando o material carbonoso com matrizes estruturais de
borracha de silicone ou resina ep{\'o}xi, cujos formatos
geom{\'e}tricos s{\~a}o definidos pelo equipamento
respons{\'a}vel da analise, neste caso, o analisador vetorial de
redes VNA (N5230C PNA-L) com kit de calibra{\c{c}}{\~a}o WR90
X11644A. Assim, avaliou-se o potencial do material na
redu{\c{c}}{\~a}o da se{\c{c}}{\~a}o transversal do radar
atrav{\'e}s de: (I) tipo e concentra{\c{c}}{\~a}o do material
carbonoso; (II) porosidade; (III) geometria superficial; (IV)
matriz estrutural e; (V) espessura dos materiais comp{\'o}sitos.
Pode se concluir assim que para o carbono poroso em matriz
estrutural de borracha de silicone obtiveram-se como resultados
mais significativos aqueles referentes {\`a}s amostras com
maiores concentra{\c{c}}{\~o}es de carbono (20%), espessura de 2
mm e porosidade de 300 \μm < ø3 < 420 \μm, conseguindo
uma absor{\c{c}}{\~a}o da energia eletromagn{\'e}tica incidente
de -33,34 dB em 9,87 GHz. Para o carbono poroso com matriz
estrutural de resina ep{\'o}xy, a absor{\c{c}}{\~a}o mais
significativa foi obtida para as amostras com maiores
concentra{\c{c}}{\~o}es de carbono (15%), espessura de 2 mm,
porosidade de 180 \μm < ø3 < 250 \μm, tamanho de
part{\'{\i}}cula de 250 < ø2 < 425 e sem
transforma{\c{c}}{\~a}o para superf{\'{\i}}cies seletoras de
frequ{\^e}ncia, conseguindo uma absor{\c{c}}{\~a}o de -18,86 dB
em 11,79 GHz. Finalmente, para o carbono+MnSO4.H2O com matriz
estrutural de resina ep{\'o}xy, a absor{\c{c}}{\~a}o mais
significativa foi obtida para as amostras com maiores
concentra{\c{c}}{\~o}es de carbono (20%), espessura de 2 mm e
tamanho de part{\'{\i}}cula de '3 > 63 \μm, conseguindo
uma absor{\c{c}}{\~a}o de -18,37 dB em 8,40 GHz. ABSTRACT: This
research worked on the synthesis and characterization of carbon
foams from renewable nature, and their applicability in the
aerospace sector as radar crosssection reduction (RCSR) through
techniques such as; (i) radar absorbing material (RAM) and (ii)
frequency selective surfaces (FSS). Due to the advance of modern
electronics and integrated circuits, RAMs have found a gradual
expansion in other sectors besides aeronautical and aerospace;
such as, telecommunications, computing, automation, and medicine,
where the demand for these materials has increased considerably in
order to protect the systems and devices involved from
electromagnetic interference that could compromise their operation
and/or performance. To predetermine the final properties of the
material that was being studied, It was subjected to a synthesis
process performed by mixing the black liquor as the main precursor
together with secondary precursors that aid in its curing process.
Next, a pyrolysis process was carried out to obtain a material
highly rich in carbon, for a later process of characterization of
the material, having as an objective the description of its
structure, composition, morphology and electromagnetic properties
(in the frequency range of 8.2 to 12.4 GHz). To obtain the
electromagnetic properties of the material, it was necessary to
produce composite materials that were made by mixing the
carbonaceous material with structural matrices of silicone rubber
or epoxy resin, whose geometric shapes were defined by the
responsible equipment for the electromagnetic analysis; in this
case, a network vector analyzer (VNA N5230C PNA-L) with the
calibration kit WR90 X11644A. Thus, the potential of the material
for the RCSR was evaluated through; (I) type and concentration of
the carbonaceous material, (II) porosity, (III) surface geometry,
(IV) structural matrix and, (V) thickness of the composite
materials. Therefore, can be concluded that for porous carbon in
silicon rubber structural matrix, the most significant results
were obtained for the samples with the highest concentrations of
carbon (20%), thickness of 2 mm and porosity of 300 \μm < ø3
< 420 \μm, with an incident electromagnetic energy
absorption of -33.34 dB at 9.87 GHz. For the porous carbon with
the epoxy resin structural matrix, the most significant absorption
was obtained for the samples with higher carbon concentrations
(15%), thickness of 2 mm, porosity of 180 \μm < ø3 < 250
\μm, particle size of 250 < ø2 < 425 and without
transformation to frequency selective surfaces, achieving an
absorption of -18.86 dB at 11.79 GHz. Finally, for
carbono+MnSO4.H2O with an epoxy resin structural matrix, the most
significant absorption was obtained for the samples with the
highest carbon concentrations (20%) and thickness of 2 mm and
particle size of '3 > 63 \μm, achieving an absorption of
-18.37 dB at 8.40 GHz.",
committee = "Baldan, Maur{\'{\i}}cio Ribeiro (presidente/orientador) and
Labat, Gisele Aparecida Amaral (orientadora) and Mineiro, Sergio
Luiz and Quirino, Sandro Fonseca and Boss, Alan Fernando Ney",
englishtitle = "Carbon foams of sustainable origin as electromagnetic radiation
absorbing material in the 8.2 -12.4 GHz microwave range (X Band)",
language = "pt",
pages = "137",
ibi = "8JMKD3MGP3W34R/3TBGFMH",
url = "http://urlib.net/ibi/8JMKD3MGP3W34R/3TBGFMH",
targetfile = "publicacao.pdf",
urlaccessdate = "19 abr. 2024"
}