Título: | SYNTHESIS BY HYDROGEN REDUCTION AND CHARACTERIZATION OF THE NI-CO ALLOY | ||||||||||||||||||||||||||||||||||||||||
Autor: |
DANIELA WERNECK DE MACEDO |
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Colaborador(es): |
EDUARDO DE ALBUQUERQUE BROCCHI - Orientador IVAN GUILLERMO SOLORZANO NARANJO - Coorientador |
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Catalogação: | 17/MAR/2006 | Língua(s): | PORTUGUESE - BRAZIL |
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Tipo: | TEXT | Subtipo: | THESIS | ||||||||||||||||||||||||||||||||||||||
Notas: |
[pt] Todos os dados constantes dos documentos são de inteira responsabilidade de seus autores. Os dados utilizados nas descrições dos documentos estão em conformidade com os sistemas da administração da PUC-Rio. [en] All data contained in the documents are the sole responsibility of the authors. The data used in the descriptions of the documents are in conformity with the systems of the administration of PUC-Rio. |
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Referência(s): |
[pt] https://www.maxwell.vrac.puc-rio.br/projetosEspeciais/ETDs/consultas/conteudo.php?strSecao=resultado&nrSeq=7943&idi=1 [en] https://www.maxwell.vrac.puc-rio.br/projetosEspeciais/ETDs/consultas/conteudo.php?strSecao=resultado&nrSeq=7943&idi=2 |
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DOI: | https://doi.org/10.17771/PUCRio.acad.7943 | ||||||||||||||||||||||||||||||||||||||||
Resumo: | |||||||||||||||||||||||||||||||||||||||||
It has been clear the increasing importance of
nanostructured materials in the
present scientific and technological developments due to
their unique properties. It
is also well established that properties of materials can
be severely altered by
making them to reach a nanostructured condition.
The present work presents an alternative route for obtain
nanoestructured nickelcobalt
alloy. The methodology is based on the dissociation of the
metal nitrates in
a very small oxides particles, even nanometric ones, and
subsequent hydrogen
reduction of the obtained oxides. Thermodynamic studies
have been developed to
support the feasibility of the reactions carried out to
obtain nickel and cobalt
oxides as well as the metals particles.
Nickel and cobalt oxides were produced, either isolated or
co-formed, by
dehydrating a water dissolved homogeneous solution of Ni
(NO3)2 or/and
Co(NO3)2 at 400oC for about three hours. X-ray diffraction
has been carried out to
confirmed the Co3O4 and NiO formation. Transmission
Electron Microscopy
(TEM) studies have shown nanoscale structures with
different morphology and
size distribution.
Hydrogen reduction was applied to obtain Ni, Co and Ni0.5-
Co0.5 alloy. The
temperature and hydrogen partial pressure range studied
were, respectively,
200oC-500oC and 0,4-1,0atm. The NiO reduction showed an
autocatalytic
behavior with Ea = 28,7kJ/mol while the isolated Co3O4 and
the co-formed oxides
reductions followed topochemical reaction model, with Ea =
33,7kJ/mol and
29,7kJ/mol, respectively.
The Ni-Co alloy synthesis reaction showed a first order
behavior. The TEM
studies have revealed a Ni-Co alloy constituted by
nanoscale single crystals of
about 20nm in size.
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