Banca de QUALIFICAÇÃO: DÉBORA CRISTINA OLIVEIRA DE SOUZA NEVES
Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.DISCENTE : DÉBORA CRISTINA OLIVEIRA DE SOUZA NEVES
DATA : 30/06/2022
HORA: 14:00
LOCAL: Santo André
TÍTULO:
“Preparation and characterization of BaZr0,4Ce0,4Y0,1Gd 0,1O3-δ perovskite protonic fuel cells”
PÁGINAS: 100
GRANDE ÁREA: Engenharias
ÁREA: Engenharia de Materiais e Metalúrgica
SUBÁREA: Materiais Não-Metálicos
ESPECIALIDADE: Cerâmicos
RESUMO:
One of the great challenges of the last 20 years has been searching for ways to generate
and convert energy using renewable sources and clean technologies. Such technologies
aim to minimize the effects of global warming and replace the use of compounds from
fossil fuels. Fuel cells have been studied for this purpose since 1958 and have drawn the
attention of researchers worldwide for presenting themselves as a viable alternative to
replace the fossil fuel matrices currently used. Among the solid oxide cells studied, the
ABO 3 type perovskites, which are composed of barium cerates and zirconates, stand out
for the application of proton conduction. Cerates and zirconates have high acceptability
of alliovalent dopants in their crystalline structure, thus generating oxygen vacancies
that favor the increase of the cell's proton conduction. Furthermore, the combination of
properties of cerates with doped zirconates shows good compatibility of properties since
the presence of Ce increases proton conductivity while Zr increases chemical stability.
When combined, they present high chemical instability. This finding led to several
scientific studies to evaluate the effects of dopants on the perovskite structure and
overcome their limitations, such as high densification temperature and chemical
instability. Studies show that BaCe 0.8 Gd 0.2 O 3 has low densification and good proton
conduction at lower temperatures, while BaZr 0.8 Y 0.2 O 3 has greater chemical stability but
greater conduction at higher operating temperatures. The present work seeks to develop
an electrolyte based on BaZr 0.4 Ce 0.4 Y 0.1 Gd 0.1 O 3-δ and compare whether there is
improvement in chemical stability, conductivity, and densification at lower
temperatures and for operation at intermediate temperatures (500 - 700°C). Studies of
cells supported on the electrolyte and supported on the anode were also developed. The
cell supported on the electrolyte was obtained by compaction, and the cell supported on
the anode was successfully obtained for 5 layers by co-pressing and co-sintering after
studying the effect of grinding into the starting powder obtained by the pechini method.
Both samples underwent cell tests in fiaxell using synthetic Ar and H 2 as fuel. The
measurements were performed using the impedance spectroscopy (EIS) technique, and
the I-V curves were obtained using open-circuit voltage (OCV). In the present work, a
higher value of OCV (1.1V) was obtained at 500 °C when compared with the previous
ones published in the literature for the sample supported in the electrolyte application.
Also, the samples showed an increase in power density and stability in the OCV after
polarization of 14 h with an atmosphere of 50% H 2 and 50% N 2 , showing promise to be
used as proton fuel cells.
MEMBROS DA BANCA:
Presidente - Interno ao Programa - 667965 - REGINALDO MUCCILLO
Membro Titular - Examinador(a) Interno ao Programa - 1676364 - JULIANA MARCHI
Membro Titular - Examinador(a) Externo ao Programa - 335.741.228-45 - FABIANE DE JESUS TRINDADE
Membro Titular - Examinador(a) Externo à Instituição - DANIEL ARAUJO DE MACEDO - UFPB
Membro Suplente - Examinador(a) Interno ao Programa - 1552290 - ANDRE SANTAROSA FERLAUTO
Membro Suplente - Examinador(a) Externo à Instituição - ELIANA NAVARRO DOS SANTOS MUCCILLO - IPEN
Membro Suplente - Examinador(a) Externo à Instituição - VICTOR BURATTO TINTI
Membro Suplente - Examinador(a) Externo à Instituição - ANDRÉ LUIZ DA SILVA