Banca de QUALIFICAÇÃO: RENATA ROBERTI BENEVIDES

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
DISCENTE : RENATA ROBERTI BENEVIDES
DATA : 03/04/2020
HORA: 14:00
LOCAL: sala 305, 3º andar, Bloco B, Campus SA da Fundação Universidade Federal do ABC, localizada na Avenida dos Estados, 5001, Santa Terezinha, Santo André, SP
TÍTULO:

PREPARATION AND CHARACTERIZATION OF ZrxCe1-xO2-δ SOLID SOLUTION BY MECHANOCHEMICAL REACTION PROCESS IN HIGH ENERGY PLANETARY BALL MILL

PÁGINAS: 85
GRANDE ÁREA: Engenharias
ÁREA: Engenharia de Materiais e Metalúrgica
SUBÁREA: Materiais Não-Metálicos
ESPECIALIDADE: Cerâmicos
RESUMO:

Ball mills have been used by the industry for a long time, but recent technical advances in equipment have increased the scope of their application. High energy mills provide not only the reduction of particle sizes and dispersion, but also the occurrence of mechanochemical reactions. High energy planetary beads mills belong to this class of equipment. Ceria has important characteristics for several applications, such as redox, transport properties and high surface to volume ratio, when compared to other oxides. Despite many advantages, it has a limitation in thermal stability, which compromises its use in some applications. The addition of zirconia improves performance at high temperatures and, consequently, the oxygen storage capacity. In the present work, solid solutions of ZrxCe1-xO2- were obtained by mechanochemical reaction using high energy planetary beads mills. Such mills move the zirconium beads stabilized with yttria, causing collisions that can occur between beads and between the beads and the surfaces of the grinding chamber. The zirconium concentration added to the solutions was 0  x  50. The resulting crystalline structures were characterized by Raman spectroscopy and X-ray diffraction. The results showed that the stress energy obtained by the collisions of the beads reduced the energy barrier from the valence band to the conduction band, which caused the formation of structural defects, oxygen vacancies and tension in the crystalline network. The tension generated was relaxed in two ways: (1) by mechanical activation demonstrated by obtaining nanocrystalline ceria with oxygen vacancies; or (2) by mechanochemical reaction evidenced by the substitution of zirconium in the structure of the ceria.

MEMBROS DA BANCA:
Presidente - Interno ao Programa - 1671394 - HUMBERTO NAOYUKI YOSHIMURA
Membro Titular - Examinador(a) Externo ao Programa - 1305186 - SERGIO BROCHSZTAIN
Membro Titular - Examinador(a) Externo ao Programa - 1948454 - VANIA TROMBINI HERNANDES
Membro Titular - Examinador(a) Externo à Instituição - FABIANE DE JESUS TRINDADE - USP
Membro Suplente - Examinador(a) Interno ao Programa - 2604128 - ALEXANDRE JOSE DE CASTRO LANFREDI
Membro Suplente - Examinador(a) Interno ao Programa - 1545738 - MARCIA TSUYAMA ESCOTE
Membro Suplente - Examinador(a) Externo ao Programa - 1073241 - MARINA SPARVOLI DE MEDEIROS
Membro Suplente - Examinador(a) Externo à Instituição - MAXIMILIANO LUIS MUNFORD - UFV