Banca de DEFESA: RENATA ROBERTI BENEVIDES

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : RENATA ROBERTI BENEVIDES
DATE: 28/02/2023
TIME: 14:30
LOCAL: Santo André
TITLE:

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

PAGES: 90
BIG AREA: Engenharias
AREA: Engenharia de Materiais e Metalúrgica
SUBÁREA: Materiais Não-Metálicos
SPECIALTY: Cerâmicos
SUMMARY:

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.

COMMITTEE MEMBERS:
Presidente - Interno ao Programa - 1545089 - DANIEL ZANETTI DE FLORIO
Membro Titular - Examinador(a) Interno ao Programa - 1305186 - SERGIO BROCHSZTAIN
Membro Titular - Examinador(a) Interno ao Programa - 1671394 - HUMBERTO NAOYUKI YOSHIMURA
Membro Titular - Examinador(a) Externo à Instituição - IEDA MARIA GARCIA DOS SANTOS
Membro Titular - Examinador(a) Externo à Instituição - FABIANE DE JESUS TRINDADE
Membro Suplente - Examinador(a) Interno ao Programa - 1545738 - MARCIA TSUYAMA ESCOTE
Membro Suplente - Examinador(a) Externo ao Programa - 1761015 - RENATA AYRES ROCHA
Membro Suplente - Examinador(a) Externo ao Programa - 1948454 - VANIA TROMBINI HERNANDES
Membro Suplente - Examinador(a) Externo à Instituição - SILAS DERENZO
Membro Suplente - Examinador(a) Externo à Instituição - LUIS A. GENOVA