Banca de QUALIFICAÇÃO: GABRIEL CLINT GONCALVES

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
DISCENTE : GABRIEL CLINT GONCALVES
DATA : 11/12/2019
HORA: 14:00
LOCAL: sala 306, 3º andar, Bloco B, Campus SA da Fundação Universidade Federal do ABC, localizada na Avenida dos Estados, 5001, Santa Terezinha, Santo André, SP
TÍTULO:

Strengthening by chemical tempering of lanthanum oxide-containing aluminoborosilicate glasses

PÁGINAS: 56
GRANDE ÁREA: Engenharias
ÁREA: Engenharia de Materiais e Metalúrgica
SUBÁREA: Materiais Não-Metálicos
ESPECIALIDADE: Cerâmicos
RESUMO:

Aluminoborosilicate glasses containing rare earth oxides have high values of mechanical properties and refractive index. The aim of this study was to verify the feasibility of strengthening by ion-exchange (chemical tempering) this type of glass as an alternative to counterbalance the high cost of rare earth oxides and to improve the mechanical properties in an aluminoborosilicate glass with La₂O₃. SiO₂-B₂O₃-Al₂O₃-La₂O₃-TiO₂ and SiO₂-B₂O₃-Al₂O₃-La₂O₃-TiO₂-Na₂O glass compositions were investigated in order to verify the necessity of an addition of an alkaline earth oxide to promote the ion exchange. The sodium oxide content was varied as 5, 10 and 15 mol%. The glasses were chemically tempered with KNO₃ salt at 600, 650 and 700 ^oC. Before and after the tempering, the X-ray diffraction analysis (XRD) did not identify the presence of crystalline phases and the energy dispersive spectroscopy analysis (EDS) detected K in the second composition, indicating the effectiveness of ion exchange between sodium and potassium. After the tempering, the Vickers's hardness raised to approximately 7.5 GPa. In sodium-containing composition, compressive residual stress was observed and the fracture toughness (K_Ic) determined by indentation fracture analysis increased.

MEMBROS DA BANCA:
Presidente - Interno ao Programa - 1761015 - RENATA AYRES ROCHA
Membro Titular - Examinador(a) Externo à Instituição - ANTONIO CARLOS DA SILVA
Membro Titular - Examinador(a) Externo à Instituição - CATIA FREDERICCI - IPT-SP
Membro Suplente - Examinador(a) Interno ao Programa - 1948454 - VANIA TROMBINI HERNANDES
Membro Suplente - Examinador(a) Interno ao Programa - 1676364 - JULIANA MARCHI