Banca de DEFESA: LEANDRO ANTONIO DE OLIVEIRA
Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.DISCENTE : LEANDRO ANTONIO DE OLIVEIRA
DATA : 13/03/2020
HORA: 14:00
LOCAL: Campus Santo André
TÍTULO:
Influence of anodizing treatments of the AZ31B magnesium alloy on its corrosion-fatigue behavior in physiological solution
PÁGINAS: 150
GRANDE ÁREA: Engenharias
ÁREA: Engenharia de Materiais e Metalúrgica
SUBÁREA: Metalurgia Física
ESPECIALIDADE: Corrosão
RESUMO:
Many works have been highlighted the use of anodizing treatment to produce protective and non-toxic layers over magnesium alloys. However, most papers are not intended to study the synergistic effect between the degradation on the physiological environment and the cyclic stresses of these biomedical devices during the healing period. The goal of this work is the study of the anodizing treatment of magnesium alloy AZ31B over its corrosion-fatigue behavior. Initially, anodized samples were produced to investigate the effect of the formation electrolyte, voltage, current density and treatment time of the anodizing process on the corrosion behavior of the AZ31B alloy. Scanning electron microscopy and confocal laser scanning microscopy analyzes were performed to evaluate the surface morphology, thickness and roughness of the anodized layers. Next, X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) were analyzed to explore the chemistry surface and the microstructure of the oxide layers and its relationship with the electrochemical behavior. Furthermore, a scanning electrochemical microscopy (SECM) technique was used to identify the local corrosion sites on the surface of the AZ31B alloy, exploring its correlation with the corrosion-fatigue phenomenon. In addition, cytotoxicity experiments were conducted to evaluate its biological responses. Thus, one set of anodization parameter was chosen to proceed the investigation by doing the fatigue tests in the air. The results showed that the electrochemical behavior is most markedly affected by the morphological characteristics than by the chemical composition of the anodized layers. By the SECM analysis it was observed that there was a significant reduction of the local current value of the active regions of the polished condition compared to the anodized condition. Moreover, the fatigue behavior of the samples in the polished condition in the air it showed a fatigue strength at the stress levels close to 155 MPa to 106 cycles.
MEMBROS DA BANCA:
Presidente - Interno ao Programa - 1671298 - RENATO ALTOBELLI ANTUNES
Membro Titular - Examinador(a) Interno ao Programa - 1671292 - SYDNEY FERREIRA SANTOS
Membro Titular - Examinador(a) Externo ao Programa - 1646041 - CARLOS TRIVENO RIOS
Membro Titular - Examinador(a) Externo ao Programa - 1925199 - ANIBAL DE ANDRADE MENDES FILHO
Membro Titular - Examinador(a) Externo à Instituição - IDALINA VIEIRA AOKI - USP
Membro Suplente - Examinador(a) Interno ao Programa - 1671394 - HUMBERTO NAOYUKI YOSHIMURA
Membro Suplente - Examinador(a) Externo ao Programa - 2604737 - EVERALDO CARLOS VENANCIO
Membro Suplente - Examinador(a) Externo ao Programa - 3068039 - MOHAMMAD MASOUMI
Membro Suplente - Examinador(a) Externo à Instituição - NELSON BATISTA DE LIMA - IPEN