Síntese e caracterização dos compósitos metal-cerâmicos: AISI 316l/smba2cu3o7-δ e al/smba2cu3o7-δ

• Ano de defesa: 2023
• Autor(a) principal: Nunes, Lumena Glória de Souza
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal do Espírito Santo; BR; Doutorado em Engenharia Mecânica; Centro Tecnológico; UFES; Programa de Pós-Graduação em Engenharia Mecânica
• Palavras-chave em Português: Sinterização; Supercondutividade; Material cerâmico; subject.br-rjbn; Engenharia Mecânica
• Link de acesso: http://repositorio.ufes.br/handle/10/16813

The electrical, mechanical, and magnetic properties of superconducting ceramics have been investigated targeting technological applications. However, there are still technological challenges to be solved to enable its use on a large scale. Considering this scenario, in order to increase the mechanical properties of the bulk superconducting ceramic SmBa2Cu3O7- δ, a series of composites of stainless steel (100-x) AISI 316L + x SmBa2Cu3O7-δ and (100-x) SmBa2Cu3O7-δ + x Al were prepared by solid state reaction method. The (100-x) AISI 316L + x SmBa2Cu3O7-δ samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (MEV), hardness and magnetic susceptibility measurements. The microstructural analysis indicated the formation stainless steel with the presence of superconducting ceramics along their grain boundaries. Samples prepared without post-oxygenation, in the bulk form, presented ac magnetic susceptibility signal with superconducting transition at Tc ≈ 90K. Samples of (100-x) SmBa2Cu3O7-δ + x Al composites were also prepared by the solid-state reaction method. All samples were characterized by X-ray diffraction, magnetic susceptibility, scanning electron microscopy, relative density, and Vickers microhardness measurements. The results of microstructural analysis indicated that the addition of Al particles did not alter the crystal structure of the Sm-123 phase. Furthermore, ac magnetic susceptibility measurements of the samples revealed that the onset of the transition to the superconducting state of the composites are Tc ≈ 92K. However, the superconducting transitions of the composite samples showed a broadening as a result of the proximity and disorder effect. Energy dispersive spectrometry (EDS) analysis and elemental distribution maps of the composite samples indicated that Al nanoparticles precipitated at the grain boundaries of Sm123 ceramics. Finally, the Vickers microhardness values decreased with the addition of Al. These results demonstrate that the stainless steel and aluminum addition has improved the toughness of Sm-123 ceramic and it did not affect their superconducting properties.