CECILIA CHAVES GUEDES E SILVA

CECILIA CHAVES GUEDES E SILVA

(Fonte: Lattes)

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Possui graduação em Engenharia de Materiais pela Universidade Presbiteriana Mackenzie (1997), mestrado em Tecnologia Nuclear Aplicações pelo Instituto de Pesquisas Energéticas e Nucleares (2000) e doutorado em Tecnologia Nuclear Materiais pelo Instituto de Pesquisas Energéticas e Nucleares (2005). Atualmente é pesquisador do Instituto de Pesquisas Energéticas e Nucleares. Tem experiência na área de Engenharia de Materiais, atuando principalmente nos seguintes temas: materiais cerâmicos, biomateriais e materiais nucleares. (Texto extraído do Currículo Lattes em 08 out. 2021)

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Oxidation behavior of Si3N4-TiN composites at 1400 ºC
2023 - FERREIRA, T.S.; CARVALHO, F.M.S.; GUEDES-SILVA, C.C.
In this paper, the oxidation behavior of silicon nitride with different contents of TiN was evaluated at 1400 oC for 64 hours in air. The oxidized samples were characterized by X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy. Weight gain measurements have shown that the oxidation followed a multiple-law model with linear, parabolic, and logarithmic contributions. The samples presented high weight gain at the beginning of the process followed by the formation of an amorphous silica surface layer containing Y2Ti2O7 and rutile crystals. Cracks and holes were detected on the oxide layer. The oxidation resistance of the composites was strongly influenced by the initial content of TiN.
Microstructure, mechanical properties and in vitro biological behavior of silicon nitride ceramics
2018 - GUEDES-SILVA, CECILIA C.; RODAS, ANDREA C.D.; SILVA, ANTONIO C.; RIBEIRO, CHRISTIANE; CARVALHO, FLAVIO M. de S.; HIGA, OLGA Z.; FERREIRA, THIAGO dos S.
The bioinert surface of silicon nitride ceramics led us to investigate the additions of SiO2, CaO and Al2O3 in order to aid the liquid phase sintering and improve the mechanical properties and biological behavior of the final materials. The sintered materials reached ca. 97% of theoretical density and total α→β-Si3N4 transformation. The samples had relatively high values of fracture toughness while their elastic modulus values were lower than those of conventional silicon nitride ceramics. Apatite deposits were observed on the surfaces analyzed after SBF (simulated body fluid) immersions, suggesting their bioactivity. Osteoblasts proliferation and calcified matrix were also detected as response to cells/ materials contact. This combination of properties suggests that all studied compositions are promising for applications in biomedical devices. Moreover, compositions with alumina additions and higher silica content had better in vitro biological behavior, densification and mechanical properties, suggesting greater potential to be used in bone substitute devices.
Influence of alumina phases on the molybdenum adsorption capacity and chemical stability for 99Mo/99mTc generators columns
2016 - GUEDES-SILVA, C.C.; FERREIRA, THIAGO dos S.; CARVALHO, FLAVIO, M.S.; PAULA, CAROLINA M. de; OTUBO, LARISSA
Technetium-99m is the clinically most used radionuclide worldwide. Although many techniques can be applied to separate 99Mo and 99mTc, the most commonly used method is the column chromatography with alumina as stationary phase. However, the alumina nowadays used has limited adsorption capacity of molybdate ions which implies the need to develop or improve materials to produce high specific activity generators. In this paper, alumina was obtained by a solid state method and heat treatments at different conditions. The powders had a microstructure with porous particles of γ, δ, θ and α-Al2O3 phases as well as specific surface area between 36 and 312 m2 g-1. Most interesting results were reached by powders calcined at 900oC for 5 hours which had high chemical stability and a molybdenum adsorption capacity of 92.45 mg Mo per g alumina.
Formation of aluminium titanate with small additions of MgO and SiOsub(2)
2016 - GUEDES SILVA, CECILIA C.; CARVALHO, FLAVIO M. de S.; FERREIRA, THIAGO dos S.; GENOVA, LUIS A.
Hydroxyapatite coating on silicon nitride surfaces using the biomimetic method
2008 - GUEDES e SILVA, CECILIA C.; RIGO, ELIANA C. da S.; MARCHI, JULIANA; BRESSIANI, ANA H. de A.; BRESSIANI, JOSE C.
Influence of additive system (aLSUB(2)oSUB(3)-reSUB(2)oSUB(3), re=y,lA,nD.dY,yB) on microstructure and mechanical properties of silicon nitride-based ceramics
2009 - MARCHI, JULIANA; GUEDES e SILVA, CECILIA C.; SILVA, BRUNO B.; BRESSIANI, JOSE C.; BRESSIANI, ANA H. de A.