CECILIA CHAVES GUEDES E SILVA

CECILIA CHAVES GUEDES E SILVA

(Fonte: Lattes)

ORCID

ScopusID

ResearcherID

Resumo

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)

Página do item completo

Resultados de Busca

Agora exibindo 1 - 4 de 4

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.
Silicon nitride with titania, calcia and silica additives for orthopaedic applications
2020 - GUEDES-SILVA, CECILIA C.; RODAS, ANDREA C.D.; CARVALHO, FLAVIO M.S.; HIGA, OLGA Z.; FERREIRA, THIAGO S.
Titanium, silicon and calcium ions have demonstrated positive effects in bone healing. Therefore, this paper investigates the densification, mechanical properties and in vitro biological behaviour of TiO2, together with SiO2 and CaO, on silicon nitride ceramics to be used in clinical applications. The results revealed that the sintered samples reached high values of relative density and fracture toughness, non-cytotoxicity as well as good ability to promote cell proliferation and form a layer of carbonated hydroxyapatite on their surfaces, after immersion in simulated body fluid. The sample with the highest amount of TiO2 reached the highest value of relative density and the best results of cell proliferation and fracture toughness, indicating the great potential to be explored by in vivo experiments for later application as intervertebral devices.
Densification and microstructure of Si3N4-TiN ceramic composites
2019 - FERREIRA, T.S.; CARVALHO, F.M.S.; GUEDES-SILVA, C.C.
Silicon nitride is a ceramic material widely used in various structural applications at high temperatures owing to its excellent combination of mechanical and thermal properties. To increase the application of Si3N4, many researches have been developed to improve its fracture toughness and processing conditions. In this study, the sintering and microstructure of Si3N4-TiN composites, containing Al2O3 and Y2O3 as sintering aids, were studied. Samples were obtained by the conventional method of mixing powders and sintered at 1750 ºC/1 h and 1815 ºC/1 h under nitrogen atmosphere. Density values of the samples were determined by the Archimedes method, reaching values between 96.9% and 98.0% of theoretical density, with a porosity of less than 0.5%. The sintered samples were analyzed by X-ray powder diffraction and scanning electron microscopy. The results showed the materials reached high fracture toughness, low hardness and a microstructure with TiN grains dispersed in a β-Si3N4 matrix containing an amorphous intergranular phase.
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.