LUCAS APARECIDO DOS SANTOS FERREIRA
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Artigo IPEN-doc 29908 Mechanical and electrical characterization of 8YSZ-ScCeSZ ceramics2023 - FUJIMOTO, T.G.; SERIACOPI, V.; FERREIRA, L.A.S.; MACHADO, I.F.; MUCCILLO, E.N.S.The effects of small amounts (up to 5 wt.%) of scandia- and ceria-stabilized zirconia on the electrical conductivity, and the elastic modulus and hardness of yttria-stabilized zirconia were investigated by impedance spectroscopy and nanoindentation tests, respectively. The main purpose of this work was to obtain solid electrolyte compounds with improved properties compared to those of the base materials. Solid electrolytes compounds were prepared by solid-state reaction synthesis with sintering at 1450 ºC for 4 h. All prepared compounds exhibit a cubic fluorite-type structure. The microstructure of the compounds consists of polygonal grains with low (< 2%) porosity. The mean grain size estimated by the intercept method was 5 ± 1 μm. The electrical conductivity of the compound ceramics is lower than that of the base material. Addition of scandia-stabilized zirconia is found to exert a beneficial effect on the matrix by increasing the elastic modulus, achieving 221 MPa for 5 wt.% of the additive.Artigo IPEN-doc 28341 Influence of the sintering method on densification, microstructure and electrical conductivity of 12Ce-TZP2021 - FERREIRA, L.A.S.; MUCCILLO, E.N.S.Zirconia containing 12 mol-% cerium oxide ceramics were prepared by solid state reaction utilising the conventional, fast firing and two-step sintering methods. The sintering temperature and time were varied aiming to determine ideal sintering profile for these methods. The monoclinic and tetragonal phase contents, microstructure and electrical conductivity of dense specimens were investigated. The linear shrinkage was found negligible up to 1100°C and the maximum rate of shrinkage was achieved at 1150°C. Densification increased up to 2 h for conventional sintered specimens. Stabilisation of tetragonal phase in non-isothermally sintered specimens occurred at a high temperature (1500°C). Specimens sintered by the two-step method attained high density along with small grain sizes. Optimised sintering profiles were determined for all the sintering methods used.