Sinterização diferencial e auto-tensionamento: efeitos na condutividade elétrica da Zircônia estabilizada com Ítria
Abstract
Recent researches indicate the possibility of increasing Yttria Stabilized
Zirconia (YSZ) electrical conductivity by generating stress states in the material,
by applying external loads or by its insertion in multilayer systems. On the other
hand, in the past decades, several papers have shown that the formation of
defects and the incomplete densification in ceramic composites containing rigid
inclusions are related to the emergence of stresses in the matrix due to the
phenomena of restricted and differential sintering. In this work, these
phenomena were induced in 8 mol% Yttria Stabilized Zirconia (8YSZ) matrices
by means of controlled addition of different contents of rigid inclusions of
sintered ceramic particles with different shapes (spherical and jagged), sizes
(60-200 µm) and compositions (8YSZ, 3YSZ and alumina). The effects of
residual stresses after sintering on the electrical conductivity of 8YSZ were
evaluated and, under specific conditions, the addition of 1 vol% of YSZ irregular
rigid inclusions led to an increase of 36% in total electrical conductivity
compared to samples without inclusions. Computer simulations provided
additional information on the development and evolution of stresses during
sintering.
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