INVESTIGADORES
CAMERUCCI Maria andrea
congresos y reuniones científicas
Título:
Elastic properties and thermal conductivity of oxide- and silicate-based high-temperature engineering ceramics
Autor/es:
W. PABST; E. GREGOROVÁ; A. MUSILOVÁ; T. UHLÍřOVÁ,; Z. SOFER; O. JANKOVSKÝ; M. A. CAMERUCCI; M. L. SANDOVAL; M. H. TALOU
Lugar:
Prague
Reunión:
Conferencia; HITHERM; 2013
Resumen:
Elastic properties and thermal conductivity are
among the most important basic properties that must be reliably known not only for
assessing the room temperature behavior and insulation capability but also the high-temperature
performance and thermal shock resistance of high-temperature engineering
ceramics and refractories. This contribution reports on some of our results ?
theoretical calculations as well as experimental measurements ? concerning
oxides (alumina, zirconia, silica), two-phase composites (alumina-ziconia) and multiphase
silicate-based ceramics (cordierite ceramics as well as kaolin-mullite- and
mullite-alumina based ceramics). The dependence of the elastic moduli and thermal
conductivity on phase composition (volume fractions of solid phases), porosity
(volume fractions of pores) and temperature are discussed for these materials.
It is shown that the so-called one-point bounds (Voigt-Reuss or Wiener bounds)
are generally useful for the estimation of multiphase composites, and that
two-phase modeling, which offers additional tools for predicting effective
properties (Hashin-Shtrikman bounds, sigmoidal averages), can be used in many
cases even for multiphase materials (with hierarchical microstructure). With
regard to porosity it is shown that for all materials investigated so far ?
except for highly porous cellular ceramics (with more
than 70 % porosity) ? our exponential relation
provides more realistic predictions for the effective Young?s modulus and
thermal conductivity of porous ceramics than the commonly used power-law
relations. However, partially sintered materials are shown to lie below this
prediction. Concerning the temperature dependence of elastic moduli it is shown
that ? in contrast to widespread belief ? not all ceramics used in
high-temperature applications exhibit a decrease of the Young?s modulus with
temperature and that many of them exhibit hysteresis effects and other elastic
anomalies.