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:
PABST W.; GREGOROVÁ E; UHLÍOVÁ T.; CAMERUCCI M. A; TOMBA-MARTINEZ A. G; SANDOVAL M. L; TALOU M. H.; SOFER Z.,; JANKOVSKÝ O
Reunión:
Conferencia; REFRA & HITHERM; 2014
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), 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 Young?s 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 (Wiener-Paul 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 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 not all ceramics used in high-temperature
applications exhibit a decrease of Young?s modulus with temperature and that
some of them exhibit hysteresis effects and other elastic anomalies.