Affiliation:
1. Instituto de Tecnología de Materiales (ITM), Universitat Politècnica de València, Camino de Vera, s/n, Valencia, Spain
Abstract
Homogeneous Al2O3-Zr0.91Y0.09O1.955 (65-35mol%) nanopowders have been
prepared in a wide temperature range (from 1073 to 1573K) by thermal
decomposition of amorphous precursors, made previously by freeze-drying of
appropriate solutions in air. Electron microscopy images show that, whereas
at low temperatures (973 K) pseudo-spherical particles constituted of Al2O3
and Zr0.91Y0.09O1.955 grains are observed (~38 nm), at high temperatures
(1573 K) a homogeneous dispersion of nanocrystalline ZrO2-based grains (~186
nm) is dispersed in the sintered Al2O3 matrix. The comparison between phase
and microstructure evolution in these samples clearly indicates that the
disorder at the atomic scale in the precursor makes the attainment of higher
temperatures necessary for nucleation and growth of both phases. Finally, a
selected material was sintered in a mono-mode microwave device at 2.45GHz in
air at 1573 and 1673K. This fast-microwave technology allows fabrication of
composites with high densities (~99%TD) and excellent mechanical properties,
such as hardness and Young?s modulus reaching 25.6GPa and 358GPa,
respectively.
Publisher
National Library of Serbia