Nanostructured Y2O3 ceramics elaborated by Spark Plasma Sintering of nanopowder synthesized by PEG assisted combustion method: The influence of precursor morphological characteristics

Abstract

Dense yttria ceramics were prepared by Spark Plasma Sintering of a nanopowder synthesized using a PEG assisted combustion method. Densification occurs between 800 degrees C and 900 degrees C without any additive. This corresponds to one of the lowest sintering temperature found in the literature for Y2O3. Because of a significant release of organic species, the Y2O3 precursors obtained by this synthesis route contains macropores that have a negative impact on the final microstructure. We show that the emergence of these macropores can be minimized by decreasing the annealing temperature used for the precursor powder (in a temperature range of 300-650 degrees C) as opposed to the usual 800 degrees C. Finally, a precursor annealed at 650 degrees C allows us to obtain fully dense ceramics, with a very fine and homogeneous microstructure (and a grain size around 300 nm). Vickers microhardness and fracture toughness were measured and discussed in relation to the microstructure of the ceramics.