Cold isostatic and explosive isodynamic compaction of Y-TZP nanoparticles

Yttria-doped zirconia compacts (2.5 mol%) of spray-pyrolysed powders were prepared by two routes: cold isostatic pressing (CIP) and explosive isodynamic compaction (EXIC). Starting powders of 6 nm mean primary crystallite size are tetragonal single-phased with good homogeneity in chemical composition and with a narrow crystallite size distribution. This paper reports on a comparative study of the microstructure of these pellets in terms of grain size and density. CIP and sintering at 1500 °C led to nanocrystalline ceramics consisting of an average primary grain size of 60 nm and characterized by a density of 96% of the theoretical value with an unimodal distribution of 300 nm average aggregate size. Ceramics with 6 nm average grain size were successfully obtained by EXIC but with densities as low as 65% of the theoretical one. Both ceramics were still tetragonal single-phased, characterized by a good purity: only 0.1 wt.% Si and some traces of Hf.