A HYDROTHERMAL ROUTE FOR PRODUCTION OF DENSE, NANOSTRUCTURED Y-TZP

Y-TZP powders were prepared either by calcination in air or crystalliz ation under hydrothermal conditions of a hydrous gel, obtained by copr ecipitation. Differences in powder properties, green compact structure and sinterability were examined. Crystallization under hydrothermal c onditions occurs at temperatures as low as 190 degrees C in the presen ce of ammonia. The hydrothermally treated powders are composed of soft agglomerates, that collapse under very low pressures, resulting in gr een bodies with high densities and small pore radii. The sinterability is greatly improved by the hydrothermal treatment and allowed the pro duction of dense, nanostructured Y-TZP by free sintering at 1050 degre es C.