Densification Behavior of Zirconia Ceramics Sintered Using High-Frequency Microwaves

Abstract

The aim of the investigation was the formation of zirconia ceramics with a fine-grained microstructure and low porosity. The potential of high frequency (30 GHz) microwave sintering in this field was studied. The application of microwaves allowed high heating rates and short processing times because of volumetric heating and enhanced sintering kinetics and thereby a better control of the microstructure. Green bodies were made of tetragonal (8 mol-% Y2O3) and cubic (10 mol-% Y2O3) nanoscale and submicron zirconia powders, dispersed in aqueous suspensions. They were prepared by electrophoretic deposition (EPD) and had relatively high green densities and a homogenous pore size distribution. Green bodies and ceramics were characterized by means of XRD, SEM, density measurements by means of the Archimedes method and Hg-porosimetry. The main focus of this work is on the investigation of grain size evolution as a function of density.