Microstructure study of alumina ceramics from powder mixtures of nano and microsized particles

In this work, was proposed to produce nanosized alpha-Al2O3 powder from precipitation reactions, in order to reduce the alumina ceramics sintering temperature. For this an addition of nanosized powder in the commercial microsized powders was done. The nano and microsized powder particle mixtures were obtained by precipitation of nanosized aluminum hydroxide in microsized Al2O3 in liquid suspension. Several compositions of nano and microsized powders were carried out. These powder compositions were based on data of simulated particle packing. The nano and microsized powder mixtures was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and thermogravimetric and differential thermal analysis (TGA and DTG). The powder mixtures were compacted by uniaxial (75MPa) and isostatic (300MPa) pressing, producing cylindrical samples. The powder compacted samples were sintered at 1400 degrees C. Sintered ceramics were characterized by XRD and SEM. The results showed that the higher density of sintered ceramic was obtained for 65% of microsized powder and 35% of nanosized powder mixture. This composition of size of particles of the powder was in agreement with the theoretical simulation.