Sintering of Alumina Powders Obtained by a Pechini-Type Method with Addition of Seeds

Abstract

Alumina ceramics are used in many areas of modern industry because of their excellent mechanical, thermal and optical properties. Sintering of alumina usually requires high temperatures (> 1600°C), due to the large and extensive pore network developed during the reconstructive transformation to its stable alpha phase. Consequently, it is very difficult to suppress grain growth during sintering. In this work it was studied the sintering behavior of alumina powders obtained through a modified Pechini-type method, with addition of seeds of calcined alpha-alumina. Powders without addition of seeds were synthesized for comparison. After calcinations at the temperature of 1000°C, the powders were uniaxially pressed. The compacts were sintered in air in the range of 1400-1600°C and characterized by density and porosity measurements, scanning electron microscopy, X-ray diffraction and infrared spectroscopy. The behavior in the sintering of the compacts with addition of seeds was clearly different compared with the compacts with no seeds.