Preparation of spherical AlON powder and high transparent ceramics by pressureless sintering

Abstract The sphericity and fluidity of the powder play a crucial role in the forming and sintering of ceramics. High‐performance AlON spherical powder was prepared for the first time by spray drying of powder fired by solid‐phase reaction, and the preparation of AlON transparent ceramics was realized under pressureless sintering conditions. The effect of AlN dosage on the purity of AlON powder was investigated, and the powder fluidity was improved by spray drying technique. Then the best spray drying process was selected by scanning electron microscopy, AD/TD, green density, MIP and transmittance measurements. The AlON particles obtained under the optimal granulation process have good dispersibility, high green density after pressing, and uniform pore distribution. After dry pressing and sintering at 1900°C for 20 h, the AlON ceramics with linear transmissivity of 84.3% at 2 μm wavelength can be obtained. The excellent pressing and sintering properties of AlON granulated particles make it possible for large‐scale production.