Highly transparent AlON sintered from powder synthesized by direct nitridation

Transparent AlON ceramic was pressurelessly sintered from powder synthesized by direct nitridation of Al–Al2O3 starting mixtures. TG, SEM and XRD analyses were conducted to investigate the detail procedure of direct nitridation. The Al spheres were dispersed by submicron Al2O3, then nitrided and reacted with Al2O3 to form AlON. The particle size of AlON is about 10–30 μm with irregular morphology. With the aid of ball milling and sintering additives, 2 mm thick AlON ceramic with in-line transmittance of 80.6% at 1100 nm and above 77.1% at 400 nm was obtained successfully, demonstrating that the direct nitridation method is another promising approach for the preparation of AlON ceramics with high transparency.