Hot isostatic pressing of transparent AlON ceramics assisted by dissolution of gas inclusions

In this paper, highly transparent AlON ceramics were fabricated using hot isostatic pressing (HIP) assisted by dissolution of gas inclusions. The influence of additive content, pre-sintering, HIPing and annealing parameters on the sintered AlON ceramics were investigated and optimized. The obtained transparent AlON ceramics kept high transmittance 85.8 % and low loss coefficient 0.005 cm−1 at 2000 nm after annealing. Compared with different sintering additives and pre-sintering atmospheres, densification mechanism of the present material is revealed that SiO was formed from SiO2 during pre-sintering under N2 atmosphere occupying micropores which was then solidified and dissolved into AlON matrix in HIPing processing. This transformation and dissolution of gas into AlON ceramics make it possible to anneal the HIPed ceramics without degradation of microstructure and transmittance.