Study on robust additive of CaCO₃ for fast fabrication of highly transparent AlON ceramics by pressureless sintering

Abstract

Fabrication of transparent AlON ceramics is extra sensitive to both particle size of starting powder and sintering additive due to shuttling transformation between AlON and Al2O3 + AlN during heating. One possible solution is to select robust additive to suppress the shuttling transformation. In this work, three AlON powders with different median particle sizes of 0.6, 0.9, and 1.1 μm were prepared. After studying the effect of CaCO3 on densification process, AlON ceramics with the maximum transmittance of ≥81.1% were successfully fast prepared by pressureless sintering (PS) at 1880°C for only 2.5 h by using three AlON powders doped with different CaCO3 amount. Specifically, AlON ceramics prepared from 1.1 μm with 0.5–0.8 wt.% CaCO3 doping consistently showed the maximum transmittance of ≥85.3%, which indicates that CaCO3 can serve as a robust additive to enable fast fabrication of highly transparent AlON ceramics even by PS.