Reaction Sintering of Transparent Aluminum Oxynitride (AlON) Ceramics Using MgO and Y₂O₃ as Co-Additives

Abstract

Transparent aluminum oxynitride (AlON) ceramics have been prepared through a method based on direct reaction sintering of alumina and aluminum nitride powders using MgO and Y2O3 as co-additives. The sintering additives could cause the formation of liquid phase during sintering, which would greatly promote the densification and eliminate pores. The grain size of AlON is about 50-100μm. The influence of different component of Al2O3 and AlN as well as sintering temperature on microstructure and optical properties of AlON have been studied. High transparent AlON ceramics with the in-line transmittance of 80.3% at 2000 nm wavelength have been prepared when the concentration of sintering additives was 0.16wt% Y2O3 and 0.02wt% MgO.

Reactive sintered highly transparent AlON ceramics with Y2O3‐MgAl2O4‐H3BO3 ternary additive

“…The trend shown by these parameters was similar to that shown by the transmittance of the ceramics (Figure 3(A)). To our surprise, the ceramic doped with 0.1 wt.% Y 2 O 3 ‐0.4 wt.% MgAl 2 O 4 ‐0.12 wt.% H 3 BO 3 showed a haze as low as 3.46% and an in‐line transmittance of up to 81% at 600 nm, which is much higher than those of the reactive sintered AlON ceramics previously reported 7‐9 . A comparison of the optical performance of the one‐step reactive sintered ceramics prepared in this study with those of the previously reported data (Figure 3(B)) revealed that a breakthrough in this study has been achieved in terms of the thickness and transmittance.…”

“…(A) Transmittance of the AlON ceramics with 0.1 wt.% Y 2 O 3 ‐0.4 wt.% MgAl 2 O 4 ‐ x wt.%H 3 BO 3 ; (B) comparison of the transmittance of the AlON ceramics prepared by one‐step reactive sintering 7‐9 [Color figure can be viewed at wileyonlinelibrary.com]…”

“…Generally, choosing suitable additives is an efficient approach for improving the densification behavior to obtain high optical‐quality AlON ceramic. Y 2 O 3 , La 2 O 3 , MgO, and BN are the commonly used additives 4,6‐9 . Gentilman et al 6 reported a polycrystalline AlON ceramic with a density higher than 99% of its theoretical density by using BN and Y 2 O 3 as additives, but no transmittance data.…”

“…Yuan et al 8 demonstrated that the co‐addition of MgO and Y 2 O 3 was more efficient for enhancing the densification of AlON ceramics than the addition of MgO or Y 2 O 3 separately, and a total transmission of 60% was achieved for the 1‐mm‐thick‐polished sample doped with MgO‐Y 2 O 3 . The transmittance of AlON ceramics fabricated by reactive sintering was remarkably enhanced to approximately 70% at 600 nm (2‐mm thick) by further optimizing the MgO‐Y 2 O 3 dosage 9 . Besides, 4,10,11 the influence of sintering procedure on the transmittance of AlON ceramics was also investigated.…”

Effects of sintering aids on microstructure, mechanical, and optical properties of AlON ceramics synthesized by SPS

“…Moreover, the addition of sintering aids, which are rare‐earth metallic oxides, such as Y 2 O 3 /La 2 O 3 , and alkaline earth metallic oxides, such as MgO, is an important factor that affects the properties of AlON ceramics 14–18 . However, a single type of sintering aid is insufficient to meet the performance requirements of AlON ceramics; therefore, composite sintering aids have become popular.…”