Fabrication of AlON transparent ceramics with Si₃N₄ sintering additive

In this paper, Si3N4 was used as a novel solid-state sintering additive to prepare AlON transparent ceramics with high transparency and flexural strength via the pressureless pre-sintering and hot isostatic pressing (HIP) method at a relatively low HIP temperature (1800 degrees C). The effect of Si3N4 content on the phase, microstructure, optical property, and flexural strength was investigated. The experimental results showed that a Si element was homogenously distributed in both pre-sintered and HIPed AlON ceramics. The densification enhanced, the grain grew with the increasing Si3N4 content in the pre-sintered AlON ceramics, and all the samples became pore-free after HIP, which favor transparency. The AlON ceramics doped with 0.10 wt% Si3N4 had the highest transmittance of 83.8% at 600 nm and 85.6% at 2000 nm (4 mm in thickness), with flexural strength of 404 MPa, which were higher than those of the previous reports.