Fabrication of Highly Transparent AlON Ceramics via Tape Casting

Transparent aluminum oxynitride (AlON) ceramics are highly desirable for laser transmission and photodetector-related applications, benefiting from their superior transparency, excellent mechanical properties, and stable dielectric performance. However, large-scale, cost-effective manufacturing of high-quality transparent AlON components remains a significant challenge, mainly due to difficulties in forming defect-free green bodies and achieving full densification without residual pores. In this study, we address these challenges by employing a non-aqueous tape casting process using high-purity AlON powder synthesized via carbothermal reduction. Here, the dense, uniform, and free of delamination tapes were processed via hot pressing followed by pressureless sintering to achieve full densification. Systematic investigation of the sintering holding time revealed that, with the extension of the holding time, the interior of the ceramic tend to become dense, the crystal regions become complete, and defects such as pores that could absorb and scatter light were reduced, thus improving the optical transmittance. With the optimized sintering parameters, we successfully fabricated AlON ceramics with a transmittance of 80.2% in the 200-1400 nm range, a bending strength of 343 MPa, and a hardness of 18.5 GPa. This approach successfully produced transparent AlON ceramics with high density and excellent optical properties, thus offering critical technical support for their large-scale application in laser, optical storage, and photodetector fields.