Overcoming transparency limitations in 3D-printed yttria ceramics

Microstructure and surface roughness are two critical factors governing the transparency of transparent ceramics. The manufacturing mechanism of additive manufacturing (AM) layer by layer is destined that the layer thickness has an important influence on the microstructure and surface quality of the printed workpiece. Simultaneously, the occurrence of the stair-stepping phenomenon unavoidably results in a significant surface roughness. Therefore, in this study, yttria (Y2 O3 ) transparent ceramics with different printing layer thicknesses were fabricated by AM to investigate the effect of layer thickness on its optical and mechanical properties. The findings indicate that an increase in the layer thickness correlates with a heightened density in the printed green bodies, subsequently leading to enhanced transmittance in the final sintered body. When the layer thickness approximates or falls below the size of large particle agglomerations found in ceramic powders, numerous pores, and voids emerge within the green bodies. Significantly, at a layer thickness of 45 mu m, the in-line transmittance of Y2 O3 can reach up to 97.73 % of the theoretical limit. In addition, the surface roughness of the Y2 O3 ceramics decreased as the layer thickness increased. To facilitate the further transition from translucent to transparent 3D Y2 O3 structures, a vibration-assisted chemical-mechanical polishing technique was developed by replacing water with a colloidal SiO2 suspension. This technique resulted in a significant reduction in the surface roughness of the Y2 O3 ceramics by 95.42 % and eliminated the stair-stepping phenomenon caused by AM, thus increasing 66.12 % of the in-line transmittance. These enhancements expand their potential applications in laser amplification, optical communications, and other areas requiring high-transparency materials. The method developed in this study can be used for the AM-based fabrication of transparent 3D polycrystalline ceramics. (c) 2025 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & ( http://creativecommons.org/licenses/by-nc-nd/4.0/ )