Regulation of interlayer structure and grain anisotropy in DLP 3D-printed alumina ceramics by the plasticizer PEG200

Achieving both high forming accuracy and high mechanical strength is a fundamental challenge in DLP-printed alumina ceramics, as solid loading has opposite effects on these two requirements. Plasticizer offers an effective technical solution to this challenge, but their regulatory effects on interlayer bonding and anisotropic grain growth in DLP-printed ceramics are rarely investigated systematically. In this study, PEG200 was used as the plasticizer to investigate its effects on the slurry properties, microstructure, and mechanical properties of DLP-printed alumina ceramics. Based on the optimal formulation, the influence of debinding atmosphere on the microstructure and properties was further investigated. The results showed that an appropriate 6 wt% PEG200 improved powder dispersion uniformity and significantly suppressed the interlayer stair-step effect. With PEG200 content from 0 to 6 wt%, the side surface roughness decreased from 10.601 μm to 5.590 μm, a reduction of 47.3%. Meanwhile, PEG200 promoted equiaxed grain growth, with the grain aspect ratio decreasing from 1.817 to 1.658 and circularity increasing from 0.820 to 0.848, which further improved the flexural strength by 39.4%, from 320.10 MPa to 446.33 MPa. After debinding in an argon atmosphere, the flexural strength further increased to 609.26 MPa, with a relative density of 99.16%. This study demonstrates that an appropriate amount of PEG200 achieves synergistic optimization from microstructure to macroscopic properties by improving interlayer structure and promoting equiaxed grain growth, providing an effective strategy for fabricating high-performance DLP 3D-printed alumina ceramics.