Fluorescent MIL-53(Al) Enhanced 3D Printing of Si3N4 Ceramics via Vat Photopolymerization

Vat photopolymerization (VPP) has recently been applied to fabricate silicon nitride (Si 3 N 4 ) ceramics. To overcome limitations in Si 3 N 4 slurry curing performance, a multi-functional modification strategy utilizing the metal-organic framework MIL-53(Al) was proposed. The introduction of MIL-53(Al) simultaneously affects slurry photocuring performance and ceramic microstructural regulation. MIL-53(Al) serves as a fluorescent active filler acting as an in situ photon source under ultraviolet irradiation, thereby enhancing the curing depth by an average of 17.5 µm. During the debinding process, the decomposition of MIL-53(Al) leaves a pore structure and aluminum oxide that can assist sintering, facilitating phase transformation and forming a well-interlocked β-Si 3 N 4 microstructure. The sintered Si 3 N 4 ceramic exhibited a flexural strength of 269.2  ±  12.6 MPa, and a fracture toughness of 3.54 ± 0.21 MPa·m 1/2 at a porosity of 23.9%. This study demonstrates the multi-functional role of MOF-based additives for both enhancing slurry printability and tailoring ceramic microstructure in fabrication of porous Si 3 N 4 ceramics via VPP.