Additive Manufacturing of Mullite Materials Based on Core‐Shell Alumina Nanoparticles

Mullite materials exhibit great significance because of thermal shock resistance and high‐temperature creep resistance, but the performance of 3D‐printed mullite materials is still not satisfactory due to the unavailability of mullite nanopowders and the limitations of 3D printing technologies. This work employed a strategy that utilizes core‐shell nanoparticles (alumina core/organosilicon oligomer shell) to enable vat photopolymerization 3D printing of hybrid organic–inorganic materials, followed by thermochemical conversion into high‐performance mullite materials. On one side, the organosilicon oligomer shell endowed photosensitive slurries with low viscosity (11.7–101.6 Pa·s), high photocuring activity (critical energy: 8.3–12.7 mJ/cm 2 ; penetration depth: 50.1–60.1 µm), and good compatibility with the resin matrix. On the other side, the shell can be transformed in situ into the component of mullite materials during the sintering process, together with alumina nanoparticles. Through optimizing the microscopic composition and structure, the flexural strength of mullite materials reached 257.7 MPa. This work provides a new route for vat photopolymerization 3D printing of mullite materials through the innovative adoption of core‐shell structured nanopowders.