Enhanced high-temperature dimensional accuracy by fibers in silica ceramic cores prepared through vat photopolymerization 3D printing

3D printing technology provides new ways to complex-shaped ceramic cores forming inner structures in aero-engine blades, but its high-temperature dimensional accuracy is highly impacted by their volume shrinkage and creep deformation. Silica ceramic cores reinforced by mullite fibers were fabricated by 3D printing in terms of vat photopolymerization in this work. Due to the scraper paving the ceramic slurry in 3D printing, majority of the mullite fibers displayed orientation distribution inside the printing layers and decreased the bending strength as the fiber content was below 5 wt.%. With 12.5 wt.% of mullite fibers, some fibers showed disorder distribution and arranged to connect the interlayer cracks, therefore improving the strength by fiber pull-out. Even though the reinforcement effect of mullite fibers was inadequate, the porosity and leaching rate were significantly improved. Furthermore, the mullite fibers were beneficial to lower shrinkage during sintering and casting, and enhanced the creep resistance due to the high softening temperature, which resulted in enhanced dimensional accuracy.