Effect of vacuum infiltration time on the properties of silica-based ceramic cores prepared by selective laser sintering combined with vacuum infiltration

Selective laser sintering (SLS) for fabricating silica (SiO₂) ceramic cores can overcome the bottleneck of mold constraints faced by traditional methods in aerospace casting. However, it still suffers from issues such as a low packing density of SiO₂ ceramic green bodies and poor mechanical properties after sintering. To address this, this work combines SLS with the vacuum infiltration (VI) process, with a focus on investigating the influence mechanism of VI time on the structure and properties of SiO₂ ceramics. The results show that nanosilica sol infiltrates rapidly under the action of the Al₂O₃ infiltration aid, and with increasing VI time, the growth rate of the dense layer thickness on the outer surface of the green body first increases but then decreases. SEM and XRD results indicate that the interlayer delamination and pores of the green body are gradually improved, and the diffraction peaks of cristobalite in the ceramics are significantly enhanced. When the VI time is 40 min, the infiltration thickness reaches 607 μm, and the comprehensive properties of the ceramics are optimized. At this point, the infiltration weight gain rate and axial shrinkage are 30.21 wt% and 3.17%, respectively. Furthermore, the porosity decreases from 62.3% to 45.28%, whereas the flexural strength increases from 1.91 to 7.52 MPa. This study provides a process reference for the efficient preparation of SiO₂ ceramics for complex hollow turbine blade cores.