Digital light processing 3D printing of large-scale and crack-free ceramics with perforated internal honeycomb structures

Digital light processing (DLP) enables high-resolution and efficient ceramic additive manufacturing, yet the fabrication of large-scale, crack-free ceramic parts remains severely constrained by critical defects arising during debinding and sintering. To address this challenge, we propose an approach leveraging honeycomb sandwich structures with perforated sidewalls to mitigate crack formation. Key structural parameters, including the outer wall thickness (a) and honeycomb cell characteristics such as sidewall height (h), length (l), thickness (t), and perforation diameter (d), are systematically investigated to evaluate their effects on manufacturability and mechanical performance. The characterisations of sintered ceramic parts further elucidate the mechanism of crack formation and validate the approach in this work. Through a comprehensive consideration of fabrication limits, slurry discharge efficiency and mechanical behaviour, the honeycomb sandwich structure with optimised structural parameters exhibits superior mechanical properties after sintering, achieving more than twice the specific modulus and specific strength of the solid references with the same overall dimensions in three-point bending tests. This work provides valuable guidelines for the structural design and fabrication of honeycomb sandwich ceramic structures to achieve large-scale crack-free ceramic parts, demonstrating great promise for lightweight applications.