Mechanical properties and fracture mechanism of 3D-printed honeycomb mullite ceramics fabricated by stereolithography

Honeycomb mullite ceramics with controllable pore geometries were prepared using stereolithography 3D printing. The influence of sintering temperature on the phase evolution, microstructure and compressive strength of honeycomb mullite ceramics was explored. The results showed that the mullite phases were basically completely transformed for the sample sintered at 1600 degrees C. As the sintering temperature increased, a huge number of rod-like mullite grains were generated through the dissolution-precipitation mechanism. As a result, the apparent porosity was reduced, while the densification and compressive strength were improved. Furthermore, the impact of the pore geometry on the mechanical properties of the sample was also investigated. Among all the honeycomb mullite ceramics, the compressive strength of the sample with square pores reached a maximum value of approximately 206.71 MPa. In addition, the compressive strength of honeycomb mullite was simulated using SolidWorks software. The results were in good agreement with the experimental data. The fracture behavior of honeycomb mullite ceramics exhibited three stages, including the linear elastic, plateau, and densification regions and the fracture mechanism was mainly layer-by-layer fracture of the pore structure.