Design and mechanical/thermal properties of in-situ synthesized mullite in SLA 3D printing Al 2 O 3 -SiO 2 ceramic

Porous mullite ceramics with complex geometry were developed by stereolithography (SLA) combined with an in-situ reaction sintering method. The effects of the sintering temperature and holding time on the phase evolution, microstructure, and mechanical and thermal properties of the samples were thoroughly investigated. The findings suggested that the sintering temperature played a favorable role in promoting the mullitization reaction, whereas the holding time exerted a limited effect on this reaction. As the temperature increased, both the mullite content and the pore size increased, the bulk density and the thermal properties decreased and the flexural strength showed a “Z” pattern. Furthermore, the thermal conductivity coefficient and thermal diffusion coefficient decreased. In comparison, extending the holding time did not cause noticeable changes in the bulk density and apparent porosity, but led to notable changes in the flexural strength. As a result, when the samples were sintered at 1600 °C for 6 h, they achieved the lowest apparent porosity of 41.4 % and the highest flexural strength of 62.47 MPa. Additionally, the thermal conductivity coefficient and thermal diffusion coefficient were 1.61 W/(m·K) and 0.91 mm 2 /s, respectively. The successful development of porous mullite ceramics with intricate geometries through SLA 3D printing presents promising prospects for their utilization in various applications, including thermal insulation, high-temperature adsorption, and catalysis.