Fabrication and thermal shock resistance of porous silicon carbide ceramics prepared via DLP 3D printing using PMMA microspheres as pore-forming agents

Polymethyl methacrylate (PMMA) microspheres were used as pore-forming agents in the fabrication of porous silicon carbide (SiC) ceramics to control the pore structure and improve their high-temperature performance. PMMA microspheres reduced the viscosity and the overall attenuation coefficient of the SiC slurry, thereby improving its rheological stability and curing depth. As PMMA content increased from 0 to 60 vol%, open porosity rose from 26.27% to 54.98%, while bulk density decreased from 2.21 g/cm 3 to 1.53 g/cm 3 . PMMA decomposition generated uniform micrometer-scale spherical pores in the ceramic matrix. An appropriate open porosity enhanced thermal shock resistance by blunting crack tips and buffering thermal stress, while excessive open porosity caused stress concentration and accelerated crack propagation. The porous SiC ceramics containing 20 vol% PMMA microspheres exhibited the highest thermal shock resistance, with a critical temperature difference ( Δ T c $\Delta T_c$ ) of 338.3 °C.