Investigation of curing behavior and mechanical properties of SiC ceramics prepared by vat photopolymerization combined with pressureless liquid-phase sintering using Al2O3-coated SiC powder

Preparation of SiC ceramics via vat photopolymerization can enhance the use of SiC ceramics in defense, aerospace, and other fields. However, the high ultraviolet absorbance and refractive index of SiC powder present challenges in achieving the desired curing depth for SiC slurry in vat photopolymerization. Additionally, the low sintering activity of SiC powder hinders the densification of 3D-printed SiC ceramics. Consequently, the fabrication of SiC ceramics using vat photopolymerization 3D printing technology encounters significant challenges. This study proposes a method of improving the curing properties of SiC slurry with Al2O3-coated SiC powder. The gap between SiC particles was optimized by incorporating small particle beta-SiC with enhanced sintering activity. The effects of Al2O3 coating modification and beta-SiC percentage in SiC powder system on the UV absorbance of SiC powder, rheology and curing properties of SiC slurries, and sintering properties of SiC ceramics were thoroughly investigated. Furthermore, the density, flexural strength, and elastic modulus of the sintered parts prepared by vat photopolymerization combined with the pressureless liquid-phase sintering process achieve 2.82 +/- 0.07 g/ cm3, 225.3 +/- 13.6 MPa, and 94.9 +/- 5.5 GPa, respectively. These properties are comparable to those of other currently available 3D-printed SiC ceramics but are easier to manipulate and achieve, showcasing its competitiveness.