Curing behavior and mechanical properties of polycarbosilane-derived silicon carbide ceramics by digital light processing

Stereolithography-based additive manufacturing provides feasible path for the preparation of high-purity SiC ceramics with complex configurations; however, the challenges in curing ability of the photosensitive slurry and the densification of printed body inhibit mechanical properties of the sintered ceramics. Here, a polymer-derived ceramic path was proposed for preparing high-purity SiC ceramics by digital light processing with polycarbosilane (PCS) as the SiC precursor. By constructing PCS@SiC core-shell structure in the starting ceramic powders, the curing ability of the photosensitive slurry was enhanced with the increase of PCS content. When sintered at 1100 °C, PCS pyrolyzed to generate amorphous SiC and β-SiC with fine grain sizes; then the yielded SiC grew to form SiC whisker, SiC nanofiber and SiC columnar grain with the increase of PCS content. As a result, the flexural strength increased from 46.1 MPa to 56.2 MPa for the specimen sintered at 1900 °C due to the strengthening and toughening effect provided by the above one-dimensional materials.