Application of SiO2-coated SiC powder in stereolithography and sintering densification of SiC ceramic composites

Abstract

Stereolithography additive manufacturing of SiC ceramic composites has received much attention. However, the forming efficiency and mechanical properties of their products need to be improved. This study aimed to prepare SiC ceramic composites with complex shapes and high flexural strength using a combination of digital light processing (DLP) and reactive solution infiltration process (RMI). A low-absorbance SiO2 cladding layer was formed on the surface of SiC powder through a non-homogeneous precipitation process. With the densification of the cladding layer at high temperatures, SiO2-coated SiC composite powder was used to formulate a photosensitive ceramic slurry with a solid content of 44 vol%. The resulting slurry exhibited a considerable improvement in curing thickness and rate and was used to mold ceramic green body with a single-layer slicing thickness of 100 μm using DLP. The ceramic blanks were then sintered and densified using a carbon thermal reduction combined with liquid silica infiltration (LSI) process, resulting in SiC ceramic composites with a density of 2.87 g/cm3 and an average flexural strength of 267.52 ± 2.5 MPa. Therefore, the proposed approach can reduce the manufacturing cycle and cost of SiC ceramic composites.