Core–shell powder strategy for additive manufacturing of ceramics: application to direct powder bed selective laser processing of silicon carbide

The production of innovative ceramic powders through surface functionalization of grains, featuring a core–shell structure, accelerates mass diffusion and enhances sintering behavior. This approach significantly impacts the additive manufacturing field. In this study, a commercial SiC preceramic compound from the polycarbosilane family, specifically poly(silaethylene), was grafted onto the surface of Silicon Carbide (SiC) particles, forming a conformal molecular layer. Powder Bed Selective Laser Processing, also known as Selective Laser Sintering/Melting, was employed to fabricate 3D SiC and surface-modified SiC parts, enabling a comparative analysis of the efficiency and impact of surface modification in the manufacturing process. The surface functionalization increases densification by at least 5% without affecting the final phases of the manufactured parts. Additionally, Spark Plasma Sintering (SPS) was employe as a post-treatment to further densify the samples, increasing their final density and eliminating residual silicon and carbon, which are produced due to the undesired decomposition of SiC during the manufacturing process.