Bimodal powder optimization in SiC binder jetting for mechanical performance

•Introduced bimodal SiC powder, enhancing BJ process and powder properties.•All stages of microstructure and performance are investigated.•The flexural strength and fracture toughness increased by 42.3 % and 25.3 %. Binder jetting (BJ) additive manufacturing has emerged as a promising technique for batch production of complex silicon carbide (SiC) ceramic components. However, the utilization of coarse powder in BJ often leads to lower density and strength in green parts and final composites compared to conventional fabrication methods. This study aims to enhance the mechanical performance of SiC ceramics through a novel bimodal SiC powder formulation for BJ, complemented by phenolic resin impregnation and pyrolysis (PRIP) and liquid silicon infiltration (LSI). The optimal ratio of bimodal powder, comprising 75 % coarse and 25 % fine powder, was determined through a comprehensive analysis of the microstructure and properties at various stages of the preparation process. The bimodal powder achieves a packing density of 48.3 % and exhibits satisfactory flowability. Notably, the density of the green part reaches 1.78 g/cm3, which is 31 % and 4.7 % higher than that of unimodal fine and coarse powders, respectively. Following the LSI process, the final Si-SiC composites display a high flexural strength of 276.6 ± 13.3 MPa and fracture toughness of 3.52 ± 0.12 MPa·m1/2. These values represent increases of 42.4 % and 25.3 %, respectively, compared to the composites derived from unimodal coarse powder. The material compositions and fabrication strategies proposed in this work offer an effective pathway for creating high-performance SiC ceramic composites via binder jetting. [Display omitted]