Microstructure and fracture behavior of single-layer SiC/Al2O3 composite prepared by selective laser sintering combined with nano gel impregnation and sintering

A single-layer 3D printed SiC/Al 2 O 3 composite with a thickness of 100 μm was fabricated using selective laser sintering (SLS) combined with alumina (Al 2 O 3 ) nano sol impregnation and sintering. The microstructure and mechanical properties of the composites were systematically studied. With increasing cycles of nano-sol impregnation, porosity significantly decreased to 18.1% with a reduction of 61.9%, while the density increased to 2.9 g/cm 3 with an increase of 70.5%. The pore exhibited a graded characteristic from the surface to the interior. Phase analysis confirmed that the composites primarily were composed of SiC and Al 2 O 3 , and a minor amount of SiO 2 . The fracture behavior of the composites was investigated in detail from micro to macro scales using in-situ micropillar compression, nanoindentation, and three-point bending tests. The composite exhibits predominantly brittle fracture characteristics, attributed to a combination of an interfacial defect, inherent pore-induced stress concentration and the low shear strength of amorphous SiO 2 and carbon-rich layers, which induce localized inelastic deformation and shear dominated brittle fracture. Fractographic analysis confirmed that cracks preferentially nucleated and propagated along the SiC/Al 2 O 3 interface, producing river-like fracture patterns and leading to interface-dominated brittle failure. These findings provide critical insights for optimizing the interfacial design strategies to enhance the mechanical performance of SiC/Al 2 O 3 composites.