In-situ quantitative characterization of uniformity evolution in additively manufactured SiC composites

Abstract

Over the past few years, silicon carbide (SiC) composites have gained significant industrial attention owing to their exceptional mechanical properties, chemical inertness, and favorable strength-to-weight ratio. Selective laser sintering (SLS) has emerged as an efficient approach for manufacturing SiC composites, offering unprecedented geometric flexibility. However, the layer-wise manufacturing process involved in this approach often results in microstructural non-uniformity across interlayers. In this study, we propose a non-destructive methodology that integrates phase-contrast micro-computed tomography with grayscale entropy index (GEI) analysis to quantitatively evaluate microstructural uniformity in SLS-fabricated SiC composites. The results indicated that the SLS process introduces significant periodic fluctuations in the microstructural uniformity of the composites during the green body and debinded body stages. These fluctuations exhibit a spatial period closely matching the powder layer thickness, with the GEI values effectively capturing both the uniformity and variability of the composite microstructure. Following silicon infiltration, the sintered ceramic stage shows a marked reduction in these fluctuations, resulting in a highly cohesive and uniform microstructure that improves the overall structural integrity of the additively manufactured SiC composites. The insights gained from this study will facilitate systematic optimization of process parameters in the additive manufacturing of SiC composites for industrial applications.