Ceramic matrix composite additive manufacturing: Defect formation, inheritance, and inhibition

Ceramic matrix composites (CMCs) are critical material for high-performance applications in aerospace, automotive, and biomedical engineering because of their exceptional thermal stability, mechanical strength, and biocompatibility. Additive manufacturing (AM) offers a promising approach for the development of CMCs, yet its multi-step processes can introduce matrix defects that impede mechanical property enhancement and limit engineering applications. This article systematically compares process-preform structure coupling in four major additive manufacturing techniques and three categories of ceramic matrices. It clarifies the mechanisms of defect formation, inheritance, and inhibition from the printing stage through densification. For oxide ceramic-based CMCs, such as zirconia-toughened alumina (ZTA), optimization of feedstock composition, printing parameters, and sintering conditions reduces porosity and refines microstructures. In non-oxide ceramic-based CMCs, such as SiC-CMCs, strategies including tailored powder grading, fiber coatings, and densification via chemical vapor infiltration (CVI), precursor infiltration and pyrolysis (PIP), or reactive melt infiltration (RMI) mitigate defects and enhance toughness. For precursor-derived ceramic (PDC)-based CMCs, such as SiOC-CMCs, precise control of reinforcement parameters, precursor content, and pyrolysis conditions minimizes shrinkage-related defects. Integrative strategies across these systems substantially improve the mechanical properties of CMCs by enabling more effective control of defect evolution. These findings offer new perspectives for advancing the engineering applications of high-performance produced through additive manufacturing.