Additive manufacturing of high-temperature ceramics for extreme environments: progress, challenges, and future perspectives

Additive manufacturing (AM) emerges as a disruptive route for fabricating high-temperature ceramics and ultra-high-temperature ceramics (UHTCs) for extreme environments, enabling complex architecture and property control not feasible with conventional forming and sintering. This review critically synthesizes the state-of-the-art in key ceramic AM techniques—including selective laser reaction pyrolysis (SLRP), direct ink writing (DIW), stereolithography (SLA), binder jetting, and electron beam powder bed fusion (EB-PBF)—with an emphasis on their process windows, microstructural control, and extreme environment performance. The major issues and bottlenecks for AM UHTCs, such as porosity, anisotropy, defect control, and scalability, are addressed, including their implications for aerospace, energy, and nuclear applications. The discussion in the conclusion section is about the future developments on aspects of process optimization (AI-enhanced control), multifunctional material design, in-situ monitoring, and development of multi-physics testing and certification processes to aid in the transfer of AM UHTCs from the lab to application.