Anisotropy in ceramic vat photopolymerization: Formation mechanisms, influence on properties, and manipulating strategies

Abstract

Ceramic vat photopolymerization (VPP) has recently emerged as a transformative technology, providing efficient, reliable, and highly customizable methods for fabricating ceramic components with excellent surface quality, precisely controllable structures, and programmable functionality. Despite its widespread adoption, the inherent issue of anisotropic properties, characterized by orientation-dependent features in VPP-manufactured ceramics, remains a significant barrier to broader applications in academic and engineering domains. Due to the complex photocuring behavior of ceramic suspensions and critical post-processing steps such as debinding and sintering, anisotropy in VPP-manufactured ceramics is more intricate compared to other materials. Numerous researches have shown that controlling on the inherent layered microstructure and orientation-dependent property is key for producing high-performance ceramic parts and promoting its industrialization. This review offers a comprehensive analysis of recent advancements in understanding anisotropic behavior in additive-manufactured ceramic components created using VPP. The discussion begins with an exploration of anisotropy formation mechanisms, emphasizing the evolution of the layered microstructure from the photocured ceramic monolayer to fully sintered ceramic parts. It then highlights the latest developments regarding the influence of anisotropy on various properties of VPP-printed ceramics, clarifying the interrelation between material, process, structure, and anisotropic properties. Additionally, strategies for mitigating or exploiting the undesirable anisotropy are critically examined, with a specific focus on the mechanisms underlying each approach. Finally, the review addresses existing challenges and potential directions for future research on anisotropy in VPP-manufactured ceramics.