Research Progress on the Formation and Suppression of Pore Defects in Ultra-high Temperature Oxide Ceramics by Laser Additive Manufacturing

Ultra-high temperature oxide ceramics, known for their outstanding high-temperature strength, microstructural stability, oxidation and corrosion resistance, are anticipated to serve as the next generation of ultra-high temperature structural materials, suitable for prolonged use in high-temperature oxidizing environments, and are expected to have broad application potential in the aerospace sector.In recent years, laser additive manufacturing (LAM) technology has emerged as a prominent method for the preparation of ultra-high temperature oxide ceramics, 9 , : 945 characterized by advantages such as rapid near-net shaping, mold-free production, and high flexibility for fabricating complex-shaped parts, thereby establishing itself as a significant research hotspot.However, ceramics are highly prone to pore defects during LAM process, which not only hinders the subsequent deposition of samples but also leads to deterioration in the surface quality and mechanical properties of formed parts.This review firstly provides an overview of the basic principles and process characteristics of three LAM techniques, including selective laser sintering (SLS), laser powder bed fusion (LPBF), and laser directed energy deposition (LDED).It focuses on characteristics of pore defects, flow characteristics of molten pool, and formation mechanism of pore defects in the LAM of ultra-high temperature oxide ceramics.Furthermore, their research progress in suppressing pore defects is detailed from three aspects: optimization of process parameters, outfield assistance, and second-phase doping.Finally, their challenges associated with achieving practical engineering applications are summarized, along with prospective development trends and breakthrough points in the field, focusing on suppression of forming defects, powder characteristics and subsequent heat treatment.