UV‐Curing Assisted Direct Ink Writing of Dense, Crack‐Free, and High‐Performance Zirconia‐Based Composites With Aligned Alumina Platelets

Abstract Additive manufacturing (AM) of high‐performance structural ceramic components with comparative strength and toughness as conventionally manufactured ceramics remains challenging. Here, a UV‐curing approach is integrated in direct ink writing (DIW), taking advantage from DIW to enable an easy use of high solid‐loading pastes and multi‐layered materials with compositional changes; while, avoiding drying problems. UV‐curable opaque zirconia‐based slurries with a solid loading of 51 vol% are developed to fabricate dense and crack‐free alumina‐toughened zirconia (ATZ) containing 3 wt% alumina platelets. Importantly, a non‐reactive diluent is added to relieve polymerization‐induced internal stresses, avoid subsequent warping and cracking, and facilitate the de‐binding. For the first time, UV‐curing assisted DIW‐printed ceramic after sintering reveals even better mechanical properties than that processed by a conventional pressing. This is attributed to the aligned alumina platelets, enhancing crack deflection and improving the fracture toughness from 6.8 ± 0.3 MPa m^0.5 (compacted) to 7.4 ± 0.3 MPa m^0.5 (DIW). The four‐point bending strength of the DIW ATZ (1009 ± 93 MPa) is also higher than that of the conventionally manufactured equivalent (861 ± 68 MPa). Besides homogeneous ceramic, laminate structures are demonstrated. This work provides a valuable hybrid approach to additively manufacture tough and strong ceramic components.