UV-curing Assisted Direct Ink Writing of Dense, Crack-Free And High-Performance Zirconia-Based Composites with Aligned Alumina Platelets.

Additive manufacturing (AM) of high-performance structural ceramic components with comparative strength and toughness as conventionally manufactured ceramics remains challenging. Here, an 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% were developed to fabricate dense and crack-free alumina-toughened zirconia (ATZ) containing 3 wt% alumina platelets. Importantly, a non-reactive diluent was 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 revealed even better mechanical properties than that processed by a conventional pressing. This was 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 4-point bending strength of the DIW ATZ (1009 ± 93 MPa) was also higher than that of the conventionally manufactured equivalent (861 ± 68 MPa). Beside homogeneous ceramic, laminate structures were demonstrated. This work has provided a valuable hybrid approach to additively manufacture tough and strong ceramic components. This article is protected by copyright. All rights reserved.