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Abstract
Alumina toughened zirconia (ATZ) ceramics combine high biocompatibility with remarkable mechanical properties, making them suitable for dental and orthopedic implant applications. Producing these ATZ ceramics using slurry-based additive manufacturing necessitates homogeneous, stable suspensions with controlled particle sizes. Stabilizing such systems with the appropriate type and amount of dispersant is challenging, particularly since multi-component systems are prone to hetero-coagulation. In this study, ATZ powders with different surface areas were investigated to determine the optimum concentration of three commercially available dispersants: Darvan CN, Darvan 821 A, and Dolapix CE64, which have been successfully used to stabilize Al2O3 and 3Y-TZP suspensions. Based on zeta potential (0.01 vol% suspensions), agglomerate size (0.01 vol% suspensions), sedimentation (10 vol% slurries), and rheological (40 vol% slurries) characterization, the optimum dispersant concentrations were found to be 0.50 mg/m2 for Dolapix CE64, 0.75 mg/m2 for Darvan 821 A, and 1.50 mg/m2 for Darvan CN. Among the studied dispersants, Dolapix CE64 was the most effective in terms of reduced sedimentation, smaller agglomerate size (0.70 μm), flow behavior, and low resistance to structure breakdown. The rheological assessment showed that slurries prepared with ATZ powder featuring a smaller specific surface area (7.3 m2/g) resulted in lower viscosity, critical stress, and equilibrium storage and loss moduli compared to those prepared with higher specific surface area (13.3 m2/g) starting powder. The sedimentation analysis however revealed that the larger specific surface area ATZ powder exhibited higher slurry stability. While 38 vol% ATZ pastes without dispersant showed inhomogeneous extrusion and the presence of aggregates, the filaments extruded from 45 vol% paste with 0.50 mg/m2 Dolapix CE64 had a homogeneous and smooth structure and were free of aggregates, highlighting the importance of the dispersant addition for DIW.

Abstract
Abstract 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 m0.5 (compacted) to 7.4 ± 0.3 MPa m0.5 (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

Abstract
A bottleneck limiting the practical application of lithium metal anodes is the uncontrolled growth of lithium dendrites caused by gradient distributed Li+ from separators to collectors. Herein{,} 3D-printed frameworks with a gradient distributed heterojunction and fast Li+ conductivity interfaces are developed to regulate the Li+ distribution and the direction of dendrite growth. More importantly{,} the effect of different Li+ concentration gradient frameworks on Li+ deposition behavior was analyzed in detail. Synchrotron X-ray tomography demonstrates that macropores dominate the framework{,} which effectively suppresses the volume change caused by lithium deposition. DFT calculations confirm the high lithiophilicity of γ-Al2O3 and the graphene heterojunction. Synchrotron radiation-based soft X-ray absorption spectroscopy illustrates the fast Li+ conductivity Li–Al–O interface resulting from the shortened Al–O bond distance. Benefiting from the higher Li+ concentration differences during the dissolution process and Li–Al–O interfaces{,} the gradient framework can achieve a high rate performance of ∼40 mV overpotential at 10 mA cm−2 and long cycle stability of ∼1500 h at 1 mA cm−2.

Abstract
Sensors are crucial in the understanding of machines working under high temperatures and high-pressure conditions. Current devices utilize polymeric materials as electrical insulators which pose a challenge in the device’s lifespan. Ceramics, on the other hand, is robust and able to withstand high temperature and pressure. For such applications, a co-fired ceramic device which can provide both electrical conductivity and insulation is beneficial and acts as a superior candidate for sensor devices. In this paper, we propose a novel fabrication technique of complex multi-ceramics structures via 3D printing. This fabrication methodology increases both the geometrical complexity and the device’s shape precision. Structural ceramics (alumina) was employed as the electrical insulator whilst providing mechanical rigidity while a functional ceramic (alumina-doped zinc oxide) was employed as the electrically conductive material. The addition of sintering additives, tailoring the printing pastes’ solid loadings and heat treatment profile resolves multi-materials printing challenges such as shrinkage disparity and densification matching. Through high-temperature co-firing of ceramics (HTCC) technology, dense high quality functional multi-ceramics structures are achieved. The proposed fabrication methodology paves the way for multi-ceramics sensors to be utilized in high temperature and pressure systems in the near future.

Abstract
Bulk hierarchical porous ceramics with unprecedented strength-to-weight ratio and tunable pore sizes across three different length scales are printed by direct ink writing. Such an extrusion-based process relies on the formulation of inks in the form of particle-stabilized emulsions and foams that are sufficiently stable to resist coalescence during printing.