Tunable Size of Hierarchically Porous Alumina Ceramics Based on DIW 3D Printing Supramolecular Gel

Three-Dimensional Printing of Cuttlebone-Inspired Porous Ceramic Materials

Lightweight and strong ceramic materials are attractive for tissue engineering, aerospace, armor systems, and many high-temperature applications. Cuttlebone, primarily composed of bioceramics, features a unique S-shaped wall structure that contributes significantly to its remarkable mechanical properties. Here, we explore the hierarchical structure and components of the cuttlebone and reveal the high ceramic content in S-shaped walls. Inspired by the design of the cuttlebone, we developed a high ceramic loading slurry for three-dimensional printing cuttlebone-like structures. As shown in the compression test, the fabricated bioinspired ceramics exhibit excellent mechanical properties and can withstand 1.07 million times their own weight, outperforming traditional ceramic foams. The specific strength and modulus are 59.5 and 785.6 MPa/(g cm-3), 9 and 36 times that of the natural cuttlebone. The failure mechanisms are also systematically studied on the basis of tuning the structural parameters. These findings provide effective solutions and inspiration in fabricating high-performance ceramic structural materials.

Optimization of 3D Printing Parameters for Alumina Ceramic Based on the Orthogonal Test

In this paper, an alumina ink with good rheological properties was successfully prepared using pseudoboehmite as the main component, nitric acid as the colloidal solvent, and sesbania powder as the lubricant. The impact of nine different ink formulations, namely, Ink1 to Ink9, on the printability and rheological features of the ink was investigated. Consequently, it was found that Ink3 with 5 wt % nitric acid and 5 wt % sesbania powder exhibited the most favorable formability. This ink was utilized to fabricate alumina samples with direct ink writing (DIW) three-dimensional (3D) printing technology. The printed alumina samples were characterized using an automatic Brunauer-Emmett-Teller, X-ray diffractometer, Fourier transform infrared spectroscopy, and scanning electron microscope. To obtain the optimal printing parameters, a three-factor and three-level orthogonal test was designed to research the influences of different 3D printing parameters (filling ratio, nozzle diameter, and layer thickness) on the specific surface area, pore characteristics (size and volume), and radial crushing strength of the alumina specimens. The primary and secondary orders of the effects on the radial crushing strength and pore structure were determined through analysis of the experimental data. The experimental results showed that the alumina sample with a filling ratio of 80%, nozzle diameter of 0.6 mm, and layer thickness of 0.3 mm was found to have better strength of 48.07 ± 9.53 N/mm and specific surface area of 185.7315 m2/g. This study provides a theoretical base for the preparation of alumina carriers by DIW 3D printing.

Catalytic Materials by 3D Printing: A Mini Review

Catalytic processes are the dominant driving force in the chemical industry, proper design and fabrication of three-dimensional (3D) catalysts monoliths helps to keep the active species from scattering in the reaction flow, improve high mass loading, expose abundant active catalytic sites and even realize turbulent gas flow, greatly improving the catalytic performance. Three-dimensional printing technology, also known as additive manufacturing, provides free design and accurate fabrication of complex 3D structures in an efficient and economic way. This disruptive technology brings light to optimizing and promoting the development of existing catalysts. In this mini review, we firstly introduce various printing techniques which are applicable for fabricating catalysts. Then, the recent developments in 3D printing catalysts are scrutinized. Finally, challenges and possible research directions in this field are proposed, with the expectation of providing guidance for the promotion of 3D printed catalysts.

Wet-spinning multi-component low-molecular-weight gelators to print synergistic soft materials

Two different low-molecular-weight gelators (LMWGs) have been 3D-printed as filaments by wet-spininng. When the two LMWGs are simultaneously wet-spun, the co-assembled hybrid gel filaments combine the individual properties of the two gelators (dynamic pH response and in-situ metal nanoparticle formation) in synergistic ways, creating gel objects with new properties.

Hierarchical Porous Ceramics with Distinctive Microstructures by Emulsion-Based Direct Ink Writing

Hierarchical porous materials are ubiquitous in nature and have inspired the fabrication of cellular structures for a multitude of applications. As an extrusion-based 3D printing technique, direct ink writing (DIW) allows for customizable design and accurate control of printed structures. Recently, its combination with colloidal processing methods used for bulk porous ceramics, such as emulsion templating, has further extended its capability of fabricating porous ceramics across multiple length scales. In light of the recent development, the ink formulation for emulsion-based DIW can be further explored, and there is still a need for a better understanding of the structure-property relationship. Herein, we introduce two types of gelling additives, i.e., poly(ethylenimine) (PEI) and Pluronic F-127, respectively, into particle-stabilized emulsions and fabricate hierarchical porous alumina lattices by DIW. We discover that the two gelling additives can lead to distinctive microstructures due to their different gelling mechanisms. Moreover, the 3D printed hierarchical porous ceramic lattices are found to exhibit a potential energy absorption property. The effects of ink formulations, including gelling additives and solid loading, on ink rheology, microstructure, and mechanical properties are investigated. The 3D printed hierarchical porous ceramic lattices exhibit a high average porosity of 73.7%-79.3% with an average compressive strength of 1.53-9.61 MPa and a specific energy absorption of 0.33-2.67 J/g. Featuring two distinctive microstructures with tunable structural features and mechanical properties, the 3D printed hierarchical porous ceramics in this study have potential in many applications, including lightweight structures, tissue engineering scaffolds, filtration, etc.