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1. Additive Manufacturing of Porous Ceramics With Foaming Agent

   https://doi.org/10.1115/1.4051828  

   Guo, Zipeng; An, Lu; Lakshmanan, Sushil; Armstrong, Jason N.; Ren, Shenqiang; Zhou, Chi (February 2022, Journal of Manufacturing Science and Engineering)

   Abstract The macro-porous ceramics has promising durability and thermal insulation performance. As porous ceramics find more and more applications across many industries, a cost-effective and scalable additive manufacturing technique for fabricating macro-porous ceramics is highly desirable. Herein, we reported a facile additive manufacturing approach to fabricate porous ceramics and control the printed porosity. Several printable ceramic inks were prepared, and the foaming agent was added to generate gaseous bubbles in the ink, followed by the direct ink writing and the ambient-pressure and room-temperature drying to create the three-dimensional geometries. A set of experimental studies were performed to optimize the printing quality. The results revealed the optimal process parameters for printing the foamed ceramic ink with a high spatial resolution and fine surface quality. Varying the concentration of the foaming agent enables the controllability of the structural porosity. The maximum porosity can reach 85%, with a crack-free internal porous structure. The tensile tests showed that the printed macro-porous ceramics possessed enhanced durability with the addition of fiber. With a high-fidelity three-dimensional (3D) printing process and the precise controllability of the porosity, we showed that the printed samples exhibited a remarkably low thermal conductivity and durable mechanical strength. 

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2. Digital Light Processing 3D‐Printed Porous Yttria‐Stabilized Zirconia with High‐Thermal Shock Resistance

   https://doi.org/10.1002/adem.202400206  

   Khakzad, Moein; Mosadegh, Mahdi; Sepasi, Zahra; Mehrdad, Ehsan; Alsup, Zachary; Minary‐Jolandan, Majid (September 2024, Advanced Engineering Materials)

   Advances in vat photopolymerization 3D printing have the potential to significantly improve the production of ceramic materials for electrochemical energy devices. Solid oxide fuel cells (SOFCs) and solid oxide electrolysis cells (SOECs) necessitate high‐resolution ceramic manufacturing methods, as well as precisely controlled porosity (≈20–40%) for optimal gas transport. Achieving a balance between this porosity and mechanical integrity, especially under thermal stress, remains a challenge. Herein, the successful fabrication of porous yttria‐stabilized zirconia (YSZ) ceramics using vat photopolymerization 3D printing is demonstrated, achieving porosities ranging from 6% to 40% and corresponding grain sizes of ≈80–550 nm. It is found that 3D‐printed YSZ with ≈33% porosity exhibited a Weibull modulus ofm = 5.3 and a characteristic strength of over 36 MPa. In the investigation, it is further revealed that these ceramics can withstand thermal shock up to 500 °C, retaining over 70% of their flexural strength. This remarkable performance suggests significant potential for 3D‐printed porous YSZ in SOFCs and SOECs, paving the way for potential improved efficiency, reduced fabrication costs, and innovative designs in these next‐generation clean energy technologies. 

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3. Development of bioinks for 3D printing microporous, sintered calcium phosphate scaffolds

   https://doi.org/10.1007/s10856-021-06569-9  

   Montelongo, Sergio A.; Chiou, Gennifer; Ong, Joo L.; Bizios, Rena; Guda, Teja (August 2021, Journal of Materials Science: Materials in Medicine)

   Abstract Beta-tricalcium phosphate (β-TCP)-based bioinks were developed to support direct-ink 3D printing-based manufacturing of macroporous scaffolds. Binding of the gelatin:β-TCP ink compositions was optimized by adding carboxymethylcellulose (CMC) to maximize the β-TCP content while maintaining printability. Post-sintering, the gelatin:β-TCP:CMC inks resulted in uniform grain size, uniform shrinkage of the printed structure, and included microporosity within the ceramic. The mechanical properties of the inks improved with increasing β-TCP content. The gelatin:β-TCP:CMC ink (25:75 gelatin:β-TCP and 3% CMC) optimized for mechanical strength was used to 3D print several architectures of macroporous scaffolds by varying the print nozzle tip diameter and pore spacing during the 3D printing process (compressive strength of 13.1 ± 2.51 MPa and elastic modulus of 696 ± 108 MPa was achieved). The sintered, macroporous β-TCP scaffolds demonstrated both high porosity and pore size but retained mechanical strength and stiffness compared to macroporous, calcium phosphate ceramic scaffolds manufactured using alternative methods. The high interconnected porosity (45–60%) and fluid conductance (between 1.04 ×10 −9 and 2.27 × 10 −9  m 4 s/kg) of the β-TCP scaffolds tested, and the ability to finely tune the architecture using 3D printing, resulted in the development of novel bioink formulations and made available a versatile manufacturing process with broad applicability in producing substrates suitable for biomedical applications. 

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4. 3D Printed CO ₂ ‐Based Triblock Copolymers and Post‐Printing Modification

   https://doi.org/10.1002/anie.202208355  

   Wei, Peiran; Bhat, Gulzar A.; Cipriani, Ciera E.; Mohammad, Hamza; Schoonover, Krista; Pentzer, Emily B.; Darensbourg, Donald J. (August 2022, Angewandte Chemie International Edition)

   Abstract We report the facile synthesis and 3D printing of a series of triblock copolymers consisting of soft and hard blocks and demonstrate that alkene pendant groups of the hard block can be covalently modified. The polymers are prepared using a salenCo(III)TFA/PPNTFA binary catalyst system and 1,2‐propanediol as a chain transfer agent, providing an efficient one‐pot, two‐step strategy to tailor polymer thermal and mechanical properties. Thixotropic inks suitable for direct ink write printing were formulated by dissolving the block copolymers in organic solvent and dispersing NaCl particles. After printing, porous structures were produced by removing solvent and NaCl with water to give printed structures with surfaces that could be modified via UV‐initiated thiol‐ene click reactions. Alternatively, a tetra‐thiol could be incorporated into the ink and used for cross‐linking to give objects with high solvent resistance and selective degradability. 

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5. Additive manufacturing of high‐density silicon carbide ceramics through post‐processing spark plasma sintering

   https://doi.org/10.1111/ijac.15167  

   Xiang, Yuhui; Doran, Spencer; Chang, Tzu‐Yi; Wang, Zexiao; Sangkagoon, Smitanan; Yeung, Yun; Xue, Fei; Cheng, Tian‐Le; Zhao, Dong; Lian, Jie; et al (May 2025, International Journal of Applied Ceramic Technology)

   Abstract This research advances the field of additive manufacturing (AM) of silicon carbide (SiC) ceramics by integrating spark plasma sintering (SPS) to enhance material density, mechanical strength, and thermal properties. Traditional AM techniques struggle to achieve the high‐density SiC required for demanding applications, such as aerospace engineering, where high thermal conductivity and mechanical strength are paramount. Our study addresses these challenges by incorporating SPS as a post‐processing step, achieving near‐theoretical maximum densities and significantly reducing porosity, thereby resulting in outstanding thermal conductivity in SiC ceramics. We developed a specialized SiC ink optimized for 3D printing, ensuring structural integrity after deposition through tailored rheological properties. The application of SPS facilitates rapid, uniform sintering, essential for attaining superior density, mechanical properties, and thermal performance. Our experimental results, confirmed through scanning electron microscopy analysis, demonstrate significant microstructural properties, mechanical strength, and thermal conductivity, showcasing the effectiveness of integrating SPS in AM processes. This innovative approach not only expands the capabilities of AM in producing complex, high‐density ceramic structures but also broadens the potential applications of SiC in demanding environments. 

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