Long-term stabilized amorphous calcium carbonate-an ink for bio-inspired 3D printing

Natural systems often form complex mineral structures from amorphous calcium carbonate (ACC) precursors. These structures remain stable long enough to shape before crystallizing. Prior research has shown ACC is common in biominerals like shells and skeletons. However, ACC typically transforms rapidly, limiting its use in synthetic systems. This gap motivated researchers to explore ACC stabilization for 3D printing applications. No prior work had resolved how to maintain ACC stability for extended periods. That uncertainty drove the development of ACC-based inks with long-term stability. This paper introduces a novel approach to ACC-based 3D printing inspired by natural systems.

The aim is to develop a 3D printing method using ACC stabilized with magnesium. This approach mimics natural biomineralization to enable complex ceramic shapes. The study focuses on ACC's stability and post-printing crystallization behavior. Researchers sought to extend ACC's amorphous state beyond typical transformation times. They also wanted to control crystallization after printing at low temperatures. The motivation stems from the need for low-temperature ceramic fabrication techniques. This work addresses the challenge of ACC's rapid transformation in artificial systems. The goal is to enable bio-inspired 3D printing of ceramics with controlled crystallization.

The study used robocasting, a 3D printing method, to fabricate ACC-based objects. ACC pastes were formulated with magnesium to enhance long-term stability. Different organic binders were tested for their impact on ACC properties. Printed objects were analyzed for ACC stability over extended periods. Crystallization was induced after printing to assess morphology and Mg content. Temperature effects on crystallization were evaluated in controlled environments. The role of binders in ACC stabilization was examined through comparative analysis. This approach allowed researchers to isolate ACC's behavior under various conditions.

ACC remained amorphous for over two months after printing, a first in synthetic systems. Crystallization occurred only after printing and at lower temperatures than traditional methods. Mg content in ACC was influenced by the choice of organic binder used in the paste. The ACC-based ink achieved high solids loading, enabling dense 3D structures. Post-printing crystallization was controlled, allowing for tailored material properties. This method enabled the fabrication of complex shapes without high-temperature sintering. The ACC's stability and controlled crystallization suggest potential for ceramic printing. These findings demonstrate a new route for bio-inspired ceramic fabrication.

The ACC remained stable for extended periods, as stated by the authors. Crystallization could be delayed until after printing, as observed in the study. The use of Mg and organic binders influenced ACC behavior, as shown in the results. This method may offer a new pathway for low-temperature ceramic printing. The authors propose that this approach could be applied to various ceramic materials. The study suggests ACC-based inks could be used for bio-inspired 3D printing. The findings align with the natural biomineralization process studied in the abstract. The researchers suggest this method could enable new applications in ceramic fabrication.