Magnetically-Assisted Slip Casting of Bioinspired Heterogeneous Composites (1605.07461v1)

Abstract: Composites are often made heterogeneous in nature to fulfill the functional demands imposed by the environment, but remain difficult to fabricate synthetically due to the lack of adequate and easily accessible processing tools. We report on an additive manufacturing platform to fabricate complex-shaped parts exhibiting bio-inspired heterogeneous microstructures with locally tunable texture, composition and properties and unprecedentedly high volume fractions of inorganic phase (up to 100%). The technology combines an aqueous-based slip casting process with magnetically-directed particle assembly to create programmed microstructural designs using anisotropic stiff platelets in a ceramic, metal or polymer functional matrix. Using quantitative tools to control the casting kinetics and the temporal pattern of the applied magnetic fields, we demonstrate that this robust approach can be exploited to design and fabricate heterogeneous composites with thus far inaccessible microstructures. Proof-of-concept examples include bulk composites with periodic patterns of micro-reinforcement orientation and tooth-like bilayer parts with intricate shapes displaying site-specific composition and texture.

• The paper introduces a magnetically-assisted slip casting method that enables precise control over composite microstructures with up to 60 vol% inorganic phase.
• Researchers achieve biomimetic reinforcement orientations, increasing fracture toughness by a factor of 3 to 5 compared to conventional composites.
• The study paves the way for scalable production of advanced materials applicable to aerospace, biomedical, and smart technology industries.

Magnetically-Assisted Slip Casting for Bioinspired Heterogeneous Composites

The paper "Magnetically-Assisted Slip Casting of Bioinspired Heterogeneous Composites" by Le Ferrand, Bouville, Niebel, and Studart presents a sophisticated additive manufacturing approach to synthesize bioinspired heterogeneous composites with precise control over microstructures and compositions. This research marks a significant advancement in the domain of materials science, specifically aiming to mimic the intricate architectures observed in natural composites.

Overview of the Methodology

The authors introduce a novel Magnetically-Assisted Slip Casting (MASC) process. This methodology integrates an aqueous-based slip casting with magnetically-directed particle assembly, enabling the creation of complex-shaped parts with bio-inspired heterogeneous microstructures. The approach utilizes anisotropic stiff platelets dispersed in various matrices, such as ceramic, metal, or polymer, and it allows for local texture and composition tuning. The utilization of superparamagnetic iron oxide nanoparticles (SPIONs) is essential to impart magnetic responsiveness to the anisotropic particles, which are then oriented using a programmable magnetic field during the slip casting process. The innovative use of MASC technology provides a route to achieve unprecedentedly high volume fractions of the inorganic phase, mimicking natural composite structures.

Main Findings

The paper offers proof-of-concept examples demonstrating the capability of MASC to fabricate bulk composites with periodic micro-reinforcement orientations and tooth-like bilayer parts with site-specific textures. The paper meticulously details the process of controlling the orientation of anisotropic particles through the synchronization of the casting process with the tailored application of magnetic fields. In particular, the authors report achieving a high alumina platelet volume fraction of up to 35% in the initial casting, which is later increased to 60 vol% through pressing. This enables the creation of multiscale, textured composites that exhibit enhanced mechanical properties, exhibiting an increase in fracture toughness when compared to traditional synthetic composites.

Numerical Results and Implications

The results illustrate strong alignment and structural fidelity capable of replicating natural composites, such as dental structures and nacre-inspired materials. For instance, the research demonstrates enhanced crack growth resistance curves, reflecting a toughening mechanism that parallels the remarkable properties found in biological materials. These composites show fracture toughness increases by a factor of 3 to 5 relative to conventional equivalents. This substantial improvement in mechanical performance indicates the MASC process's potential in developing materials for applications requiring unique combinations of strength, durability, and functionality.

Future Research Directions and Applications

The implications of this research extend into both practical and theoretical realms. Practically, the MASC process could revolutionize the development of materials in industries demanding highly customized material properties, such as aerospace, biomedical implants, and electronics. The theoretical advancements in understanding material alignment and consolidation mechanisms could further influence biomimetic material design, providing insights into natural composite structures.

The paper underscores the potential for future research to further refine and expand the utility of MASC. The inclusion of multifunctional composites, such as those with integrated electrical and thermal properties, could open new avenues in smart materials and responsive systems. Additionally, exploring the scalability of the MASC process could bridge the gap between laboratory research and industrial application.

Conclusion

In summary, this paper represents a noteworthy advancement in fabricating bioinspired heterogeneous composites through the MASC framework. By effectively emulating natural composite architectures, the research outlines a robust process for achieving structural diversity and functional performance previously inaccessible in synthetic composites. The insights and methodologies presented could serve as a keystone for future developments in advanced material design and biomimicry.