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ADVANCED COMPOSITES INSPIRED BY NATURE

Final Report Summary - ACIN (ADVANCED COMPOSITES INSPIRED BY NATURE)

One of today’s crucial scientific challenges for the advance of strategic fields like transportation, building, energy or healthcare is the development of novel lightweight materials capable of providing exceptional performance under increasingly demanding environments, from high temperatures to corrosive media. Envisaged applications include high performance bearings, turbocharged rotors, fuel igniters, power generation turbines, components for armor or orthopedic implants. Materials currently available for these and many other applications are reaching their performance limits. In the search for inspiration, scientists and engineers have looked at the remarkable functional and mechanical properties of natural composites, like bone and nacre. These natural materials present unique combinations of strength and toughness and self-healing abilities achieved through the formation of complex hierarchical architectures and molecular scale interfacial engineering. However, we still do not have a clear idea of what role bio-inspiration should play in the development of new synthetic materials. We strongly believe that this important question must be addressed through the combination of new processing techniques able to achieve, in practical dimensions, design concepts found in natural materials, with a deep understanding of the relationships between structure and mechanical response, encompassing the influence of structural parameters acting at multiple length scales.
The overall objective of ACIN is to develop the science, methodologies and technologies necessary to fabricate novel nature-inspired composite materials based on innovative manufacturing techniques, e.g. freeze casting and spark plasma sintering. This involves the following main thrusts:
- Design of new experimental apparatus to manipulate the solidification of colloidal suspensions and control the architectures of the resulting scaffolds at multiple scales.
- To fabricate, in practical dimensions novel composite materials, based on the notion of hierarchical structures, “soft” and “hard” phases and engineered interfaces.
- To undertake a systematic structural and mechanical evaluation of the materials at multiple length scales.
The project has focused on: - studying the effect of freezing conditions and suspension composition for the control of architecture of freeze casted scaffolds (ceramic and nanocarbon-based materials); - development of several approaches have been developed to introduce different “soft-phases” in freeze casted porous structures in order to fabricate bio-inspired composites; - mechanical and structural characterization of the materials.

The main results of the project include:
- Development of methodologies based on cold finger patterning and external electrical fields for the alignment of ceramic lamellae over macroscopic dimensions during freezing.
- Development of high performance SiC porous structures of different morphologies.
- Development of a new way to fabricate electrically conductive ceramic/carbon composites with ordered structures
- Study of the densification of ceramic/carbon composites by spark plasma Sintering SPS. This technique allowed the fabrication of nacre-like brick-and-mortar structures composed of ceramic bricks separated by thin carbon layers without degrading the materials.
- Study the effect the ‘soft phase’ in the fracture behavior of bio-inspired composites using in-situ mechanical testing.
- Development graphene complex cellular networks of tunable physical properties and their exploration as efficient platform for the fabrication of mechanically robust, electrically conductive, self-healing and sensitive skin-like nanocomposites.
The discoveries resulted from this project reveal novel manufacturing and bio-inspired materials design concepts that can have a large social and economical impact by enabling cleaner and more efficient technologies. For example, these materials will help to develop novel high performance multifunctional systems for efficient production and transport of energy, longer lasting implants and electronic skin.