Abstract
Natural structural materials like bone and shell have complex, hierarchical architectures designed to control crack propagation and fracture. In modern composites there is a critical trade-off between strength and toughness. Natural structures provide blueprints to overcome this, however this approach introduces another trade-off between fine structural manipulation and manufacturing complex shapes in practical sizes and times. Here we show that robocasting can be used to build ceramic-based composite parts with a range of geometries, possessing microstructures unattainable by other production technologies. This is achieved by manipulating the rheology of ceramic pastes and the shear forces they experience during printing. To demonstrate the versatility of the approach we have fabricated highly mineralized composites with microscopic Bouligand structures that guide crack propagation and twisting in three dimensions, which we have followed using an original in-situ crack opening technique. In this way we can retain strength while enhancing toughness by using strategies taken from crustacean shells.
Highlights
In order to improve the mechanical properties of materials their structure and architecture need to be carefully controlled at a range of scales from nm to cm
While the complexity of the structure of natural materials has been known for some time, the advent of AM could offer the level of microstructural control needed to produce artificial analogues, and there have been a number of recent attempts to achieve this[22,23,24,25,26,27,28,29]
The shear forces arising from extrusion have
Summary
In order to improve the mechanical properties of materials their structure and architecture need to be carefully controlled at a range of scales from nm to cm. We use robocasting to produce a range of complex ceramic/polymer composite systems based on aligned alumina platelets.
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