Strong, Tough Porous Materials via Freeze Casting
Graduate Student: Noriaki Arai
It has been known that natural materials such as nacre and bone exhibit significant strength and toughness due to their sophisticated hierarchical structures. These mechanical properties come from not only the properties of constituents (i.e. brittle minerals and organic materials) but also their designs to induce strengthening and toughening mechanism which span multiple length scales. Thus, understanding those mechanisms and mimicking them are the promising route to fabricate synthetic materials with unprecedented mechanical properties.
Porous materials have been researched extensively since there are a wide range of application such as filtration, energy storage, insulation and biomaterials. However, the pores are considered as defects so possessing porous feature while maintaining sufficient mechanical properties has been challenging. Freeze casting is considered as a potential method to translate biological microstructures such as lamellae roughness and inorganic bridge of nacre into synthetic materials to enhance the mechanical properties in addition to the ability to tailor pore characteristics (i.e. porosity, pore size, pore alignment and pore shape).
In this study, we aim to develop novel freeze casting method which creates hierarchical pore structure with the goals to achieve strong, tough, porous materials. For example, our novel freeze casting method is able to create inorganic bridges and surface asperities which enhance the strength of porous materials. We will evaluate the pore characteristics and its functionality of materials as well as their mechanical properties.
SEM of sample produced via double freeze casting.