NSF Award
2423536
When solutions or solutions that contain particles are frozen on Earth, particle settling and liquid motion due to gravity affect the structure of the resulting solid. By freezing these solutions in microgravity condition, the subtle forces involved in growing the solvent crystals and forming particle-assemblies between those crystals will be revealed. The experimental setup on board the ISS will provide an ideal environment for imaging crystal growth and particle motion under strictly controlled conditions. Comparing the structural features obtained on the ISS with those on the Earth will reveal the mechanisms of structure formation that are obscured by gravity. Combined with computational models, the proposed research will help designing new materials as well as improving both the structure and properties of existing ones for applications in biomedicine, catalysis, water purification, and energy generation and storage. This award is ideally suited for the integration of research and teaching in STEM educational programs that incorporate space themes to increase interest and diversity, and to improve skills in K-12 STEM education.<br/><br/>The fundamental knowledge gained by performing structure formation studies on the ISS and Earth will be of interest to both the freeze casting and the directional solidification communities. To date, only few short duration (25 seconds on a parabolic flight) microgravity freeze casting experiments have been performed. This study is the first to analyze and quantify complex dynamics and interactions of directional crystal growth and particle self-assembly, in the presence and the absence of gravitational forces, and with an externally applied magnetic field. The complementary set of experimental and simulation results will enable a more systematic exploration of currently unpopulated spaces in material structure and property. Two complementary approaches will be pursued: i) ex situ and in situ observations and quantification of the freeze casting process, and analysis of the morphology of ice-templated materials manufactured in microgravity and in terrestrial under well-defined and controlled conditions; and ii) the development of simulation techniques using the experimentally determined input data to enhance the predictive capability of freeze-casting models for fabrication of critical materials in Space and on Earth. The new experimentally validated, model-based tools will enable the science-based design and manufacture of new materials.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
