Metallic foams have enormous potential for applications requiring both light weight and high strength and stiffness. Titanium’s low density and excellent mechanical properties make it particularly interesting for foamed or porous structures. Freeze-casting is an ice-templating technique involving the solidification of particles suspended in an aqueous solution for the creation of a porous structure. When solidifying in a thermal gradient, ice dendrites grow directionally while rejecting titanium particles into the liquid interdendritic spaces. Upon removal of the particle-free ice dendrites, pores are formed. When unidirectional freezing techniques are employed, the dendrites (from which pores are created) are elongated and aligned. This unidirectional freeze-casting technique offers more control over foam architecture than possible via traditional solid-state processes. Freeze-cast titanium foams exhibit high specific strength and stiffness, high energy absorption, and excellent corrosion resistance, making them ideally suited for applications within the aerospace industry. The simplicity of the freeze-casting technique—and the employment of water as a solvent—enables scalable and low-cost production of this material. This research serves to utilize a microgravity environment to demonstrate the feasibility of freeze-casting as a space-based manufacturing method for producing near net-shape structural materials. Additionally, knowledge gained from this research advance the manufacturing of lightweight materials by improving a low-cost, scalable technique for the fabrication of titanium foams with desired architectures. Freeze-casting has the potential to produce porous products with a specific porosity/microstructure, including near net- and complex shaped products, provided that formation and growth of ice dendrites is appropriately controlled. Freeze-casting porous titanium structures in microgravity will improve our scientific knowledge beyond what is possible through terrestrial based research, which will improve our understanding of gravitational effects on suspension settling before and during ice solidification, and thus enable optimized fabrication of a large variety of light-weight materials and structures, on earth and in orbit.
|Effective start/end date||4/25/15 → 10/24/16|
- NASA Neil A. Armstrong Flight Research Center (NNX15AJ84G)
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