Microgravity Fabrication of Freeze-cast Titanium Foams Testing

Freeze casting in microgravity is a novel materials-processing technique with the potential to provide scalable, affordable in-space manufacturing of materials and structures. Numerous advantages for space exploration include reduced launch costs and enabling transport of raw materials to build structures that would otherwise be too large to launch. Researchers surmised that terrestrial-based gravitational forces result in inferior titanium and titanium-oxide foams and that those created in microgravity-based freeze casting would have better pore alignment and order. Northwestern University’s parabolic flight tests aimed to verify this assumption. Flight tests in 2014 revealed that gravity had a substantial impact on the freeze casting results. Structures created in microgravity indeed exhibited far more desirable properties than those created on Earth. Subsequent testing in 2015 allowed the researchers to isolate other factors, such as convective fluid motion and sedimentation of particles in the titanium and titanium-oxide foams. Combining these observations helped them better understand the material’s properties in order to improve their process for longer duration testing. Northwestern University’s work with Flight Opportunities aided its selection for a 6-month NASA CubeSat mission. It has also been selected under the NASA Materials Lab Open Science Campaign for an International Space Station demonstration with an anticipated launch in 2019 or 2020.