Viscous Liquid Foam - Bulk Metallic Glass (Foam) - 07.14.16
This investigation tests and produces hardened foam from bulk metallic glass. The absence of gravity facilitates the creation of a more uniform metallic glass foam, a material with an extremely high strength to weight ratio. Developing lighter and stronger materials can lead to a more durable spacecraft that will require less propellant to travel long distances. Science Results for Everyone
Have foam, will (space) travel. Microgravity makes it possible to produce metallic glass foam with an extremely high strength-to-weight ratio. Spacecraft made of such light, strong material would be more durable against space debris, yet require less fuel. This experiment studied the formation of metallic foam from bulk metallic glass, a type of metal alloy that solidifies without crystallizing, and demonstrated foaming an expandable structure in microgravity and a vacuum. Researchers examined the physics of bubble and foam formation in microgravity and found that foam created on the ground and aboard the Space Station had similar textures. Experiment Details
William L. Johnson, Ph.D., California Institute of Technology, Pasadena, CA, United States
Marios D. Demetriou, Ph.D., California Institute of Technology, Pasadena, CA, United States
William F. Kaukler, Ph.D., University of Alabama at Huntsville, Huntsville, AL, United States
Chris Veazey, California Institute of Technology, Pasadena, CA, United States
NASA Marshall Space Flight Center, Huntsville, AL, United States
Sponsoring Space Agency
National Aeronautics and Space Administration (NASA)
Human Exploration and Operations Mission Directorate (HEOMD)
ISS Expedition Duration
April 2004 - October 2004
This experiment has not flown before, however, research on earlier Shuttle flights helped develop methods for better creating bulk metallic glasses.
- This experiment is designed to test the ability to study the formation of a metallic foam from a bulk metallic glass which is a type of unique metal alloy that, when cooled from a liquid to a solid at high cooling rates, solidifies without crystallizing.
- By creating a bulk metallic glass foam in space, researchers will also study the physics of bubble and foam formation in microgravity. Furthermore, this experiment will demonstrate foaming an expandable structure under microgravity and a vacuum.
- Because the effects of buoyancy are minimized in space, more uniform foam structures with unique properties can be produced. These new materials have potential applications for use in future Moon or Mars space structures (due to their high strength and low weight) as well as potential shielding against micrometeorites and space debris impacts in space.
Bulk metallic glasses are a special class of metallic materials created by rapid solidification that causes them to form glass-like structures that are light but very strong. This experiment investigates the formation and structure of foams made from bulk metallic glass. Because the effects of buoyancy are minimized in space, more uniform foam structures with unique properties can be produced. These new materials have potential applications for use in future moon or Mars space structures (due to their high strength and low weight) as well as for potential shielding against micrometeorites and space debris impacts on spacecraft.
Hardened bulk metallic glass foam may be very useful as a material for building future spacecraft for long-term space flight. The foams can also be used to build permanent structures on the Moon or Mars. Buildings and spacecraft fuselages made from bulk metallic glass foams can be extremely tough and light at the same time, thereby reducing costs while increasing the protection they provide to explorers.
Bulk metallic glasses are extremely strong materials (2-3 times stronger than conventional metals) that, when molten, are viscous enough to make well-constructed solid foam. While bulk metallic glass is strong, it is also brittle. A bulk metallic glass foam is very resilient, however, much like spongy human bone. Solid foams are the best materials to make large, stiff structures due to their high strength to mass ratio. Foaming also considerably increases a material's ability to act as a temperature insulator. Foam can be difficult to study on Earth because gravity can interfere with bubble formation, causing the bubbles to rise and the liquid to sink. This is especially true when conventional metal liquid (like aluminum or titanium) is foamed. A better understanding of foaming will help investigators improve a variety of materials used in everything from medical supplies to industrial processing, sports equipment and military vehicles.
Operational Requirements and Protocols
Conducted inside the ISS Maintenance Work Area. Three small copper ampoules filled with samples of bulk metallic glasses will be processed.
Crew members will fit ampoules onto the end of the ISS soldering iron, causing the bulk metallic glass samples to foam. Samples will be heated for three different lengths of time to assess degree of foaming and returned to Earth for later analysis.
Decadal Survey Recommendations
Information Pending^ back to top
Three planned runs for the Foam experiment were successfully completed on station during Expedition 9. Samples, were returned to Earth in late August 2005, have been analyzed and reported (see Veazy, et al. 2008). The experiment was designed to test the hypothesis that amorphous metals exhibit foam-making qualities on the ground that mimic metallic foam textures made in microgravity conditions. The amorphous metals, when softened or melted, have a super-cooled state that has a very high viscosity - ideal conditions for foam processing. Foam made from a Pd40Ni40P20 glass-forming metallic liquid, was made both on the ground and aboard the ISS. Pellets of the material that contained 1-atmosphere bubbles, were sealed in ampoules. The ampoules were made to thread into a soldering iron tip for heating aboard the ISS. The samples were heated at 360 C for 5 minutes, enabling foam creation, then allowed to cool. The ground samples contained textures that were similar to those produced in microgravity - equally distributed bubbles dominated by surface tension forces; the bubbles did not experience sedimentation (floating).
These types of foams have great potential for future exploration applications because of their great strength and light weight. In particular, such foams may make very effective shields against micrometeorite and orbital debris strikes. (Evans et al. 2009)
Veazey C, Demetriou MD, Schroers J, Hanan JC, Dunning LA, Kaukler WF, Johnson WL. Foaming of Amorphous Metals Approaches the Limit of Microgravity Foaming. Journal of Advanced Materials. 2008; 40(1): 7-11.
Hofmann DC, Roberts SN. Microgravity metal processing: from undercooled liquids to bulk metallic glasses. npj Microgravity. 2015 May 27; 1: 15003. DOI: 10.1038/npjmgrav.2015.3.
Ground Based Results Publications
Schroers J, Veazey C, Johnson WL. Amorphous Metallic Foam. Applied Physics Letters. 2003; 82: 370.
Brothers AH, Dunand DC. Syntactic Bulk Metallic Glass Foam. Applied Physics Letters. 2004; 84(7): 1108-1110.
NASA Fact Sheet
NASA Image: ISS009E1479 - Expedition 9 Science Officer Mike Finke performing the Foam experiment in the Maintenance Work Area on the ISS.
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NASA Image: ISS009E14583 - Foam investigation setup in the Maintenance Work Area on ISS during Expedition 9.
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NASA Image: ISS009E14593 - Close up image of the Foam investigation on ISS Expedition 9.
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