The Effect of Microgravity on the Oxidation of Iron Exposed to a Saltwater Solution

The Effect of Microgravity on the Oxidation of Iron Exposed to a Saltwater

Solution

Griffin Eslinger and Alexander Puckhaber

Co-Principal Investigators

Palmetto Scholars AcademyNorth Charleston, SC

Description of ExperimentOur experiment compared the structural integrity of an iron bar oxidized in the presence of saltwater in microgravity to an iron bar oxidized in the presence of saltwater on Earth.

Hypothesis 

We predicted that the iron bar oxidized in microgravity would be weaker than the iron bar oxidized on Earth. Without gravity, the surface tension of the salt water will be relativelystronger. Stronger surface tension in microgravity might make the oxidation process happen at a faster pace.

Why this is Important If we find that the iron bar oxidized in microgravity is significantly weaker than the iron bar oxidized on Earth, our findings could impact how engineers design space missions.Many pressurized spacecraft are built with iron alloys. There would most likely be oxygen and water on the inside. If rust in microgravity causes iron to become weaker than expected, there might be a high potential for catastrophic failures.

Materials Experiment Materials1. Type Two FME (Fluid Mixture Enclosure)2. 3.5% salt water solution3. Iron tensile testing bar (9.5mm by 75mm by

2mm)

Testing Materials4. Tensile testing machine5. Scanning electron microscope

Methods 1. 5 identical FMEs

prepared and numbered (+2 old FMEs)

2. One (Sample #2) randomly selected to go to ISS

3. Sent up for 9 weeks in space as part of SSEP Mission 4

4. Upon return, tested at University of South Carolina Mechanical Engineering Department on a Tensile Testing Machine.

5. After tensile testing, surface examined under scanning electron microscope at NOAA lab.

Tensile Testing• Five properties measured

o Modulus of Elasticity (Young’s Modulus)o Yielding Strengtho Maximum Strengtho Elongationo Ductility

Tensile Results

Scanning Electron Microscope

Space sample had small circular rust spots. Controls had larger plate-like rust patches.

Space Earth Control

Scanning Electron Microscope

The controls had a rougher surface (more rusting) and a thicker breaking cross section

Space Earth Control

Summary

• The Iron bar that went to space:o Yielding Strength: Averageo Elongation: Averageo Maximum Strength: 2nd highesto Modulus of Elasticity: Averageo Ductility: Highest

But none statistically significant

• SEM showed less rust and in a different pattern.

• Hypothesis: false, bar not weaker

Acknowledgments

Partners• Space and Naval Warfare

Systems Command (SPAWAR)• Center for the Advancement

of Science in Space (CASIS)• National Center for Earth and

Space Science Education• College of Charleston• Medical University of South

Carolina (MUSC)• National Oceanic and

Atmospheric Administration (NOAA)

Sponsors• ISHPI• Google• CASIS• Palmetto Scholars

Academy Board Members

• Palmetto Scholars Academy Families

Thank you to the Partners and Sponsors who made this experiment possible:

Questions?

Closeup of Stress vs Strain Curves