Iron-Basalt Pressure Hull Components

Combining a thin layer of cast basalt to a much thicker layer of cast basalt might solve several issues with habitat hull components.

This idea is still very conceptual. And I’m not really working on it at the moment. I just wanted a place to park it for now. Let me know if you have any ideas or suggestions. Links to data/research would be even better.

Concept

1. Pour molten basalt (that has been stripped of oxygen, iron, and anything else we need) into a mold.
2. Set cooled and formed iron (may or may not need to be steel) sheet on top of the molten basalt.
   1. The iron sheet has “spikes” that will secure it firmly to the basalt.
3. Let everything cool. Design the molds so that heat can be extracted to provide electricity and speed cooling.
4. Pull from mold and repeat.

Data

Physical properties

• Melting points
  • Iron – 1538 °C / 2800 °F [1]
  • Steel – 1425-1540 °C / 2600-2800 °F [1]
  • Basalt
    • 984°C to 1260°C [2] (not specified so I assume at 1 standard atmosphere)
    • 1000^oC to 1200^oC (1832^oF to 2192^oF) [3] (not specified so I assume at 1 standard atmosphere)
    • 1095℃ – High-Ti Lunar basalt at low pressure (0-1 bar) [4, pg 206-207]
    • 1408℃ – Very low-Ti Apollo 15 green glass at low pressure (0-1 bar). [4, pg 206-207]
    • Melting temperature could be 100℃ higher than Earth basalts due to the lack of Lunar H2O [4, pg 206]

Advantages

These are just guesses at the moment:

• It might be easier to seal the habitat and make it pressure tight by simply welding the iron layer of one component to the iron layer of another instead of figuring out how to seal basalt to basalt.
• The layer of iron might be a better barrier to nitrogen and oxygen than basalt.
• It might be easier to repair and maintain iron than basalt.
• It might be easier to lock the components in place (to maintain a more rigid structure) through component design AND welding the iron together. We can also design the component to bolt together as well (we’d have to fabricate the bolts though).
• The external basalt might be better able to deal with the abrasive regolith and mega-regolith surrounding the pressure hull. Less maintenance.
• The internal iron lining might be easier to paint/decorate.
• It will be easier to weld on attachment points and other additions to the iron layer than the basalt.
• We could also look into pounding basalt fiber between the gaps of the components to help seal it up before welding the iron.

Disadvantages

These are just guesses at the moment:

• It will require more processed iron than a simple basalt solution.
• More complicated design and process
  • Will have to fabricate the iron layer AND the basalt layer.
• I don’t know how well the iron and basalt will play with each other. How durable will it be? How much weight/force/vibration can the spikes take before they pull out? How much damage will pulling the spikes out do and how would we repair it?
• Is it even basalt once we’ve stripped out the elements we want? And what properties will this material have?

Images

Resources (used)

1. American Elements (www.americanelements.com/meltingpoint.html)
2. American Mineralogist (www.minsocam.org/msa/collectors_corner/arc/tempmagmas.htm)
3. National Geographic Encyclopedia – Magma (www.nationalgeographic.org/encyclopedia/magma/)
4. Lunar Sourcebook: A user’s guide to the moon. Grant H. Heiken, David T. Vaniman, Bevan M. French. 1991. [www.lpi.usra.edu/publications/books/lunar_sourcebook/]. Last checked Feb 25, 2019.

Resources (not read yet)