Lunar Aluminum & Titanium

[Rhyshaelkan]

Being a welder/fabricator. I find the coincidence amazing that the two most common construction metals on Luna, and the most probable construction method all work well together.

Mild steel does not like to be electron-beam welded. As it is done too fast and you will get resulting cracks due to the uneven heating/cooling. However aluminum and titanium or an alloy of both prefer to be welded with electron-beam welding. In addition electron-beam welding needs to be performed in vacuum. Of which the Lunar surface has an abundance. Truly a win on all counts.

[Sam Fraser]

Hello, Rhys. Your background in welding automatically promotes you to the most knowledgeable in the field here! :cool: Yes, aluminium and titanium are two very useful and abundant metals in lunar regolith. What would some of the first products be from these two materials? Shielding for crewed exploratory or mining vehicles to NEOs? Trusses for a prototype solar power satellite? Something even simpler and more near-term?

[Rhyshaelkan]

Not to go off-topic, from myself even :D However, the silicon by-product of refining such metals could be used to make the solar panels of SPSs. To recoup money spent on the venture I do think building trusses for an SPS or ten would be the way to go.

I enjoy welding but I think robots can do it better ;) As good as a man is he will never have the steady hands of a robot, and constant smooth motion = a better weld.

The mechanical strengths of aluminum and titanium will work just fine on Luna or in the micro-gravity of orbit. Alloy compositions of the main metals that can be harvested from Luna, Ti, Al, Fe, Mg, Ca, will be an ongoing research. The crystal structures of the alloys could grow in an entirely unique pattern in the low-g of Luna or in the micro-g of orbit. Possibly allowing such unique materials to be produced as ceramets.

Again, not to get off-topic, but Luna's lack of atmosphere does nothing but help the production of metals. A chronic problem of welding on Terra is the inclusion of gas atoms. This will not be the case with welding on Luna or in orbit. Pristine bonds can be created in vacuum with the electron beam process.

Vacuum is a great insulator. Once the titanium or titanium alloy is refined and extruded as a structural member, cut off at regular lengths. Then it can slowly cool in the heat of the sun.

[Rhyshaelkan]

After I think about it though. We would most likely be sending up the smallest of solar-furnaces and metal processors.

Things to research: milling machines that will deal with no lubrication, or an alternative form of lubrication. I was thinking of using Lunar oxygen at the point of cutting to help cool while milling. However, titanium and aluminum would oxidize. Not any more than on Terra though. At least the smelting, forming, and welding of Al and Ti will be done in vacuum.

I am thinking ceramic rollers to support the cooling metal while it is rolled to size. In vacuum, ultra pure aluminum will weld itself to other metals if care is not taken.

Mirrors for a larger furnace might be the first thing desired to be built.

Sintered rollers out of Lunar regolith might be the way to go. Shape them on a lathe. Depending on the capabilities of the 'bots sent up, human presence will not be required for some time. However when aluminum coated calcium wire is being wound for new motors on Luna, perhaps then a human touch will be needed.

The sooner the tether can be cut from Terra the better. Ultimately one of the first things to be produced from Lunar soils will be LOx and powdered aluminum. Thus the first OTV can start taking shipments back and forth to LEO. That way we can get maximum use out of a F9 rocket.

[Alexander Declama]

How do you avoid unwanted vacuum welding

[Rhyshaelkan]

For the holding, bending, rolling, etc. tools. Use non-metal elements for such. High-temp plastics. Non metal ceramics is what I had in mind when I thought of the tools to process metals harvested from Luna.

The abilities of metals to self-weld to each other is cool, when wanted. A huge issue if it happens when you do not want it. The ultra purity you can achieve in vacuum is a boon. However it is oxygen you need to mainly avoid. Oxygen bonds to near everything given the chance. So an inert gas environment would be best. Nitrogen, argon. They would work best for a manufacturing atmosphere.

Refine your metals in vacuum to achieve ultra-purity. Then process those metals in an inert atmosphere.