Carbonyl

When Carbon monoxide gas is placed under pressure and heated, metals will 'dissolve' into the gas (or carbon monoxide liquid). Several carbon monoxide (CO) molecules will surround each metal atom. This is called a metal carbonyl. (Other forms of carbonyls exist, but this article is concerned with the carbon monoxide - metal ones.)

Note that carbon monoxide (CO) is a colourless, odourless, poisonous gas. Care must be taken that it does not leak into human habitation areas.

See this link, for the wikipedia page discussing them.

Use on Mars

On Mars this has two main uses. First, dust or ground soil can be placed in a carbonyl reactor. CO is pumped in, and the gas is pressurized and heated. Metal on the surface of the dust grains will form a carbonyl extracting it from the rock particles. By changing the pressure and temperature, different metals can be pulled out in succession. When heated, these metals in solution will decompose back to solids, making ingots of pure metal.

The second use is to have a carbonyl in a 3D printer, and use a laser beam (or other heat source) to decompose the carbonyl and leave behind a trail of pure metal. Layers will build up, giving us a 3D printed part. Such a 3D printer might well be inside the reaction chamber that formed the metal carbonyl in the first place.

If it proves to be possible to build a flexible reactor that can handle several different metals (and print 3D parts) this would be a very useful item to bring to Mars. However, such a device has not yet been built.

Types of metal carbonyls

• Titanium (surrounded by 6 CO molecules)
• Vanadium (surrounded by 6 CO molecules)
• Chromium (surrounded by 6 CO molecules)
• Manganese (surrounded by 6 CO molecules)
• Iron (surrounded by 5 or 6 CO molecules)
• Ruthenium (surrounded by 5 CO molecules)
• Nickle (surrounded by 4 CO molecules)

• Cobalt (2 cobalt atoms surrounded by 8 CO molecules, will form a carbonyl solid)