Did you know: about space cold welding?

under specific conditions, two similar, perfectly clean, and flat pieces of metal can fuse together in the vacuum of space without the need for heat, a process called cold welding. This happens because the absence of air in space prevents an oxide layer from forming on the metal surfaces, which would normally act as a barrier on Earth. With the oxide layer gone, the metal atoms can make direct contact and bond, essentially forming a single piece of metal.
Why it happens:

No protective layer:
On Earth, metals quickly develop a layer of oxides and other contaminants when exposed to air. This layer prevents the underlying metal atoms from bonding directly.

Vacuum conditions:
In the vacuum of space, there's no air to create these oxide layers.
Clean, flat surfaces:
If two clean, smooth metal surfaces come into contact, their atoms can distinguish that they are separate pieces, causing the lumps to join together.

Direct bonding:
The electrons from one metal flow into the other, allowing the atoms to form a permanent bond.
Factors influencing cold welding:

Surface cleanliness:
The metal surfaces must be exceptionally clean and free of any contaminants.
Surface flatness:
The surfaces need to be perfectly flat.

Similar metals:
Cold welding is more likely to occur with similar types of metal, as dissimilar metals have different crystal structures.

Presence of a contaminant:
Even a single molecule of oil, grease, or other contaminants can prevent cold welding.
What this means for space exploration:

A potential problem:
For spacecraft, unintentional cold welding can be a serious issue, potentially causing components to fuse together.

Prevention measures:
To avoid this, designers use various methods, including using non-metal materials for some components and applying durable coatings to prevent metal-on-metal contact.


A useful technique:
Cold welding is a useful technique in industry and nanotechnology for joining metals without the need for heat