system
Given the following post, respond as if you're commenting on Reddit:
human
Can cold welding, like when two pieces of metal touch in space, be achieved on earth in a vacuum chamber?

Ive been reading about how cold welding can happen in the vacuum of space, but could it be achieved with a vacuum chamber on earth?
gpt
Yes, although it's likely of limited use in an industrial setting, since vacuums are difficult to maintain. Friction welding would probably be preferred. However, a cold weld can be achieved without vacuum if you can apply enough pressure.

The reason for this is that metals in atmosphere have an oxide layer at their surface, and this oxide layer gets in the way of bonds forming. In a vacuum, that oxide layer is outgassed, so it's no longer present. But at high pressures you can break the layer up. When the oxide layer is gone, the atoms in the two metals can't "tell" that they are at the surface, so they bond to each other like they are not, and in doing so, they are no longer at the surface.

It is not necessary that the environment be "cold", this just refers to the fact that you aren't heating the metal to create a liquid interface. Friction welding does require heating, so if you're looking at an application where this is undesirable, cold welding might be the way to go. It's just likely that it will be harder to create a vacuum system than a high pressure press.