GIF of cold welding of two gold nanowires.
https://diqn32j8nouaz.cloudfront.net/cold_welding.gif
https://diqn32j8nouaz.cloudfront.net/cold_welding.gif
During cold welding, metals can join without heat, by mechanical contact alone. It can happen with clean, flat surfaces of similar (but not necessarily identical) metals, under vacuum. We first discovered cold welding in the 1940s.
Interestingly, cold welding is problematic in space travel. Cold welding is usually prevented by the various contaminants and oxides present on metal surfaces. However, the absolute vacuum of space eliminates these, leaving two perfectly clean metal surfaces. This was notably brought to attention after studying an incident in 1991, during which an antenna attached to the Galileo spacecraft failed to open.
https://diqn32j8nouaz.cloudfront.net...d_welding1.png
https://diqn32j8nouaz.cloudfront.net...d_welding2.png
https://diqn32j8nouaz.cloudfront.net...d_welding3.png
