Cold welding

It was then discovered that two clean, flat surfaces of similar metal would strongly adhere if brought into contact while in a vacuum (see Van der Waals force).

In 2009 the European Space Agency published a peer reviewed paper detailing why cold welding is a significant issue that spacecraft designers need to carefully consider.

One source of difficulty is that cold welding does not exclude relative motion between the surfaces that are to be joined.

Unlike cold welding process at macro-scale which normally requires large applied pressures, scientists discovered that single-crystalline ultra-thin gold nanowires (diameters less than 10 nm) can be cold-welded together within seconds by mechanical contact alone, and under remarkably low applied pressures.

[2] High-resolution transmission electron microscopy and in-situ measurements reveal that the welds are nearly perfect, with the same crystal orientation, strength and electrical conductivity as the rest of the nanowire.