Definition - What does Cold Welding mean?
Cold welding is a bonding process during which two solids are forced to form a single piece by applying adequate pressure. This disrupts the barriers of the oxide layers on the interface, and brings about an enduring adhesion between the two surfaces.
Unlike the conventional welding process, there is no application of severe heat or melting of the material at the interface. Both the surfaces continue to remain in solid phase throughout this forced adhesion process. The necessary force for the adhesion is applied through mechanical rolls and dies.
Cold welding is also known as contact welding.
Corrosionpedia explains Cold Welding
When two surfaces without an interposing oxide layer are brought together, the similar atoms of either side collapse into each other.
Cold welding as a joining technique has some limitations. The joint can fail in a reactive environment or a high oxygen environment. It is suitable for buried pipes and for components deployed in spaces where there is no risk of oxygen contact. For the cold welding to be effective, the surfaces need to be brushed and cleaned effectively.
If the outer layer of any one of the components has high oxygen content, adhesion is unlikely to occur. Another critical factor is the malleability of the metals used. At least one of the two metals to be joined must be malleable.
Unintended cold welding, causing welding of separable contacts, was discussed as a mechanical issue in some of the early satellites. Cold welding concepts are used in nano and micro fabrications in high-technology areas. For example, a gold nanowire can be cold welded instantly. The technique is also used in the nuclear field.