Cold welding refers to the process of joining two bodies of metal (sometimes different) without temperature effects in the joining area. What is the difference between cold metal welding from conventional welding? There is no need to melt the metal. For the first time, scientists drew attention to the process of combining metals to cold in 1940. It was noticed that in a vacuum there is a mutual effect of two metal pieces on each other: if their surfaces are flat and clean, then they are attracted. Nowadays, scientists are exploring the possibility of applying this welding method at the nano and micro levels. If the connection is made of small-sized parts that are soft, thin and plastic, then it is very advisable to use this method.
Today it has been proven that with strong compression, a reliable connection of two metal parts is obtained. The quality of the joint can be improved both by extending the time of application of the compressive force and by increasing the heating time of the parts to be joined. Today it is known that there is no such thing as a perfectly smooth metal surface. This means that two metal parts touch each other at the top points of their surfaces. In the process of joining together, a small part of the metal surface is involved. However, these small areas provide fairly reliable cold welding of metals.
Metal, being in contact with oxygen or other reagents (substances), is covered with a layer on its surface, which leads to deterioration or impossibility of cold bonding of metals. The oxide layer formed on the metal surface (air contains oxygen) does not allow metals to be joined under normal conditions. It is known that even if the metal is placed in a vacuum, the oxide film does not disappear. It can be concluded that the surfaces to be joined must be thoroughly cleaned before cold welding.
Some fun facts:
1 . Scientists have proven that it was with the help of the cold welding method that nuggets of gold appeared in nature. No oxide film forms on gold. Gold does not undergo oxidation.
2 . During the first launches of Earth satellites, if any problems related to the strength of the joints appeared, the cold welding method was blamed for everything. A little later, it became clear that it was simply necessary to refine some design solutions. Scientists to this day have not established the facts of problems in orbit as a result of poor-quality joining of metals by cold welding.
