Cold Welding?

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What is cold welding?

"Cold welding is a bonding process where two items are combined into one through means 

of intense pressure that is applied by dies and rolls. As the name implies, this technique 

does not rely on heat to change the state of the items being bonded—these substances 

remain in a solid state throughout the procedure. Not all metals make ideal candidates for 

cold welding due to the oxygen content within their outer layers, and even after extended 

brushing and cleaning, the metals will not bond if one of them is not malleable. Likewise, if 

the two bonded pieces are later exposed to an oxygen-rich environment or certain other 

reactive compounds, the cold weld will fail. Due to these limitations, the process of cold 

welding is most suitable for objects that will be deployed outside of the earth’s atmosphere, 

such as satellites or spacecrafts."

Read More: http://www.wisegeek.com/what-is-cold-welding.htm