On Earth when two pieces of metal comes into direct contact with each other, nothing amazing happens. In a complete vacuum condition the two metals fused permanently, how and why?
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The Feynman quote on the Wikipedia page for cold welding pretty much explains it. – ACuriousMind Apr 07 '15 at 14:42
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What is your source? I suppose that it happens if the two metal surfaces are without oxide films. So even in vacuum the surfaces have to be clean from oxidation. – HolgerFiedler Apr 07 '15 at 14:53
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I was browsing a children magazine about astronomy and chanced upon an interesting article mentioning this phenomenon. – user6760 Apr 07 '15 at 15:01
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Related: http://physics.stackexchange.com/q/87107/2451 – Qmechanic Apr 07 '15 at 15:12
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In theory, yes – it’s an effect called ‘cold welding’ by which the metallic bonds that hold atoms together in each object effectively ‘bridge the gap’ between them to create a single solid object. In practice, this rarely happens on Earth because most metals form a protective oxide layer where their surface is exposed to the atmosphere. Slight bumps and irregularities in metallic surfaces also prevent this from happening. Even when metals are taken into space, the oxide layer remains – but, of course, if you deliberately polished it off then, yes, the two metals would fuse together, and that’s something satellite and spacecraft designers need to bear in mind.
