Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

Re: cold weld between polished surfaces



At 11:01 AM 9/29/2004, you wrote:
What are the list-members' opinions on the rate at which two
highly-polished metal surfaces will cold weld to each other. Take the
surfaces to be smooth and free of contaminants. What time frame is
required for the surfaces to bond sufficiently well that when placed
under tension a fracture occurs NOT at the weld joint?

I was asked and could not confidently state a time frame. Any
constructive thoughts are appreciated.

Kenny Stephens
kstephens@hsutx.edu


Plausible? probably: probable? possibly: possible? undoubtedly....

If by cold weld we imagine two room temperature steel blocks of
nearly plane and smooth surfaces being wrung together, we may imagine
the mechanism to be hot deformation and welding of the plastic
tips of the adjacent asperities. This would imply that there are areas
which are not effectively joined, so we would expect the parting surface
to be somewhat weaker than the substrate.

A material such as steel is not thought to cold flow significantly, so
that time-dependent adhesion would seem unlikely.

There is another ball-game that happens when clean surfaces are pressed
together in high vacuum however.



Brian Whatcott Altus OK Eureka!