[TowerTalk] Cadweld Question

Roger (K8RI) K8RI-on-TowerTalk at tm.net
Tue Jul 31 21:30:21 EDT 2007




> At 02:20 PM 7/31/2007, Mark Robinson wrote:
>>I was looking at the Cadweld procedure and was wondering if it is possible
>>to use my oxy-acetylene torch to heat up the cadweld material instead of
>>messing with pyrotechnic chemicals.
>>
>>What is the base material that they use to join the rod and copper wire?
>
> copper.
>
> It's a thermite reaction.. powdered aluminum and copper oxide reacts
> to form aluminum oxide and copper with a lot of heat.
>
> You could probably just braze it with any sort of reasonably high
> conductivity rod (moderate silver content), or, heck, if you can
> figure out what sort of flux to use, copper rod.. it's just welding
> (where welding is defined as joining using a weld metal that is the
> same as the parent metal being bonded)

Welding copper is an interesting exercise due to the high thermal transfer 
as well as oxidation. It takes a lot of the right kind of flux. I don't 
know, but would guess the same flux used for brazing might work. OTOH 
melting coper into steel which has a much higher melting point probably is 
for the experienced welder. More than likely flux used for silver solder 
might work as well, but silver solder is a lower temperature.
73

Roger (K8RI) 



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