Re: [amsat-bb] joining galvanized metal

[RogerKola@xxxxxxx]

na9d-2@speakeasy.net said:

>>>There's some stuff you can do.  There's a guy at Dayton every year that
sells these low temperature welding sticks that you can do with galvanized
metal.  I think all you have to do is brush off some of the surface and prep
it.  I know these will work on aluminum but I think they'll do galvanized
metal.  I have his info out in the garage and can send it to you if you
like.<<<

As a quasi-metallurgist in both the steel and aluminum industry, I have to 
mention that Zinc (which is your galvanizing of course) has a lower melting 
temperature than steel, the base metal. Any joining process has to take into 
account the removal of the "protective" Zinc layer by heat and how much of 
the protective coating you desire to remain intact. Anything that melts the 
zinc to effect a bond is going to be suspect in leaving the base metal and 
bonding material exposed.

Some industrial solutions to this dilemma include; overlap of the joints, 
welding the interior seam and sealing the outer, exposed seam.  Cold spray 
galvanizing is a consideration for exposed steel, though not very much 
integrity is guaranteed, painting or epoxy sealing of the seam is a 
possibility also.

Zinc melts at 785 degrees F and Lead at approx 650 degrees F. A careful 
soldering experience may prove useful, a physical lockseam filled with solder 
might be better if full "roundness" is not required.... solder would also 
cover the exposed cutting edge which is typically only covered 40% by the 
"rollover" of zinc during the cutting process.

Then again...how long will you be exposing it to weather?...next I'll have 
you doing salt-spray tests...sorry


Roger
WA1KAT
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