On Jun 29, 3:47*pm, Stanley Schaefer wrote:
On Jun 29, 6:48*am, George Herold wrote:

(reposted from SED)
I want to try soldering some aluminum plate (0.032”) onto each side
of
a brass cylinder. *When trying to solder aluminum in the past I
failed. *I think I heard that some Al alloys are easier to solder
than
others. *I’ve got a choice (From McMaster-C) of 6061, 2024. 7075, and
1100. * Any idea of which is better?

I was also planning on getting some aluminum flux and some Zn/tin
solder from McM-C. *Other suggestions welcome.

Thanks

George H.

It IS possible, but you have to use something to scratch through the
oxide coat first to bare aluminum. *Usual practice is to puddle the
solder on the aluminum and use a stainless brush through the molten
solder until the surface is tinned, then sweat the other piece to it.

Yeah, I figured I'd tin both sides and then mash 'em together..
(not sure exactly how to do the mashing, from center out at least.)

I never thought (or heard) of brushing it while under the solder,
Thanks!
My Alcoa book suggests that the high zinc-content solders work the
best, another one recommends almost pure tin, go figure. *Fluxes
usually have some really active content to dissolve the aluminum oxide
and will result in severe corrosion if not removed/neutralized.

Yeah.. been there with some SS fluxes. Should be fine if I can tin it
all nicely.


If there's significant stress and it's a butt joint, you may have
cracking and joint failure. *In that case you might need some
redesign, like going to solder tabs on your plates and maybe a thin
aluminum shrink-fit tube over your brass to solder to.

Well if solder doesn't work, then maybe some Al 'loaded' epoxy will,
'be the ticket'.


Stan

Thanks again Stan,

George H.