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Posted by on May 19, 2007, 9:01 pm
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I'm assembling some machined copper parts
for my rocket project. I'm using silver solder.
If I heat the parts hot enough to make the solder flow then
the parts get a scaly dark almost black coating.
On the exterior of the parts I can wire brish this away, but in the
interior passages I have some very fine (0.010") passages I don't want
to get clogged.
Does anyone know of a chemical method for cleaning this?
Does anyone know how to prevent it from forming?
I'm using a MAPP torch in normal air, I've
Contemplated getting a sand blasting box and converting it to an argon
purge box, then using an oxy acelelne torch to heat it, as the box has
no Oxygen.. I could also maybe put it in a purge box and heat with a
TIG torch.
Would the purge box help?
Am I better off just finding a furnace brazing shop?
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Posted by Phil on May 21, 2007, 9:15 am
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Other than removing the scale with some mechanical means such as the
sandblast or wire wheel that you mentioned , I don't know , would suspect
that there is some acid or chemical that should work , am wondering if you
used the proper flux and heat to attempt to silver solder your part , the
black that you describe would indicate a lack of silver flux on the part
before you attempted to solder , you will need enough heat to bring the
copper part up to a slight red color , if you don't have enough heat it will
take forever to get the temp. up and you will eventfully lose the effect of
the flux. Good Luck
> I'm assembling some machined copper parts
> for my rocket project. I'm using silver solder.
> If I heat the parts hot enough to make the solder flow then
> the parts get a scaly dark almost black coating.
>
> On the exterior of the parts I can wire brish this away, but in the
> interior passages I have some very fine (0.010") passages I don't want
> to get clogged.
>
> Does anyone know of a chemical method for cleaning this?
>
> Does anyone know how to prevent it from forming?
>
> I'm using a MAPP torch in normal air, I've
> Contemplated getting a sand blasting box and converting it to an argon
> purge box, then using an oxy acelelne torch to heat it, as the box has
> no Oxygen.. I could also maybe put it in a purge box and heat with a
> TIG torch.
>
> Would the purge box help?
>
> Am I better off just finding a furnace brazing shop?
>
>
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Posted by Grant Erwin on May 21, 2007, 5:29 pm
Please log in for more thread options Phil wrote:
> Other than removing the scale with some mechanical means such as the
> sandblast or wire wheel that you mentioned , I don't know , would suspect
> that there is some acid or chemical that should work , am wondering if you
> used the proper flux and heat to attempt to silver solder your part , the
> black that you describe would indicate a lack of silver flux on the part
> before you attempted to solder , you will need enough heat to bring the
> copper part up to a slight red color , if you don't have enough heat it will
> take forever to get the temp. up and you will eventfully lose the effect of
> the flux. Good Luck
>
>>I'm assembling some machined copper parts
>>for my rocket project. I'm using silver solder.
>>If I heat the parts hot enough to make the solder flow then
>>the parts get a scaly dark almost black coating.
>>
>>On the exterior of the parts I can wire brish this away, but in the
>>interior passages I have some very fine (0.010") passages I don't want
>>to get clogged.
>>
>>Does anyone know of a chemical method for cleaning this?
>>
>>Does anyone know how to prevent it from forming?
>>
>>I'm using a MAPP torch in normal air, I've
>>Contemplated getting a sand blasting box and converting it to an argon
>>purge box, then using an oxy acelelne torch to heat it, as the box has
>>no Oxygen.. I could also maybe put it in a purge box and heat with a
>>TIG torch.
>>
>>Would the purge box help?
>>
>>Am I better off just finding a furnace brazing shop?
I always heard you should use sulfuric, not hydrochloric (muriatic) for
copper-bearing workpieces, to clean soldering flux.
GWE
--
Posted via a free Usenet account from http://www.teranews.com
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Posted by whit3rd on July 2, 2007, 1:48 pm
Please log in for more thread options On May 19, 6:01 pm, P...@Rasdoc.com wrote:
> I'm assembling some machined copper parts
> for my rocket project. I'm using silver solder.
> If I heat the parts hot enough to make the solder flow then
> the parts get a scaly dark almost black coating.
Not sure if you really want to hear this, but... for our science lab,
we used a vacuum chamber and induction heater to do that kind
of thing, if it was critical. Silfos type silver solder is relatively
low temp, and is used on copper for refrigeration and the like, but
the result usually has copper oxide. Higher temperature silver
solders and long heat times just turn copper to oxide.
For some processes, there are 'anti-flux' coatings that don't wick the
melted material and which seal the surface; kind of a removable
paint. Maybe there's one for copper at brazing temperature?
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Posted by Andrew Mawson on July 2, 2007, 2:09 pm
Please log in for more thread options
> On May 19, 6:01 pm, P...@Rasdoc.com wrote:
> > I'm assembling some machined copper parts
> > for my rocket project. I'm using silver solder.
> > If I heat the parts hot enough to make the solder flow then
> > the parts get a scaly dark almost black coating.
>
> Not sure if you really want to hear this, but... for our science
lab,
> we used a vacuum chamber and induction heater to do that kind
> of thing, if it was critical. Silfos type silver solder is
relatively
> low temp, and is used on copper for refrigeration and the like, but
> the result usually has copper oxide. Higher temperature silver
> solders and long heat times just turn copper to oxide.
>
> For some processes, there are 'anti-flux' coatings that don't wick
the
> melted material and which seal the surface; kind of a removable
> paint. Maybe there's one for copper at brazing temperature?
>
The easiest one to come by and most effective that I've found is
Tippex typing correction fluid. The chalky deposit takes the heat and
the silver solder is effectively stopped by it.
AWEM
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> for my rocket project. I'm using silver solder.
> If I heat the parts hot enough to make the solder flow then
> the parts get a scaly dark almost black coating.
>
> On the exterior of the parts I can wire brish this away, but in the
> interior passages I have some very fine (0.010") passages I don't want
> to get clogged.
>
> Does anyone know of a chemical method for cleaning this?
>
> Does anyone know how to prevent it from forming?
>
> I'm using a MAPP torch in normal air, I've
> Contemplated getting a sand blasting box and converting it to an argon
> purge box, then using an oxy acelelne torch to heat it, as the box has
> no Oxygen.. I could also maybe put it in a purge box and heat with a
> TIG torch.
>
> Would the purge box help?
>
> Am I better off just finding a furnace brazing shop?
>
>