I’ve been reading the info on fusing platinum with great interest,
even though I don’t work with Pt.
It does make me wonder, though: is it possible to fuse palladium?
I’m particularly interested in Hoover and Strong’s Palladium 950,
which is 95.2% palladium plus “others”. I plan on asking them next
time I order, but would also appreciate any experiences fellow
Orchidians can share- with this or other palladium alloys and/or
solders.
As people were saying in the Pt thread about some Pt solders, I like
the metal but am not best pleased with the solder color match, and am
looking for a better alternative.
keep in mind the carbon and oxygen free requirements for palladium
ive had success at pouring ingots and rolling sheet but i aint
telling the secret until i am assured the credit will be mine - goo
Amanda, it is possible to fuse palladium. I have done experiments
with various methods. I have concluded that TIG welding in the half
second to several minute range, with variation of amperage input
during the weld cycle, to be the only satisfactory method. The spot
welding methods that deliver a single energy level of input, cause
cracking during re-solidification of the metal. This cracking is in
various degrees depending on the source of energy. Some of the
samples I tested only showed cracking under magnification, but
proved weak in stress tests. This type of defect can go unnoticed for
weeks before failure. TIG is the only method that consistently
provided durable welds free of stress cracks. Hoover and Strong’s 950
Tru-Pd is composed of Palladium, Gallium, Silver, and some traces of
other metals that are trade secrets. I have found that Tru-Pd will
develop a more fluid puddle than other Pd alloys. This is very useful
in assembling components. Tru-Pd is only slightly less durable than
other alloys in stress tests. All Pd alloys can be increased in
hardness by burnishing or hammering. I suggest that a casting should
be under sized and slightly over weight so that the shank can be
hammered up to correct size and work hardened. I have had great
success with palladium pieces. Some have been out in the world over
four years now and are wearing satisfactorily.
Fusing is another name for welding. You cannot weld 950 Pd with a
torch but you can TIG, Pulse Arc or Laser weld it.
Later generation lasers might do better than the two I use (a five
year old Rofin, and a ten year old BD/Alpha Sirolaser. Both can use
argon shielding, but neither has pulse shaping. On both, laser welds
on 950 palladium end up with spiderweb cracks and porosity. You can
fix minor surface pits on a casting, but a more substantial weld like
a sizing seam in a ring doesn’t turn out acceptably.
The spot welding methods that deliver a single energy level of
input, cause cracking during re-solidification of the metal. This
cracking is in various degrees depending on the source of energy.
I called Kevin today and we talked about this some. I use my PUK II
to weld 950 Pd alloys from Stuller and DH Fell regularly and have not
had any cracking problems. I tack weld the Palladium/Sterling mokume
rings I make before trying to solder the butt joint of the band as if
it is not tacked it will twist due to the different thermal expansion
rates of the palladium and silver. We also tack many of the
fabricated palladium items before soldering. I went into the studio
today and did a couple of butt joints in 1 mm thick Pd 950 and did
not have any cracking visible at up to 100X magnification. So I am
somewhat baffled by his experiences. But it may have something to do
with alloy differences or possibly differences between the welder he
is using and the PUK II. It could possibly be that the palladium
needs to be preheated before welding. Short pulse type welds like the
pulse arc machines or the laser have super fast cooling rates due to
the short duration of the welding pulse. This can lead to high
stresses that can cause cracking. In other types of welding it is not
unusual and often required to preheat the work to 300-600 F before
welding to prevent cracking upon cooling. We talked about a couple
ways to do this. One I tried is to use a hot air gun to heat the
workpiece just before welding. It worked as far as I was able to pre
heat the test piece before welding but I was already getting a good
weld so I don’t know what was proved. The other idea was to use a
clean copper tipped soldering iron to preheat the spot before
welding. Or just a torch but it would be very easy to overheat the
item with a torch. Anyhow it is possible to do this type of weld with
a PUK II pulse arc welder. Of course if you have a nifty TIG unit
like Kevin’s then that is a good tool to use as well. My skills with
the TIG on jewelry are not quite as good as Kevin’s but it is a great
tool and I am trying to bring it more into use in my jewelry studio
work.
Later generation lasers might do better than the two I use (a five
year old Rofin, and a ten year old BD/Alpha Sirolaser. Both can
use argon shielding, but neither has pulse shaping. On both, laser
welds on 950 palladium end up with spiderweb cracks and porosity.
You can fix minor surface pits on a casting, but a more substantial
weld like a sizing seam in a ring doesn't turn out acceptably.
Peter if you can manage it try preheating the Pd950 before trying to
weld it and see if that makes a difference. 300-600 F. I don’t know
if you can rig it but I think it may make the difference.