Non-Chemical Test alloy for high temp casting

[Yggdrasil]

Thanks Lou.
I am dedicated to Rh on good and bad terms :wink:

Would not annealing after casting alleviate the
brittleness?
It is considered malleable in most litterature, which indicate that it can be "beaten" into shape at least once,
at least that is how I understand the term.

 

[Yggdrasil]

After reading around I have found it neccessary to
revise my plan.

It seems vacuum melting could lead to losses
of tenths of grams depending of time, surface
and vacuum.

It seems that the most sound approach will be to
melt under a mild pressure with argon or similar and
then pour/evacuate to a secondary chamber
with vacuum.

I have seen this design in casting furnaces so it
should dooable.

It is strange how things evolve.
I started with some ideas about how to do things.
And had become quite confident over time that it
would be that simple, then I asked a few not well
founded questions.

Then people ask back and hints to well known facts and laws of nature and it all change.

Thanks folks, this is what makes this forum so great
:mrgreen: :lol:

 

[stella polaris]

After reading around I have found it neccessary to
revise my plan.

No plan survives reality... A known fact..

 

[Yggdrasil]

That is where plan B +++ and contingencies come into
effect. This time though, the evaporation/sublimation
issues had completely bypassed my mind
Due to the forum I'm on track again

 

[Lou]

Thanks Lou.
I am dedicated to Rh on good and bad terms :wink:

Would not annealing after casting alleviate the
brittleness?
It is considered malleable in most litterature, which indicate that it can be "beaten" into shape at least once,
at least that is how I understand the term.

You can try and anneal it and it will probably help. Malleable though? Ehhh...I'd say more ductile than malleable and there's a lot of tricks into making it into wire (by the way, the wire itself is almost fibrous in structure). I can smash a button of Rh with a hammer into smithereens. It's not as bad as Ru or Os in the brittleness department but it isn't great.

Why don't you just cast an 80 % Pt 20 % Rh alloy? Very white, much cheaper, great alloy, nice and hard...

 

[kurtak]

Interesting thread - out of my knowledge base (so can't really contribute) but interesting none the less --- thanks for posting :G

Kurt

 

[Yggdrasil]

Thanks Lou.
I was contemplating to solder the prongs on to the ring and use 30/70 Pt/Rh alloy.

And you are right they use some tricks to pull Rhodium thread, I have found that one way was to embed a
Rhodium rod 3mm into a Nickel tube and then pull it
before the Nickel is dissolved in HCl.

They would not go to these lenghts if it was easy,
but then pulling a thread means repeated stress in the same area over time. Tapping a localized piece a few times into a defined position/form is a completely other ballgame, I guess.......

Interesting to see the Rhodium ring still inside the investment, nice luster and color too

Kurt.
This forum is rewarding in many ways, and it is nice to see that other people enjoys the threads too
I for one has found ideas and educational information all over the forum.
Your posts are always informative, among the posts of
many other esteemed members.
So I thank you all for that

 

[stella polaris]

Its off topic but it seems interesting.
Should it not be possible to use vaccum and heat, to purify pm from metals with low boiling temp? (or vice verse) If pm losses could be hold low it would be a quite clean way of refining.

 

[Lou]

Sure.

A lot of refining comes from the process of evaporation during say, floating zone electron beam remelting (a refining procedure).

On metals with appreciable vapor pressures, like iridium, losses can get...expensive!

I have personally fire refined Pt alloys many times. You can slag off a lot of crap with melting the Pt and running oxygen through it.