Induction melting buttons and small ingots of platinum

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aurelius

Member
Joined
Mar 3, 2021
Messages
9
Hi all, I've been reading through a bunch of previous posts, and am curious about a couple things. I am going to be trying to melt some Pt scrap pieces (not powder), within the coil of an induction heater, into buttons and ingots, letting them cool in the crucibles. From what I've seen so far, the following seem to be true:

1. Don't use alumina due to temps; use YtSZr or MgO
2. Ideally, I should bed an inner crucible in sand within an outer crucible for shock purposes

Based on the weights I'm striving for (< 50g) I've also seemed to gather that #2 may not be strictly necessary? If I used a small, solo rectangular YtSZr/MgO crucible directly in the coil, would that work?

My initial planning has me placing the melting crucible in the coil, turning it on, letting it melt, then turning it off and letting the metal cool, but I'm sure I'm probably missing more to this :)
 
You might consider just buying a hydraulic press and pressing your own crucibles out of MgO or CaO then hard firing them. You can even build a little lime block furnace and use that as an oxidizing atmosphere is best for Pt (less sticking than neutral with induction, but induction less noisy and more convenient).

50 g boats out of stabilized zirconia are expensive. In fact, at work we only use the zirconia crucibles if we are dealing with high purity metal that we are going to try pouring. Then the platinum is essentially nonstick.

For just melting and getting a weight, you can use silica or alundum if you use good ventilation.
 
Lou said:
You might consider just buying a hydraulic press and pressing your own crucibles out of MgO or CaO then hard firing them. You can even build a little lime block furnace and use that as an oxidizing atmosphere is best for Pt (less sticking than neutral with induction, but induction less noisy and more convenient).

50 g boats out of stabilized zirconia are expensive. In fact, at work we only use the zirconia crucibles if we are dealing with high purity metal that we are going to try pouring. Then the platinum is essentially nonstick.

For just melting and getting a weight, you can use silica or alundum if you use good ventilation.

My hope is to end up with buttons and ingots that aren't the "prettiest" but more similar to a poured appearance. I've gotten most of it just need to work on not overheating the crucible ;)

Thanks for all your previous posts, btw, I relied on a good smattering of them to really narrow down to where I'm at now. I'm sure you've heard it many times before, but you're a great resource to have here!
 
Happy to help!

Working with clean platinum is a fabricator’s dream. What great stuff to mess around with!!
 
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