Sciencemadness Discussion Board

Cleaning crucibles

macropause - 6-8-2013 at 08:56

Hello everybody,

I have a problem with cleaning crucibles. I've melted LiFeVPO4 in alundum crucible and I have no idea how could I remove the solified substance from it. Have anyone of you ever coped with it?

Thanks in advance for any help.

blogfast25 - 6-8-2013 at 09:08

Quote: Originally posted by macropause  
Hello everybody,

I have a problem with cleaning crucibles. I've melted LiFeVPO4 in alundum crucible and I have no idea how could I remove the solified substance from it. Have anyone of you ever coped with it?

Thanks in advance for any help.


Melt it again and cast it onto cold marble slab? What's LiFeVPO4 good for?

bfesser - 6-8-2013 at 09:13

<strong>blogfast25</strong>; batteries.

<strong><a href="http://www.physics.rutgers.edu/~croft/papers/180-LiFeVPO4-jp2034906.pdf" target="_blank">Effect of Vanadium Incorporation on Electrochemical Performance of LiFePO<sub>4</sub> for Lithium-Ion Batteries</a></strong> <img src="../scipics/_pdf.png" />
<strong><a href="http://search.proquest.com//docview/305106875" target="_blank">Synthesis and characterization of high performance electrode materials for lithium ion batteries</a></strong> <img src="../scipics/_ext.png" />

Sorry, I have no advice for cleaning your expensive crucible, <strong>macropause</strong>. I've been scanning the lit. since you posted, but haven't found anything yet. I'd imagine that the vanadium will make little difference, so if you find anything in the experimental section of a paper on LiFePO<sub>4</sub>, it may be of use. I see a mention of a carbon-coated alumina crucible used for this, perhaps to protect the crucible from the melt (<a href="http://link.springer.com/article/10.1134/S1023193512110055" target="_blank">source</a> <img src="../scipics/_ext.png" />;). <a href="viewthread.php?tid=11021">This thread</a> may give you some ideas on what you could try without dissolving your crucible.

[Edited on 6.8.13 by bfesser]

watson.fawkes - 6-8-2013 at 09:47

Quote: Originally posted by macropause  
I've melted LiFeVPO4 in alundum crucible and I have no idea how could I remove the solified substance from it.
As blogfast25 said, melt it again. Crucibles are refractory for holding materials at heat. They are not casting molds for allowing the melt to solidify (as you've discovered). You can make an ad-hoc ingot mold by pressing a form into a pan of sand.

macropause - 6-8-2013 at 13:34

Melting it again is, unfortunately, bad idea, because it will solidify on the lateral surface of crucible before flowing out of it - and I want the crucible to be perfectly clean.

I guess I try to dissolve LiFeVPO4 with Aqua Regia or other acids - as someone discovered in one of topics sent by bfesser, Al2O3 doesn't dissolve very quickly.

Thank you all for your answers and ideas:)

watson.fawkes - 6-8-2013 at 14:59

Quote: Originally posted by macropause  
because it will solidify on the lateral surface of crucible before flowing out of it
And just how is that? The charge is above its own melting point. The crucible is above that melting point. Presumably the crucible has enough heat capacity not to cool below the melting point before you can pour everything out. The only thing remaining is any droplets stuck on by surface tension, but that's the best case scenario. You may need some acid cleaning afterwards if you want "perfectly clean", but it's a lot easier to do that for only a few milligrams of material than a whole crucible charge.