guy
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Which material is suitable for working with hot H3PO4?
It attacks glass and most metals. Does it attack aluminum or copper?
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Baphomet
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What about a crucible made of a refractory material like Al2O3?
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Organikum
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Teflon. Several kinds of SS steel - the steel once passivied is mostly resistant against the acid.
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unionised
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Copper should be OK in the strict absense of oxygen. Aluminium might be a bit violent.
Al2O3 certainly should react, but it might be slow enough not to matter.
Aluminium phosphate is used as a ceramic but I think it might not stand up to the free acid.
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Baphomet
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I like the Aluminium Phosphate idea. Just guessing but would the phosphate ions suppress the donation of protons from the acid due to being the same
as the acid's anion?
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unionised
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Actually, I suspect that you would get a whole mess of Al salts with
PO4---
HPO4--
H2PO4-
and lots of other things all of which would reduce the melting point of the AlPO4 untill it all turned into a liqid mess.
OTOH, I have't tried it; just don't try it with anything expensive first.
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BromicAcid
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To some extent this question was tackled in the thread on making polyphosphoric acids as dehydrating agents:
http://www.sciencemadness.org/talk/viewthread.php?tid=4409
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Eclectic
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Well, after reading through the post linked to above, It doesn't look like anyone has actually tested an alumina crucible to see if a surface layer of
AlPO3 forms and protects the rest of the crucible.
Chloric1's breakage was likely due to thermal stress.
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