Material for holding aluminum melt
Material for holding aluminum melt
(OP)
What would be the best material for holding a small amount (one cu. ft) of liquid aluminum at its melting point (1220 F or 660 C) at atm. pressure?
Do I need to use costly ceramics (Silicon carbide, graphite) or does Stainless Steel (304?) can do the job?
Do I need to use costly ceramics (Silicon carbide, graphite) or does Stainless Steel (304?) can do the job?





RE: Material for holding aluminum melt
The C/S crucibles are relatively cheap. It all depends on the how much you are going to use it.
RE: Material for holding aluminum melt
And, is this high purity aluminum that you need to avoid contaminating?
I suggest using a ceramic coating more thermodynamically stable than Al2O3 or else Al2O3 itself.
For short-term use preparing experimental alloys, I have used spray + bake coatings of stabilized-zirconia, yttria and BN from Zyp on crucibles, and paint-on graphite coating on cast iron chill molds. http://www.zypcoatings.com/
(BN is also available through www.mcmaster-carr.com p/n 10515K35 )
For long term use, suggest Al2O3 crucible inside ceramic-lined carbon steel (always a chance of crucible breaking!). Zirconia-based refractory inside a steel shell also works. If you are pouring in liquid Al from a furnace, pre-heat the crucible with a natural gas flame.
Also, if there is an aluminum foundry nearby, pay them a visit.
RE: Material for holding aluminum melt
There are quite a few caveats in dealing aluminum casting.
Molten Aluminum doesn’t like moisture in any shape or form. The moisture can come from any things like the sugar in Aluminum cans that had been baked to dry out. The temperature wasn’t high enough and the person lost the aluminum he was melting. Molds can be big problem usless done right. Preheat every thing that goes into the pot.
If you are going into an industrial area I would suggest a very formal process audit and the purchase of some reference books prior to commencing any casting.
If it is one-up type work try the following website.
http://www.lindsaybks.com/
RE: Material for holding aluminum melt
The idea is not to cast parts or recycle scrap alum. but to use the phase change of a given amount of clean (and chemically "flat") alum. in a "thermal battery". So the same alum. is to be remelted over and over. Nasa used graphite crucible for the same purpose but without any mention of coating to stop graphite burning. Ref: S.M. Raqué et al. AIAA doc A97-31343 page 5.
In my case, alum would also be confined in a close vessel (crucible). No contact with O2, N2 or H2O. Do you think that a good coating (ex. Ceramic Oxyde, trade name Sealmet or Silicone Carbine, trade name Covergard both from Zyp) over graphite will last?
Your answers are always appreciated.
Best regards
Denis
RE: Material for holding aluminum melt
I would contact ZYP coatings with your specific problems. The people there are very knowledgeable and quite helpful. I been looking for some names, but can't lay my hands on any.
If not mistaken their original coatings were for Graphite.
RE: Material for holding aluminum melt
RE: Material for holding aluminum melt
Eulogio Velasco
Melting Process Eng
Nemak