Thermite Casting

[Jared Stenoien]

I was wondering if anyone here has tried casting with thermite and if so what tips you may have. One thing I would really like to know is if properly preheated plaster of paris would be fine to use for the mold. Thanks in advance.

 

[sunshadow]

whyand what do you want to cast with thermite?
Plaster of paris is not a high temperature material, Thermite is. Plaster will be difficult to completely rid of trapped water and the last thing you want under molten thermite is a steam explosion
Platinum casting investment may be capable of working with thermite, but you really need to know what you are doing

-Page

 

[mete]

What do you want to do with it ? It has limited use for example ,welding RR tracks together.There is also copper thermite .There is a member of Swordforum who makes steel with it in a crucible .He invents his own alloys.

 

[rhrocker]

whyand what do you want to cast with thermite?
Platinum casting investment may be capable of working with thermite, but you really need to know what you are doing

WHOA! Platinum casting investment? Now that's a new one on me!

 

[Jared Stenoien]

I wanted to try some small iron castings, I've done lost wax casting with aluminum and plaster before but thermite I realize is quite a bit hotter. Could I buy platinum casting investment from Rio Grande? Mete do you have an email for that person?

 

[Colin KC]

...but thermite I realize is quite a bit hotter.

Hi Jared, yeah, around 5,000 degrees hotter. you'll have too many problems controlling a thermite run to achully make a moulding, sorry but it's not really viable.

 

[B Finnigan]

If you use a primary combustion crucible and use a mold for the catchment you could cast some simple shapes but you will also get alot of slag in the mold. On all the charges I have done up to 50% of the secondary catchment is slag. The slag seperates and solidifies on the top of the button.

You can see the liquid iron running out of the primary combustion crubible after the the steel tap has melted.

 

[mete]

Finnigan, That's the way !!! I notice that you don't have any neighbors !!
Jared , his name is Jerry Bennett and you can find his posts in the metallurgy section of www.swordforum.com. I think you really want investment casting for small parts.

 

[sunshadow]

I wanted to try some small iron castings, I've done lost wax casting with aluminum and plaster before but thermite I realize is quite a bit hotter. Could I buy platinum casting investment from Rio Grande? Mete do you have an email for that person?

Rio Grande sells Kerr Opticast as a high temp platinum compatible investment ( item 702-347) and R&R platinum which states it is "also suitable for some ferrous metals" (item 702-337) That said, if you are looking to cast iron, Thermite is not the way to go, there are forums for people who do backyard foundry work, I suggest you find them and do a LOT of reading! Casting has an expensive learning curve, and the higher your metal temps are the more dangerous your learning curve becomes. Start with white metal, (pewter) then bronze (don't do brass, the zinc fumes WILL kill you) and once you are getting consistant results with bronze start considering casting iron.

Read a lot. If you don't burn out your investment right you can get steam bubbles which can cause molten metal to volcano everywhere.
hate to be a party pooper, but then again the last thing I want to see is forum damage photos of burnt flesh from anything other than one's first forge weld (which invariably seems to involve at least one belly splatter flux burn followed by grinning like a fool)

-Page

 

[B Finnigan]

I use a SiC catchment crucible that is pre-heated to reduce the shock of it going from ambient air temp to 3000 deg. Pre-heating also allows for a slower cooling which will purify the iron/steel a little better. It's also imbedded in vermiculate to insluate it and thus slow the cooling down even more.

Thermite is fun and interesting to play with but there is no consistancy in the end product. You could get a near pure iron button or something close to cast iron. And that is while using the same mix ratio.

There are several little tips/tricks to using it for steel/iron production.