Thermite, good for casting iron? 1

[balishma]

Ok, first off heres my task,
Casting an iron anvil
To get a lot of Iron Oxide and Aluminum shavings, make a mold out of cement, use a magnesium ribbon to ignite the thermite, funnel it through rock into the mold, and leave to harden.....

couple of questions....
is this suicidal? (it would recuire lots of thermite, lots)
and to make an anvil, (like a couple of gallons of iron maybe more, havn't tested yet, just in the questioning stages) how much thermite is recuired, useing iron oxide (rust) about how much iron would you get out of it?

thanks for all of your help!

 

[nbucska]

Rust is hydroxid!!!

<nbucska@pcperipherals.com>

 

[balishma]

Rust is a commonly seen form of iron oxide.... its just a form...

now back to the question, will that much thermite.... well, explode, or how should i administer them to the mold..... like a small amount at a time....

 

[moltenmetal]

Thermite yields white-hot iron (and LOTS of sparks) and will melt pretty much any refractory you choose to use with it. So the mold and "funnel" will be pretty rough to come up with. "Cement" isn't going to cut it.

This is crazy. Why don't you just buy an anvil? The Chinese iron castings are so cheap these days I can't imagine why anyone would bother.

If you're serious about doing some hobbyist iron casting there are plenty of websites out there which will tell you how to make a back-yard foundry- one that will run a much lower risk of getting you dead, and a much higher chance of producing a useful casting. I've made such a foundry myself (hence the nickname on this forum) and use it to do bronze sand-castings. My refractories are a little cheaper so I can't cast iron, but the technology to do so isn't all that hard to come by.

 

[kenvlach]

STOP!!!
A very dangerous steam explosion will result if you use rust; as nbucska warned, it is a hydroxide or to get technical, a hydrated oxide. Its formula may be written FeOOH or xFe[sub]2[/sub]O[sub]3[/sub][sup].[/sup]yH[sub]2[/sub]O or Fe[sub]2[/sub]O[sub]3[/sub][sup].[/sup]2Fe(OH)[sub]3[/sub], none of which is tolerable for exposure to hot aluminum.
You may be able to heat rust in an oven to convert it entirely to Fe[sub]2[/sub]O[sub]3[/sub]. You must also bake your mold. Back when I was melting aluminum in an induction ladle, we would preheat it with a natural gas lance for up to ½ hour before charging with Al.

As to quantity, the density of Fe is 7.87 g/cm[sup]3[/sup], so from the volume of the anvil, calculate the amount of Fe and hence initial Fe[sub]2[/sub]O[sub]3[/sub]. Since atomic weights are Al 26.98 and Fe 55.847, you will need 48.31 % by weight of Al and 143% Fe[sub]2[/sub]O[sub]3[/sub] per unit weight of Fe produced according to the formula

Fe[sub]2[/sub]O[sub]3[/sub] + 2 Al = Al[sub]2[/sub]O[sub]3[/sub] + 2 Fe

It would probably be wise to allow 25% extra.
Unless you have a free source of Al powder or shavings, the cost of the Al will be greater than the price of an offshore anvil.

Unclesyd gave some good links for the Thermit welding process in thread725-88650

Please let us know if you are still alive and if still proceeding.

 

[Dissymmetry]

Fe2O3 is Iron Oxide III or Hematite. You ould be best off ordering reagent grade Iron III Oxide from a reputable chemical supply. Also, Aluminum shavings will not be fie enough to continue the reaction, you will need fine powder of each of these materials to cause a thermite reaction. That's to get a solid thermite reaction going anyhow, as to using thermite to create an anvil I think the material would be too porous to be of any real use supposing that you were able to do it somehow.

 

[nbucska]

more than 50 yrs ago I have seen a picture of using thermite to weld railroad tracks. They poured the molten iron from a long-leaded container into a form -- smoke and
sparks everywhere...

<nbucska@pcperipherals DOT com> subj: eng-tips

 

[indy1687]

hey,
i have tryed thermit before and i got book a called
Thermit Welding Process by Richard N. Hart
it is a good enough book detailing along the lines of what you want to know. It is an old book(originally published in 1910). you can get the book from

http://www.lindsaybks.com,

bewarned thermit is dangerous and the melting al and fe2o3 can erupt and spray sparks everywhere.