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document updated a month ago, on Apr 12, 2024

thermite as a heating method

pros and cons

Pro — powdered aluminum + iron oxide can reach a temperature of 2862°C / 5183°F. Having that much heat available in a relatively safe-to-store format is really nice.

Pro — "Shelf life is indefinite if stored properly". It really can not ignite until all three pieces are combined (Al + Fe2O3 + Mg), so storing them separately should keep things safe. Magnesium is pretty difficult to accidentally ignite. The more finely-powdered the aluminum is, the more of a fire hazard it is by itself.

Con — It tends to spit molten blobs in the surrounding area. It's important to maintain a safe distance.

Con — While it is sometimes used for welding, it's a pretty uncontrollable reaction, in terms of hitting a specific temperature, holding the temp there, and then using it to accomplish some task.

Con — As far as I know, it's difficult to have a very small reaction, it seems like these are usually minimum 50 mL. (but that's just based on observation of patterns; I don't know if that's a hard minimum, or if it can be worked around)

specific formulations

The most common mixture used is:

It should be mixed in the ratio of one part aluminium to three parts iron(III) oxide, by weight.

practical details

Tips [1] [2] [3] [4]

Advice for grinding aluminum in a ball mill.

Possible ways to slow the reaction down: Use larger particle sizes. Adding iron or steel will make it burn less hot, as energy gets used up in melting this metal.