[thermitequestion (OP)]

I want to make some aluminum powder to use in thermite, the premade stuff is too expensive for my country. I was wondering if i can make aluminum powder by grinding aluminum beams from windows/doors or aluminum cans using angle grinder (disc cutter). Will grinding produce the aluminum powder or the friction and the heat will  oxydise it  into aluminum oxide. I heard that if you mix the aluminum powder with a little charcoal it will keep it from oxydising?

[alancalverd]

Problem with grinding aluminum is that it clogs the grinding disc and either prevents it working or falls off in large lumps! You  could use a coarse rasp or Surform blade, but good thermite requires a very fine powder, usually made by spraying molten aluminum into an inert atmosphere.

Since Al will rip the oxygen from Fe2O3, I very much doubt that adding a bit of carbon dust will stop it oxidising.

[chiralSPO]

Aluminum powder is not particularly expensive, unless you want the really small particle sizes needed for making pyrotechnics or explosives. A quick web search shows I could get 250 grams for $15, plus shipping... I can't imagine it would be that different where you are.

250 grams is more than enough to get into trouble with. But be VERY careful, thermite is serious stuff!!! It gets so hot that it produces molten iron as it goes, and can inflict an incredible amount of damage to property and/or body in a very short amount of time. Improperly prepared thermite mixtures can also explode, showering molten and burning metal everywhere. I would recommend having a class D fire extinguisher on hand (and doing a lot more research) before playing with this stuff.

[Bored chemist]

I would recommend having a class D fire extinguisher on hand

I wouldn't.
It might lull you into a false sense of security.
You might, for example, think it will extinguish a thermite fire; (spoiler alert- it won't)

The appropriate fire control strategy for use of thermite is " do not allow anything combustible anywhere near a thermite reaction unless you are prepared to sacrifice it."
People, in this context, are combustible.

[chiralSPO]

I would recommend having a class D fire extinguisher on hand

I wouldn't.
It might lull you into a false sense of security.
You might, for example, think it will extinguish a thermite fire; (spoiler alert- it won't)

The appropriate fire control strategy for use of thermite is " do not allow anything combustible anywhere near a thermite reaction unless you are prepared to sacrifice it."
People, in this context, are combustible.

Fair enough. And yes, nothing can reliably extinguish thermite once started.

Essentially anything other than sand, glass, and concrete can be considered flammable under these situations. However, I would still recommend having the class D extinguisher on hand any time one is handling powdered aluminum.

[Bored chemist]

Essentially anything other than sand, glass, and concrete can be considered flammable under these situations.

and even they react...
https://ceramics.onlinelibrary.wiley.com/doi/abs/10.1111/j.1151-2916.1967.tb15049.x

Alumina is immune to the attack, but, unless you have plenty of it, it will melt.

[chiralSPO]

indeed. Thanks Bored!