Argentina sunk a biritish bioat

[N35t0r]

I think it is actually aluminum and ammonium perchlorate (so yes?) but not positive that is what is used on an exocet.

That sound more like solid rocket fuel than thermite.

[PLATO]

That sound more like solid rocket fuel than thermite.

Yes, but they are pretty close in composition. pchang says it would need iron as well to be thermite. I am certainly not an expert but am just a layman.

[N35t0r]

Thermite is usually powdered iron oxide and powdered aluminium.

Other metal oxide/ metal combinations also work, but that one is the most common.

Ammonium perchlorate is a very strong oxidizer agent used for a lot of solid rocket motors (the space shuttle and SLS for example)

[Dauphin]

Yes, but they are pretty close in composition. pchang says it would need iron as well to be thermite. I am certainly not an expert but am just a layman.

I was assuming there would have been some rusted iron somewhere, and it's not a pure aluminium vessel.

[N35t0r]

The reaction isn't as violent if the reagents aren't powdered and mixed together

[pchang]

Also, if it is rusted, it will not burn. If it is not powdered, It needs to get hot enough to essentially liquify the metal so fresh un-oxidised material is exposed to oxygen.

[Dauphin]

I don't understand what you mean that if it is not rusted it will not burn. Thermite can be made from iron oxide and aluminium so not understanding your point. Possibly due to the odd punctuation. Are you meaning it won't be self-sustaining if not powdered / does not have the necessary surface area exposure?

I'm getting flashbacks to science lessons when custard powder and flour explode when it is aerosolised, and doing newton cradle experiments with large rusted iron and aluminum balls.

[pchang]

I sad that rusted iron will not burn. It is already oxidised. Thermite is made from powdered aluminum and iron. Oxidation = burning as far as the end products go. Iron oxide = rust = iron that has been burned.

[Dauphin]

Thermite is mixture of metal and metal oxide. Yes, burnt means the end product, but the distinction seems a bit strange in the context of a redox reaction.

[N35t0r]

Yeah, the rusted iron is the oxidizer (or whatever other metal oxide is used); this means that the reaction can happen without outside air, and makes it incredibly difficult to stop once ongoing.

The elemental metal has to form an oxide with more energetic bonds than the metal oxide. Once enough heat is applied to overcome the activation energy, the reaction starts and the released heat from the redox reaction makes it sustain.

[N35t0r]

The standard iron oxide / aluminium thermite reaction is for example used to weld rails together, since the iron melts and forms part of the resulting weld (I guess with a properly formulated flux to ensure that the resultant weld metal is some kind of steel with acceptable mechanical properties)

[Edit:] also copper/aluminum thermite mixes are used to weld high thickness wires to steel pipe for cathodic protection purposes.

[Bereta_Eder]

As long as the initial point remains clear I don't mind the scientific turn this thread took

[pchang]

I remembered the thermite reaction incorrectly. But, according to Wiki, Sheffield did not have an aluminum superstructure. The missile took out the main water system for firefighting and that is why everything burned. Then, being towed in rough water, enough water got in the hole in the side of the ship to roll it over and sink it.