Sunday, May 24, 2009

Question about the flammability of aluminium‏?

Received the following question:

This is just idle curiosity... I was reading this article on the JHSV and just wondering what happens to one of these aluminum vessels in a war zone when someone drops some white phosphorus on it? Would it burn? Just wondering."

This question reminded me of the following Op-Ed piece by Retired Admiral James Lyons, former CINCPAC, where he wrote, "We continue to ignore the lessons drawn from the Falklands War where British ships with aluminum superstructures burned to the gunwales in a littoral sea fight with Argentine aircraft-delivered iron bombs and French short-range Exocet missiles."

So I decided to go looking for a little more information on this.

First, aluminium's melting point:

Melting point 933.47 K
(660.32 °C, 1220.58 °F)

Second, in looking up white phosphorus or WP, found this quote, "With a burn temperature of over 2200 degrees centigrade, the white phosphorus obliterates..." Also found this picture.

Third, here are a couple of related paragraphs out of Google books on this subject, one and two. But, the best clarification I found on the subject is here, definitely worth reading.

Fourth, as it pertains to these vessels, here is an interesting discussion with timely pictures onboard one of these aluminium vessels in question.

Lastly, here are a couple of related videos, one and two.

So an answer to the question is this:

I would say white phosphorus could burn some of the aluminium on the surface, but more importantly enough of it dropped overhead or otherwise activated within the structure (for example in the manner that was done in the Falklands War) at a minimum would cause aluminium structures to lose strength, become distorted, and fail.

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