Re: How good would Aluminum armor be?
 

I don't think so. Aluminum is the fuel in thermite and iron oxide si the oxidizer. I think that says "aluminum burns better than steel" pretty clearly.

Re: How good would Aluminum armor be?
 

Aluminium is only useful as thermite because the particle size is very small. It doesn't react the same if it is armour plate.

http://www.g2mil.com/aluminum.htm

"Aluminum and Iron will burn as will any other metal, if it has a sufficiently sized particle. For both metals it is a very small size. A single plate will simply react on the outer layers however the outer skin will be covered in ash from the combustion and protect the inner plate."

Apparently, all of the so-called examples of burning aluminium armour have turned out to be the contents of the vehicle burning, not the metal itself.

Re: How good would Aluminum armor be?
 

Or.....

"Aluminum is more reactive than Steel,"

Sometimes you can overthink these things.

Re: How good would Aluminum armor be?
 

It is only reactive until the surface forms a protective barrier of oxide.

Re: How good would Aluminum armor be?
 

Yeah a big differnace, Aluminum Oxide creates a protective barrier, Iron Oxide as a corrosive effect.

Re: How good would Aluminum armor be?
 

On the modern battlefield and on any higher-tech version, aluminum armor is a BAD IDEA.

Low-tech aluminum personal armor is an oxymoron. It isn't available at all until late TL5 and then it's very expensive. The Washington Monument has a cap made of aluminum, which was more expensive than silver in 1884.

Of course, if you want to build a civilization of intelligent cockroaches after the big-oops, all those non-biodegradable aluminum cans provide a practically-endless source of metal. And maybe some smuggler is making a fortune "recycling" old cans to Microworld.

Re: How good would Aluminum armor be?
 

No, the total combustion of some aluminum structures is well-documented and not just the military examples quoted in the article you seem to be ignoring. It's also seen quite commonly in civilian aircraft disasters.

Try this one for a simple example.

http://aviation-safety.net/wikibase/wiki.php?id=22676

The skin isn't just melted, it's burned to ashes. That doesn't happen to the steel body panels of automobiles in simialr situations. The surface layer of aluminum oxide didn't protect it. All aluminum in an oxygen atmosphere already has such a surface layer anyway. Aluminium is _that_ reactive.

Re: How good would Aluminum armor be?
 

The question is whether the aluminum would burn in a fire that isn't already hot enough to completely destroy the structure. It doesn't specifically matter if the aluminum is destroyed in a fire (if it would have been melted anyway, it's not much worse to have it be ash), it matters whether the aluminum is making the fire worse. In your example, it's a fuel fire that consumed the aluminum, not an aluminum fire.

Re: How good would Aluminum armor be?
 

But the aluminum didn't just melt. It did burn. That releases heat pretty much by definition. I have trouble seeing how more fuel and hotter fire doesn't equal more destruction.

Re: How good would Aluminum armor be?
 

Something cannot be more than completely destroyed...