RE: Aluminum "eating" ...
Hi all,
While this is not entirely relevant, did you know that there is something that appears to "eat" aluminum?
If you place a small droplet of mercury metal (a liquid at room temperature) on a piece of aluminum metal, then over time the aluminum metal will disintegrate into a pile of rubble! Actually, what happens is the mercury "cleans" the aluminum making a fresh aluminum surface. The aluminum then oxidizes in the air. The mercury acts as a catalyst, it is not consumed in the process, so the entire block of aluminum will eventually oxidize into a pile of aluminum oxide (Al_2O_3) dust.
Normally, a block of aluminum metal does not have actual aluminum metal in contact with the air, rather it is covered by a thin coating of aluminum oxide that protects the bulk of the aluminum metal from oxidizing further. This thin aluminum oxide, also known as corundum, is quite hard and is insoluble in water, and therefore it provides a significant protection to the aluminum metal from scratches and water. The natural process of forming aluminum oxide on the surface of a piece of aluminum can be enhanced by a process known as anodizing. Anodizing not only increases the thickness of the aluminum oxide coating making it harder and more scratch resistant, but it can also color the aluminum oxide with other ions to produce various other colors of anodized aluminum.
When you scratch a piece of aluminum metal, you cut through the aluminum oxide protective coating exposing aluminum metal to the air, but the aluminum metal immediately oxidizes forming a new aluminum oxide layer protecting it from further oxidation. This is why we say that iron rusts, but aluminum does not. As a point of fact, aluminum actually "rusts" (oxidizes) faster than iron, but aluminum oxide is quite hard and sticks to aluminum metal and itself and thus forms a protective layer on the aluminum block. An iron block, on the other hand, "rusts" (oxidizes) but the ferric oxide (rust) is not very hard and crumbles easily, thus the iron rust flakes off the iron block exposing fresh iron metal to the air and thus to further oxidation. Hence, over time, a block of iron will oxidize completely forming a pile of ferric oxide (rust) dust. But an aluminum block will not oxidize completely since its initial aluminum oxide protects the remainder of the bulk aluminum metal from further oxidation. (Unless, of course, there is some mercury metal around that "cleans" the aluminum block allowing it to oxidize fully into a pile of aluminum oxide dust.)
...just thought this was an interesting chemical reaction, as it is quite surprising to watch a large block of aluminum being "eaten" by a small drop of mercury.
Regards,
Switon
P.S. So, I have to ask the OP, did you get any mercury on your MBP's case? If so, then the entire case will eventually disintegrate into a pile of aluminum oxide dust. Acids slowly dissolve the protective aluminum oxide coating on aluminum, and thus acids will "pit" an aluminum surface --- this is probably what is happening to your MBP.
