| Author | Message | ||
     lysdexia Unregistered guest |
On his site I was led to the webpage showing that mercury (but mercury chloride) paste put on an aluminium girder corroded it rapidly, which is why airlines don't allow any mercury brought on board. Theodore claimed that the mercury penetrated the oxide coating, allowing more oxygen through, but didn't offer an explanation. Mercury doesn't even form an oxide well. How would it bring oxygen in? Could it be the chlorine that broke apart the oxide layer? | ||
| Simon Quellen Field (sfield) New member Username: sfield Post Number: 94 Registered: 12-2004 |
The same thing happens with gallium and aluminum. An amalgam of the two metals is formed. The aluminum oxide cannot form a protective layer, since the crytal structures no longer match as they do with plain aluminum. This is why iron rusts and aluminum is protected. The iron oxide has a larger crystal structure than the iron, so it flakes off, exposing more iron to the damp air. Aluminum is much more easily oxidized than iron, so it reacts quickly with water, forming hydrogen bubbles and aluminum hydroxide. The aluminum atoms at the surface of the amalgam are no longer protected by a shield of aluminum oxide, because the oxide won't stay on the amalgam. As the atoms of aluminum are removed from the surface of the amalgam, new ones migrate up into it, and are consumed. It isn't oxygen getting in -- it is aluminum coming out. | ||
| lysdexia Unregistered guest |
Is AlHg a liquid? The hydroxide I read is a weird (my word) gel. How much do you know about chemistry? I bought a dilating caliper set with interchangeable parts on eBay. It'd been tarnished all over so I guess it was relatively cheap. When it got here it was extremely smelly—why? I've never heard of steel smelling, only osmium. I didn't really know how to clean it, so I tried tile cleaner which got off the smudges, but parts got tinged yellow in hours. What is this made of and how should I clean it? Should I try passivating it with nitric acid? peroxide? bleach? |
