JFS61 wrote:
Actually, it's not the formation of crystals from the salt water that causes the corrosion, it's the chlorides from the salt water. When exposed to the atmosphere, they combine with hydrogen to form hydrochloric acid (HCL) which in turn dissolves the metal from the inside out. More noble metals such as gold are immune to this, but as many people have found out the hard way, a less noble metal such as aluminum isn't.
After reviewing the links I posted I indeed noted that you are correct that it's the chlorides, not the salt itself. I am also glad someone was able to confirm that aluminum is susceptible to the same problems as iron. However, I am still a bit confused, but less so than when I began writing this post. The problem is the websites in the links confirm the understanding I posted about the crystals expanding and pushing the metal apart. The short version is I think we are both more or less correct. The long version is that I think
two different processes are being discussed here and we (or maybe just I) have been assuming there is only
one. The process of
deterioration I was describing
does not technically involve
corrosion. The process you are describing
does technically involve
corrosion. Both processes, however, involve
deterioration of the metal. The confusion arises because both processes involve some form of
chemical reaction and both involve salt in some way. However, in the process I described the
chemical reaction only
facilitates the
deterioration, that is to say the actual
deterioration of the metal is entirely through physical forces, or put more simply, pushed apart. In the process you described the
chemical reaction actually causes the
deterioration itself, with the metal being dissolved by the acid.
Please feel free to rebut my conclusion, it is based on my analysis alone and not supported by anything other than my observations, understanding and logic regarding the situation. (Actually, I'm no longer so sure that the process I described involves a
chemical reaction, but I'm too lazy, busy and tired to rewrite the paragraph.)
I hope that wasn't
too confuzzling.

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