As we all know to have fire you need fuel, oxygen and a spark. But what is needed for rust? Why does it keep growing? How do you stop it?

I haven't slept in weeks thinking about this http://www.chevelles.com/forum/rolleyes.gif

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ACES member #04788
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Have you ever noticed that those instruments designed to detect intelligent life in the universe are all pointed AWAY from Earth???
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i think its oxidizing iron or something along thise lines. idk i could be wrong...i never listen in chemestry http://www.chevelles.com/forum/biggrin.gif someone has to know the right answer.

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Steve
1972 el camino
hey its not done but check out its progress.
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rust is iron oxide and the fuel is water and oxygen. if you have steel exposed to oxygen and moisture you get iron oxide (rust)

For rust, you need iron-based metal, and water (vapor). It only keeps growing if allowed too...

Rust is iron oxide... it is just a natural corrosion process that occurs to unprotected iron... Since steel is made from iron, it is susceptible to rust... Aluminum also corrodes and creates aluminum oxide. other metals corrode too...

Its been a while since Chemistry, so I forget the specifics, but basically I think it is a chemical reaction between the oxygen molecules of water and the iron... To keep rust from forming, some sort of coating must keep the water (even vapor) away from the steel, such as paint or oil... Places like Arizona and California have less humidity and therefore generally less rust than other parts of the country. Parts of California near the ocean though, are subject to significant rust... Road salts and other de-icers also help promote iron oxide in forming.

Once rust is started, the process will continue, even when coated, which is why you have to cut out all rusty metal and replace before painting, or the rust will quickly show itseld by bubbling the paint, etc. Thats why its commonly called "cancer"

There are some products on the market that supposedly "convert" the rust to another compound which is more stable, and not corrosive.

Some buildings and bridges are designed with steels that actually use a coating of rust to protect the steel from section loss (rot).

Most cars, especially older classics, were not designed, intended or expected to last 25-30+ years, and as such, rust-proofing was not very important.

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"Once you go RAT, you never go back..."
TC #1366
Tony
The Chevelle (http://www.chevelles.com/showroom/1966_L78/ChevelleA.jpg)
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Iron is a very magnetic element. In fact, iron is stable and abundant in two forms (Fe+2 ferrous and Fe+3 ferric) that is proton heavy. Now, Fe3O3 is what we know as rust. Fe is +2 proton heavy, where oxygen "O" is -2 or electron heavy. Basically, whenever iron is in the presence of excess Oxygen, it is going to grab on to the excess electrons in oxygen to try and get electrically neutral. There is alot of free or loosely bonded oxygen in water. Also, there is a bunch of oxygen in the air around us and like 40% of the earth's crust is oxygen. But in the earth's crust it takes more ion exhange to give up the oxygen than it does with water.
Anyway, this highly magnetic two forms of iron are grabbing all the free oxygen molecules because of the excess electrons. Rust is Fe2O3 if I recall correctly. It's red and flakey. It is also the most abundant combination. What chemists try to do in piping systems is to keep the pH neutral so that all the extra attractions are kept to a minimum. Ideally, the chemists could bombard the Fe3O3 molecule with extra oxygen to create Fe3O4 which is ferric oxide or called black magnetite. The black magnetite is very hard in contrast to rust and also very electrically stable to where once it is formed it doesn't keep attacking the rest of the iron for electrical bonding and perpetuate the rusting process. That is the best I can do without pulling out the old inorganic text books.