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Q & A: Effects of rust

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Q:
What are the effects of rust?
- Anonymous
A:
Metals containing iron, such as most kinds of steel, will rust when exposed to air and water. Rust is just iron oxide, usually with water molecules incorporated in it too. It usually takes the form of an orange powder on the surface of the metal. Other metals oxidize or form other compounds in a similar way, although we usually say they corrode. Rusting is a specific kind of corrosion which applies to iron-containing metals.

Rusting has a number of effects on metal objects. It makes them look orange and rough. It makes them weaker, by replacing the strong iron or steel with flaky powder. Some oxides on some metals such as aluminum form just a thin layer on top which slows down further corrosion, but rust can slowly eat away at even the biggest piece of iron. If a piece of iron's strength is important for safety, such as a bridge support or a car's brake caliper, it is a good idea to inspect it for rust damage every now and then.

Rust also can cause metal parts that are supposed to slide over one another to become stuck. Just ask someone who has tried to get a rusty nut unstuck from a rusty bolt.

Rust can make holes in sheet metal. Rusty car mufflers sometimes develop holes in them, and the sheet steel making the outer bodies of cars will often rust through, making holes.

Rust is a lot less magnetic than iron. An iron magnet will probably still work almost as well when it has a thin coating of rust on it, but if it has rusted so badly that most of the metal is gone, then it will not work very well as a magnet.

Rust is an insulator, meaning that it doesn't conduct electricity easily, unlike iron, which is a metallic conductor. So if some electrical connection is made with iron, it's likely to go bad when the iron surface rusts.

Tom J. (and mike)

(republished on 07/13/06)

Follow-Up #1: What are the environmental impacts of rust?

Q:
what are the enviromental impacts of rust
- abebe
jimma
A:
Rust is formed when an iron surface is exposed to oxygen in the presence of moisture. Several varieties of iron-oxides can form.   Rust is non-toxic and so presents no biological hazards.  The main environmental impacts of rust is the degradation of steel and iron structures, such as bridges, automobiles, etc.  My ancient car seems to be particularly vulnerable.

LeeH

(published on 12/14/10)

Follow-up on this answer.