Rust
(→What is rust?) |
(→What is rust?) |
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There is another iron oxide also known as "rust". It's Fe<sub>3</sub>O<sub>4</sub>. This is also known as "black oxide", or, in mineral form, magnetite. This is the stuff that's left over after using certain products to "convert" rust. Black oxide takes up the same amount of space as iron, so it doesn't bulge it out, like reddish-brown rust, Fe<sub>2</sub>O<sub>3</sub>. Black oxide itself doesn't offer much protection against corrosion, so it's typically covered up (often with [[epoxy primer]]). Black oxide is an example of a conversion coating, a metal coating where part of the surface is converted into the coating itself, by a chemical or electrochemical process. ''(Is this the same thing as blueing?)'' | There is another iron oxide also known as "rust". It's Fe<sub>3</sub>O<sub>4</sub>. This is also known as "black oxide", or, in mineral form, magnetite. This is the stuff that's left over after using certain products to "convert" rust. Black oxide takes up the same amount of space as iron, so it doesn't bulge it out, like reddish-brown rust, Fe<sub>2</sub>O<sub>3</sub>. Black oxide itself doesn't offer much protection against corrosion, so it's typically covered up (often with [[epoxy primer]]). Black oxide is an example of a conversion coating, a metal coating where part of the surface is converted into the coating itself, by a chemical or electrochemical process. ''(Is this the same thing as blueing?)'' | ||
| − | Rust happens more quickly with salt in the air, because salted air is a better electrolyte | + | Rust happens more quickly with salt in the air, because salted air is a better electrolyte, speeding up the electro-chemical corrosion of iron. |
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===Why do older cars rust more than newer cars?=== | ===Why do older cars rust more than newer cars?=== | ||
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