How does a relatively small amount of chromium prevent steel from rusting?
In: 573
If you are talking about chrome plating, the oxidization of chromium produces Cr203 which is really hard and prevents oxygen molecules from water from seeping below and oxidizing the iron or steel.
Iron oxide is flaky and oxygen molecules easily get to deeper layers of metal lattice. The deeper that goes the more weak the metal gets. If you have mixed iron and chromium (among others) into iron to make a steel alloy, then the same principle happens but it is distributed amongst the metals bonds. The chromium oxidizes and provides protective attributes. If you have enough chromium in the alloy it will be enough to prevent the iron from oxidizing to the point where it weakens.
Stainless steel will oxidize, and eventually it will oxidize to nothing, but it takes forever and the oxidization on the surface will be far less troubling than other steels or irons. Stainless steel now has some competition, there are iron / steel alloys now that will oxidize a hard external layer into a soft brown color which is hard like chromium but less expensive than chrome plating.
Latest Answers