How does stainless steel work? You add a little bit of chromium to it and the iron no longer reacts with oxygen? I don’t get how that happens.
In: 2
In two ways:
1. Certain metals interact with oxygen much more vigorously than iron, including chromium and magnesium. Also aluminium. Those metals will corrode preferentially, either as part of an alloy or as “sacrificial electrodes” (something commonly used on ships).
2. A lot of those metals produce tough, continuous and well bonded oxide layers that work to protect the metal from futther oxidation. The whole issue with rusting is that for pure iron and common steel alloys, rust cracks and peels off, because it increases in volume (think ice vs. water). There are special steel formulations that create a well behaved rust layer that is just as protective as the aluminium or chromium ones, and doesn’t need painting.
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