The secret of aluminum and stainless steel’s resistance to corrosion is called passivation: a chemical process that builds a microscopic layer of nonreactive material between the aluminum or stainless steel work surface and the air. Stainless steel’s passivation process occurs due to its chromium content. When exposed to air, stainless steel produces a layer of chromium oxide a few atoms thick. The passivation layer is just a few atoms thick and is oxygen and water resistant. Generally, the higher the stainless steel’s chromium content the more resistance it offers to the elements, thanks to a more robust passivation layer.

Passivation is a natural characteristic of pure aluminum. Aluminum oxide accumulates on the surface of the metal, halting further corrosion. Be careful – Aluminum alloys do not necessarily have this characteristic, so they can actually be less corrosion resistant, depending on the exact alloy used. In many instances, aluminum is often applied as a thin layer to impart corrosion resistance to other materials.

Various processes can improve passivation but it is never 100% effective. For example, regular abrasion can remove both materials’ passivation layers, making them vulnerable to corrosion, though this normally requires a significant amount of wear and tear. In addition, submersion, galvanic reactions and other circumstances and eliminate the layer. For the most part, these situations fall outside the scope of typical use.

If you have any questions about the aluminum, stainless steel and other materials we use in custom industrial workbenches, lab tables or anything else, don’t hesitate to Contact RDM. We’re happy to answer your questions.

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