The Many Faces of Corrosion Inhibitors

Yesterday I noted with sadness the demise of one of our feeding bowls. We bought the bowl believing it was treated with a corrosion inhibitor, but the evident rust inside and out from holding mineral salts proved otherwise. Corrosion destroys or impedes the operation of many simple and complex machines, and, for this reason, corrosion inhibitors have become specialized in their uses.

Corrosion is defined as the gradual destruction of metals or other materials by a chemical reaction. Provided by water treatment chemical supplier, corrosion inhibitors adhere to the surface of metals to create a film between the metal and the surrounding environment and impede chemical reactivity. To inhibit corrosion, five specific methods have been used with success.

  1. Passivators Inhibitors: Passivators, or passivity inhibitors, reduce the ionic charge of the metal they protect to a more stable molecular structure. When the metal becomes less charged and more passive, it is less reactive to outside chemical changes. The most common passivators are oxidizing agents.

  2. Cathodic Inhibitors: Cathodic inhibitors reduce hydrogen’s loss as well as its ability to recombine with external molecules, thereby “sealing” metals.

  3. Organic Inhibitors: Organic inhibitors form a hydrophobic (water fearing) film on the surface of metals. Organic inhibitors containing both nitrogen and sulfur promote better bonding and are recommended; weaker bonds are formed when other molecules are used and the underlying metal is not sealed as well.

  4. Precipitation Inducing Inhibitors: Precipitation inducing inhibitors cause a precipitate, or a solid, to form via a chemical reaction. This precipitate amalgamates with the metal to form a protective barrier.

  5. Volatile Corrosion Inhibitors: Volatile corrosion inhibitors (VCIs) are a unique corrosion inhibitor, to say the least. VCIs emit a vapor that contains nitrogen. While one side of the nitrogen bonds to the polar metal surface, the other hydrophobic side points externally and repels water. The distinct difference between VCIs and other corrosion inhibitors is its ability to evaporate and redeposit molecules to evenly coat the entire surface of a metal object. This also causes VCIs to be self-healing: any surface that is marred or scratched will heal by the redistribution of existing VCI coating.

Depending on the type of metal and your individual requirements, one of the above choices of corrosion inhibitors is sure to meet the needs of your corrosion control. If you’re looking to purchase corrosion inhibitors, or require more information, contact Bell Chem at 407-339-BELL (2355). We’re a professional water treatment chemical supplier in Central Florida and we’re happy to help with you next order.

How have corrosion inhibitors helped you? Share this post and tell us which method of inhibitor you have experience with.