Corrosion Protection

Using coating is the most common way to reduce corrosion damage on a screw, this kind of coating is considered “corrosion resistant”. Galvanic coatings or zinc thin-layer coatings are often used to protect metal surfaces to increase corrosion resistance.

Galvanic zinc plating
The most common metal coating for screws is galvanization.  This is  a process of applying a protective zinc coating to steel or iron followed by passivation. For galvanizing, the workpieces are put in a zinc electrolyte and chemical reactions that take place in this electrochemical process. During the subsequent passivation stage, it forms an additional protective layer on the metal. Corrosive attacks can be greatly slowed down through the use of targeted post-treatments.

Zinc lamellar coating
Zinc flake coating is a non-electrolytic coating consisting of a  inorganic base coat and top coat. The base coat directly applied to the screws, it provides a very high corrosion resistance. The top coat has additional corrosion protection, it protects against chemical and mechanical influences and is responsible for weather resistance and appearance. The combination of both is called Duplex-coating.

 

 

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