Whether post-galvanizing passivation is necessary depends on the intended use and specific requirements.
Not always strictly required
For many standard applications, a simple zinc layer (e.g., achieved through hot-dip galvanizing or electroplating) is sufficient to provide basic corrosion protection. In particular, if the components are not subject to stringent aesthetic or corrosive demands, passivation is often omitted.
Advantages of passivation
- Additional corrosion protection: Passivation processes (e.g., chromating in various colors, phosphating, etc.) create an extra protective layer that shields the underlying zinc from oxidation and extends the service life of the part.
- Enhanced appearance: Depending on the method (blue, yellow, black, etc.), passivated surfaces can offer a more appealing look.
- Reduced risk of white rust: Freshly galvanized surfaces are prone to “white rust” when exposed to moisture or condensation. A passivation step lowers this risk.
Special requirements
In cases where components face extreme environmental conditions (e.g., salt spray, high humidity, aggressive chemicals) or need a defined appearance (such as in the automotive industry or for decorative purposes), passivation or chromating is commonly recommended—or even mandated.
Conclusion
A post-galvanizing passivation is not always mandatory, yet it offers clear benefits in terms of corrosion protection and visual appeal. Whether it is required ultimately depends on the operating conditions and quality demands for the specific part.
