Chromium VI-containing chromates

1. Characteristics and properties

Chromium-VI-containing chromates contain chromium-VI ions, which are stored in the applied layer. Up to a certain point, these ions cause a self-healing effect of the layer when the surface is damaged, e.g. by a light stone impact. Chromating zinc layers considerably improves corrosion protection.

The corrosion protection can be further increased by subsequent passivation of the chromated layers in polymer-containing solutions. The test methods for corrosion protection of chromated zinc coatings are defined in DIN 50960 and DIN 50961. Chromium VI-containing coatings are not RoHS compliant.

2. Benefits and areas of application

Chrome-VI-containing chromates are ideally suited for mass-produced articles such as screws and fasteners as well as for all workpieces which, in addition to excellent corrosion protection, are intended to achieve a decorative and attractive appearance. Currently, yellow iridescent, olive and black chromates are available for this purpose.

3. Basic material

Chromating is applied directly to galvanized components.

4. Required delivery condition

The goods provided must be largely metallically bright. Residual oils or residual impurities must be removable with conventional aqueous alkaline degreasers. Oils containing silicone, alkali/alkaline earth and high-pressure additives must be avoided at all costs.

5. Pre-treatment

Chromating is applied directly after zinc coating.