Trivalent chromium vs hexavalent chromium How to choose color zinc passivation solution?

Trivalent chromium vs hexavalent chromium How to choose color zinc passivation solution?

Tue Dec 19 15:57:25 CST 2023

When using color zinc passivation solution, what should I choose between trivalent chromium and hexavalent chromium? What are the advantages and disadvantages of each compared to the other? Let's discuss this issue in this article.

Corrosion resistance of passivated film

Trivalent chromium

After the use of color zinc passivation solution, because the traditional trivalent chromium passivation process does not have the ability to self-repair, if the passivation film is damaged, then corrosion will quickly occur, and it must be closed to improve the corrosion resistance of the salt spray. The corrosion resistance of chromium-trivalent color passivation film and chromium-trivalent black passivation film is weaker than that of chromium-hexavalent passivation film.

Hexavalent chromium

If the hexavalent chromium passivation process is used, then the resulting film will generally have strong corrosion resistance. When the passivation film is scratched, because this kind of passivation film has the ability to repair itself, its corrosion resistance will not deteriorate.

In recent years, with the rapid development of China's automobile industry, higher requirements have been put forward for the performance, service life, aesthetics, environmental protection and other aspects of auto parts.

Automobile lock as a key auxiliary parts of the automobile, its existing surface treatment process has three chromium color zinc passivation process and six chromium color zinc passivation these two kinds of plating, due to environmental reasons, now people prefer to use three chromium color zinc passivation process, but as previously said, three chromium color zinc corrosion resistance is not as good as six chromium. Then in the face of the high salt spray requirements of the surface treatment of auto parts, the electroplating factory will inevitably be unable to cope with.

What should I do if I can't meet the customer's requirements and can't get the order?

Don't worry, at this time you can use Bigely's trivalent chromium color zinc passivation solution BZ-207, not only can obtain a deep color yellow passivation film similar to hexavalent chromium passivation, but also good corrosion resistance, when the thickness of the galvanizing layer is 5-8 microns, the neutral salt spray test after passivation starts for 150 hours. You know, hexavalent chromium color zinc passivation may not be able to achieve this data.

If you are interested in color zinc passivation solution, please contact us for samples and technical support.