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Elimination of Hexavalent chromium in yellow passivation

2003

We are using Yellow passivated components which inhibits Hexavalent Chromium. Now we are in the process of eliminating Hexavalent chromium and converting them to Trivalent.
We have trichrome HB2000 for white passivated / Zinc plating, but did not find any solution for Yellow passivation in Chennai locales.

So kindly advise me on how to convert/ divulge from Yellow hexavalent chromium. Also tell us some details / website from where we can know about the properties, structure and effects of hexavalent chromium and how far the trivalent chromium is advantageous . harmless as against the hexavalent one.

B.Vinodh
Chennai, Tamil Nadu, India

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2003

Mr Vinod,

1) Trivalent chrome coatings are , by nature blue bright or whitish.
2) Yellow / Rainbow iridescent is the color of Hexavalent chrome passivation.

World wide QA and QC managers have come to accept both the above phenomenon as a norm. .

Therefore if for any reason you are looking for a yellow Trivalent coating to satisfy buyer misconceptions, there are processes that incorporate a yellow compatible dye.

Trivalent coatings usually last longer in Salt spray than Hexavalent coats. Especially the Blue bright coating which goes for 120 hrs vs Hex that fails in 24.

Regards,

Asif Nurie [deceased]
- New Delhi, India
With deep regret we sadly advise that Asif passed away on Jan 24, 2016

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Have you tried calcium polysulfide? Calcium Polysulfide also known as Lime Sulfur has been proven to successfully treat heavy metal containing waste. Specifically, Chromium (VI) can be reduced to Chromium (III) very efficiently using calcium polysulfide.

Best Regards,

Chirag Tilara
- Rajkot, Gujarat, India
2006