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Metal finishing Q&As since 1989

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Cr6 presence in Trivalent

2004

Dear Sir,

We are doing Zn-Fe trivalent plating for one of our component. We want to check how much of Cr6 presence in our job? And also we would like to know how much of Cr6 presence is allowed in Trivalent. Is there any test procedure for this? Kindly lets us to details.

Regards,

Venkat
plating - Chennai, Tamilnadu, India

GMW3034 is one standard for determination of hexavalent chromium. It is derived from ISO 3613 (section 3.3).

Toby Padfield
Automotive module supplier - Michigan
2004

Mr Venkat

If the spec you follow calls for Trivalent Chromating it should be clear that no Hex is generally tolerated. Your Principal will be the one to admit the deviation/tolerance on this issue. 2) Diphenyl carbazide test is used to verify the presence of Hex Cr in Chromate coats over zinc. There are several other methods and different Principals specify separate tests according to their requirement. You must ask the Principal to specify an acceptable test. This is an ELV issue too.

Regards,

Asif Nurie [deceased]
- New Delhi, India
With deep regret we sadly advise that Asif passed away on Jan 24, 2016
2004

The appearance of Hexavalent and Trivalent passivation is similar. Pl suggest the method to verify Trivalent passivation.

Mohan Malghan
Buyer - Bangalore, India, Karnataka
October 1, 2009