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Hexavalent passivation and RoHS compliance



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Does hexavalent chromating dissipate to not be a recycling problem?

2006

Q. I am currently working at an electronics company in Malta and, apart from forming part of the Environmental Team, I am currently employed as IMDS Co-ordinator. IMDS, is the currently used, globalised system which is required by all Vehicle manufacturers to help identify and eliminate hazardous substances in products and processes used in the automotive industry as well as helping in achieving the ultimate goal of having 95% recyclability of every vehicle by 2015. Our company is in the automotive industry through design and production of automotive controls and switches.
My question is this. We are currently using a commercial solution as a Yellow Passivation (which contains hexavalent chrome) on top of a couple of Zinc plated parts. What I would like to confirm is if this Passivation has any lifetime or not. I have found information saying that such passivation is only intended to last for a limited time of 6 months and it's main use is to protect the Zinc plating from corrosion while the product is still during it's shelf-life. Once the product is assembled this Passivation is no longer required and therefore it degrades and eventually vanishes. Is this correct or it's just a myth?
This is a very important question that I need to answer.

Thanks in advance for your help.

Regards

Daniel Borg
- Qormi. MALTA
^


2006

A. It's Myth, Daniel!

Although I've heard some organizations in the hot-dip galvanizing field claim that the hexavalent chrome dissipates (I doubt it), it is definitely not the case with electroplated parts. The chromate conversion coating protects the zinc from white rust and it is intended to last all the way through the actual service life, not just shelf time. If you look at zinc plated parts in service under the hood, or at lug nuts holding the wheels on, the chromate is still there many years later.

What you must do is specify and use RoHS-compliant trivalent chrome conversion processes (or chrome-free processes), and stop using hexavalent chromated components. Good luck.

Ted Mooney, finishing.com
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
^


2006

A. Hexavalent chromium can outlast a vehicle. It contaminates slag and gases produced when the scrap steel is smelted. Ergo, the ELV limit of 2 grams/vehicle.

Ken Vlach [dec]
- Goleta, California

contributor of the year Finishing.com honored Ken for his countless carefully researched responses. He passed away May 14, 2015.
Rest in peace, Ken. Thank you for your hard work which the finishing world, and we at finishing.com, continue to benefit from.

^



We merged some threads on this page. Please forgive what may look like disrespect towards earlier responses; they probably weren't there :-)



2006

I have tested parts (fasteners like screws made of mild steel) that are Zinc Yellow passivation at a lab that is NABL accredited.
The lab returned a result that confirmed the parts to be RoHS compliant.

Question: Does the Cr6 on the passivation degrade with time to make it compliant with RoHS directives?

If so what is the wait period?

Does this impact the corrosion resistance (5% salt spray)?

Assuming that the lab test is repeatable, can the part be declared RoHS compliant even through the plating shop confirms using hexavalent passivation?

Jithendran T K
Sheet metal fabrication services. - Bangalore, Karnataka,
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2006

This is at least the 3rd time on this site someone has implied here that hexavalent chromates will degrade to non-hexavalent over time. I don't have the lab facility to test old parts for this, so if someone has done so, please reply. But it certainly seems untrue to me, and it seems that were it true we would never have a need to be concerned with EoLV standards and hex chrome, hexavalent chromium in groundwater, etc.

Ted Mooney, finishing.com
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
^


2006

Would like to know more about hexavalent chromium and equipment which can detect it for RoHS. Difference between hexavalent chromium and chromium? how does hexavalent chromium effect products? Does any XRF really detect it?

Saritha Mn
- Thrissur, Kerala, India
^

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