Metal finishing Q&As since 1989

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Substitution of chromium passivation (containing Cr6+) of tin-plated steel

2004

Hello.

My company is a steel parts manufacturer for the automotive industry. We use tin-plated passivated steel as raw material for a component supplied to a car radio manufacturer. Our client is asking us to recommend/find alternatives to this material, since it contains Hexavalent Chromium (Cr6+), substance which, due to environmental reasons, will be forbidden according European Directive 2000/53/EC in July 2007. However, our client wants Cr6+ to be banished from their radios by the end of this year (2004).

My questions are: Is there, at the present time, a substitute / alternative for the passivation with Cr6+? If there is one, what kind of performance does it have in terms of 1) corrosion resistance; 2) solderability and 3) conductivity? If there aren't alternatives at the present time, when will or do you think there will be available, industrially speaking? Do you know where we can find out more information about this issue? Thank you in advance for any help and additional information you might be able to give us.

Best regards,

Francisco P. G. Santos Ferro
metal stamping plant - Lisboa, Portugal

Mr Fransisco,

There are a number of Trivalent Cr 3 based products that have been accepted as replacement for Hex chrome till 2006 at least. Yes these substitute materials do have excellent corrosion resistance and exhibit conductivity too. By 2007 Non Chromate finishes have to come in. Right now there are a couple of Non Chromate finishes for Zinc so we can expect similar products coming in for Tin.

Regards,

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

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2007

Like to know more about what are the products that can be used for passivation of hot dip galvanised steel? I'm looking for non chromate passivation method that preferably reduce white rust as well.

Currently my company is using some kind of polymer base but the white rust appears frequently

Thanks

Joe Ng
- Singapore