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RE: Alternative for Lead Anodes in Chrome Electroplating



Hi Michelle,
 
I'm not sure about fluoride in Ti anodes but I did find reference on the internet to the use of platinized titanium anodes.  While platinum is very expensive, the Ti provides strength and support so that only a thin layer of Pt is required.  In the aerospace industry, the High Velocity Oxygen Fuel (HVOF) Thermal Spray process has been looked at as a replacement for hard chrome.
 
If you do switch anode materials, keep in mind that you might need to provide some other means to control trivalent Cr.  Lead anodes are attacked and a layer of lead chromate (yellow-orange) forms when they are left in the tank with the current off.  When in use, the lead chromate converts to lead peroxide (brown). Too much lead peroxide is harmful in that it changes the physical size of the anode but some peroxide is good because it reoxidizes the trivalent Cr to hexavalent Cr.  This info comes from Durney's "Electroplating Engineering Handbook."
  
Mike Callahan, PE
Jacobs Engineering
1111 S. Arroyo Parkway
Pasadena CA 91105
Business: (626) 568-7005 
 
-----Original Message-----
From: owner-p2tech@great-lakes.net [mailto:owner-p2tech@great-lakes.net]On Behalf Of michelle gaither
Sent: Tuesday, February 05, 2008 1:30 PM
To: p2tech
Subject: Alternative for Lead Anodes in Chrome Electroplating

Looking for experience or referrals to an alternative anode or process for hard chrome plating of mild steel? 
 
Currently, a dual-catalyst system is used, with lead anodes (over 90% lead).
 
Are there other anodes that might work in this application?  apparently Titanium anodes contains fluoride, which may not work for this process?  Is anyone using vapor deposition for this application or similar application?
 
Thanks in advance.
 
 
Michelle Gaither
Technical Research Coordinator
Pollution Prevention Resource Center
www.pprc.org

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