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Theoretical understanding of hard chrome plating

October 17, 2008

What is the current status of theoretical understanding of hard chrome plating based on Cr6 ?

The mechanisms of hydride production ? The cracking as a result ? The decomposition of hydrides ? The BCC Cr ?

How do the bath parameters achieve the desired results for conventional hard chrome plating ? Using various catalysts such as : Sulfuric, fluoride, complexed fluorides, etc. ?

What is the mechanism of thin dense chrome ? Such as the one touted by Armoloy ?

What is the cause of the nodules? What are the conditions, etc. Why thin dense chrome up to 7/10 mil or even 1mil = 1/1000 inch is not cracked ?

What is current status of understanding of catalytic anions such as sulphate, fluoride, etc.

Thank you.
Are there any trivalent baths comparable to the hard chrome 6?
Are there other metal plating baths of equal properties , hardness and lubricity from nodular surface etc. ?

Yanoush Greek
electrochemist - Greece

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October 23, 2008

A paper by N.V. Mandich presented at AESF 82
Technical conference, SurFin 95 (Baltimore, MD, June 1995) gives a comprehensive "Chemistry of Chromium"

The paper should be available from AESF, now called NASF
1155 Fifteen Street NW,
Suite 500
Washing DC 20005

Telephone 202-457-8404, FAX 202-530-0659 (www.nasf.org)

Don Baudrand
Consultant - Poulsbo, Washington
(Don is co-author of "Plating on Plastics" [on Amazon or AbeBooks affil links]
           and "Plating ABS Plastics" [on Amazon or eBay or AbeBooks affil links])

Just to add that there is at least one company that claims to have a proprietary process to plate tri chrome as hard as Cr6 and even harder. It is a brush plating company by the way. G. Marrufo-Mexico

Guillermo Marrufo
Monterrey, NL, Mexico
October 27, 2008

Unless there is something very recent, Tri-chrome brush plating is limited to a very thin coating. OK for decorative, but not thick enough for "hard" chrome or "functional" chrome.

James Watts
- Navarre, Florida
October 28, 2008