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PVD coating on hinges

 

Dear Sir/s:

We produce continuous hinges 1.5" width x 126" length x 0.6 mm thick from cold rolled steel. They are currently zinc plating followed by yellow chromating. Since we have clients who want their hinges to look like brass to match their Baldwin hardware, we are considering PVD coating for our product:

1. Is it possible for our hinge to be PVD coated to produce gold or brass like finish(zirconium nitride)? Will it peel off due to the flexibility of the product?

2. Do we still have to zinc plate it?

3. Cost comparison, if our current process cost US$1.00 per, how much more would be PVD coating cost us %?

Thank you in advance!

Andrew Kaw
- Valenzuela City, Philippines

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If properly deposited, the PVD coating will not peel off. It is, however, very thin. The industry generally coats first with electroless nickel to provide corrosion resistance, then electrolytic (hexavalent) chrome, then the PVD coating is applied. Zinc plating is an absolute no-no.

Because of all the steps involved, the PVD coating will be more expensive.

Jim Treglio - scwineryreview.com
PVD Consultant & Wine Lover
San Diego, California

Dear Jim:

Thank you for your time. Is it possible for you to explain why zinc plating is an absolute no-no? Or do you have any article or book to recommend for my reference?

Thanks,

Andrew Kaw [returning]
- Valenzuela City, Philippines

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In general, zinc plating is bad for vacuum systems because zinc has a high vapor pressure. If heated even a small amount the zinc gets everywhere, contaminating the system. In addition, ZrN and other decorative PVD coatings are very hard, with very high elastic moduli. Zinc is too soft and flexible as a base coating.

Jim Treglio - scwineryreview.com
PVD Consultant & Wine Lover
San Diego, California
 

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I suggest that you look up the Society of Vacuum Coaters (SVC) who has a number of papers on the subject at their annual meeting and publishes Conference Proceedings. A book of interest is Handbook of Physical Vapor Deposition (PVD) Processing [on Amazon or eBay or on AbeBooks --> affil links].

Donald M. Mattox
Society of Vacuum Coaters
Albuquerque, New Mexico