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Bad chromium coverage of nickel products

Hi all,

We are plating chromium on nickel. The problem we have is a bad coverage of the nickel. We use a HEEF chromium bath. Who can help ?

Jan-Henk
- Deventer, Nederland
2002

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First of three simultaneous responses --

Hello, Jan. Step 1: chromium plate a hull cell panel and tell us the bright range. Good luck.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2002

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Second of three simultaneous responses --

Jan-Henk,

Maybe the nickel area is not active, or you have a wrong designate anode. Also the trivalent chrome is high. Try to start the plating with a low current 1,2 A / dm2 for five minutes rise the current to 6,0 A/dm2 for 2 minutes and after that give it a high current strike for 30 seconds. After this reduce the current to normaly CD.

Regards,

Anders Sundman
4th Generation Surface Engineering
Consultant - Arvika,
Sweden
2002

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Third of three simultaneous responses --

Much more information is required to offer you suggestions. What is the analysis of the chrome bath? Temperature? Condition of the anodes? Are the parts going directly from nickel plate, rinses, wet, into the chrome? Are the parts being "staged" in the final rinse causing the nickel to become passive? Maybe the final rinse before chrome plate is badly contaminated. What do the parts after chrome look like?

Bill Hemp
tech svc. w/ chemical supplier - Grand Rapids, Michigan
2002

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HEEF is a functional chromium chemistry and you should be using a decorative chromium chemistry. The functional chemistry typically operates at higher temperature, bad for coverage in decorative chromium plating, and a lower ratio of chromium to sulphate, also bad for coverage. You should talk to your salesperson and get the right chemistry for the job.

George Shahin
Atotech - Rock Hill, South Carolina
2002