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Alkaline non-cyanide zinc plating problem: Yellow patches
Q. In our company we have used ALKALINE NON-CYANIDE ZINC PLATING. The components are plated in zinc plating bath and then the components are dipped in Nitric acid bright dip bath and blue chrome passivation bath (the blue chrome passivation bath is maintained at the pH range
2.2 to 2.6). Then the finished components are allowed through Hot air dryer for drying.
PROBLEM:
Sometimes yellow lines or yellow shading are obtained in the surface of the components.
- CHENNAI, TAMILNADU, INDIA
2006
A. Nagaraj
If you have not done so already, try rinsing after nitric acid bright dip but before clear chromate.
If your clear chromate solution has chromic chloride in it, use HCl to adjust pH, unless the product bulletin states otherwise.
If you get the stains predominantly at the lower end of your pH range, maintain accordingly.
- Colorado Springs, Colorado
2006
A. YOU HAVE NOT WRITTEN ANY THING WHETHER YOU ARE USING TRIVALENT PASSIVATIONS OR HEXAVALENT PASSIVATIONS.
USE TRIVALENT PASSIVATIONS OF A GOOD CHEMICAL SUPPLIER AND MAINTAIN PARAMETERS AS PRESCRIBED YOU WILL GET DESIRED RESULTS.
THANKS.
Ajay Raina
Ludhiana, Punjab, India
2006
Q. Sir,
I am facing problem of yellowing on alkaline zinc plating in BARREL & VAT Line with trivalent Blue passivation. Please help to solve the problem.
Plating Plant Head - Aurangabad, Maharastra & India
December 10, 2013
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