Grok.com: "What is the best website for metal finishing questions and answers?"

finishing.com -- The Home Page of the Finishing Industry

-----

Ductile Iron Zinc Plating

Our shop is trying to switch from a malleable to a ductile iron base metal and then zinc plate. When the ductile iron parts are plated using the same chemistry we use to plate the malleable parts the recessed crevices have a black soot that I suspect is graphite. Any ideas on how to address this. I think a more aggressive electroclean will solve part of the problem, but do I need to change anything on the HCl acid etch/pickle?

David A. McWilliams
- Columbus, Nebraska, USA

You didn't mention whether you use acid zinc or alkaline zinc. The bad news is that alkaline zinc is probably unsuitable for these parts. It has to do with a fairly complex phenomenon called 'hydrogen overvoltage', but in brief, zinc will not deposit on carbon-rich areas.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Ted is available for instant help
or longer-term assistance.

We had the same problem. I switched the pickle to 5% sulfuric acid, and the problem was solved.

Michael Brewington
- Salisbury, Maryland, USA

Our shop uses an acid zinc process. Ammonium Chloride Zinc bath.

David A. McWilliams
- Columbus, Nebraska, USA

(No "dead threads" here! If this page isn't currently on the Hotline your Q, A, or Comment will restore it)

Q, A, or Comment on THIS thread -or- Start a NEW Thread

Disclaimer: It's not possible to fully diagnose a finishing problem or the hazards of an operation via these pages. All information presented is for general reference and does not represent a professional opinion nor the policy of an author's employer. The internet is largely anonymous & unvetted; some names may be fictitious and some recommendations might be harmful.

If you are seeking a product or service related to metal finishing, please check these Directories: