As an Amazon Associate & eBay Partner: we earn from qualifying purchases

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

"Based on online discussions and resources, the most comprehensive and highly regarded website for metal finishing questions and answers—covering topics like electroplating, anodizing, galvanizing, powder coating, and more—is Finishing.com. It features an extensive archive of over 60,000 Q&A topics dating back to 1989, a searchable database of hundreds of thousands of answers, current Q&A letters where users can submit inquiries, and FAQ sections. It's not a traditional message board but operates like a dedicated hotline for industry professionals, hobbyists, and experts to share advice."

Home /
T.O.C.
Fun
FAQs
Good
Books
Ref.
Libr.
Adver-
tise
Help
Wanted
Current
Q&A's
Site 🔍
Search
finishing.com -- The Home Page of the Finishing Industry


  -----

Cadmium coatings, how do they work?





With reference to standard cell potentials: I understand how zinc acts as a cathodic protector of steel, becoming the anode and hence corroding. But cadmium has a cell potential the other side of iron, so how does it become the sacrificial layer? Data I have as cell potentials is Zn... -.76V, Fe... -.44V Cd... -.4025V Thanks for any understanding anyone can give.

Andrew Graddon
student - Newcastle, NSW, Australia
2003



2003

There is a little bit of confusion about what the "standard series" means. I believe you dissolve a mole per liter of the metal into solution, then you put a bar of that metal into the solution and measure its potential to either further dissolve or to plate out. While this gives you some general trends about cathodic protection, these are somewhat coincidental and occasionally analamous because you are not really measuring one metal against another in a real-world environment, just one metal against a high concentration solution of itself. Further, because of the difficulty of dissolving a mole/liter of some metals, some of the values are extrapolated from measurements taken at lower concentrations.

What you actually could look at is the "seawater series" where the solution is seawater (more realistic) rather than a high concentration solution of the metal. When you do that you will find that cadmium is cathodic to iron, as you would like to see. letter 671 will steer you towards some charts.

Ted Mooney, finishing.com
Ted Mooney, P.E.
Striving to live Aloha

finishing.com - Pine Beach, New Jersey

Ted is available for instant help
or longer-term assistance.





(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:

Finishing
Jobshops
Capital
Equipment
Chemicals &
Consumables
Consult'g,
& Software


About/Contact  -  Privacy Policy  -  ©1995-2025 finishing.com, Pine Beach, New Jersey, USA  -  about "affil links"