Aloha, fun & authoritative answers -- no cost, no registration, no passwords, no popups
(as an eBay Partner & Amazon Affiliate we earn from qualifying purchases)

Home /
Site 🔍
pub  Where the
world gathers for metal finishing
Q&As since 1989


Control the phosphate % in EN deposit layer

In the production of EN on brass substrate, I found that the phosphate deposit content is vary from 3% to 9%. I want to know how to control the phosphate deposit in ~8-9%. If anyone know, please reply to me. The bath operation data is stated as below, Ni content 5-6g/lt Sodium hypophosphite ~30g/l Operation Temp 90C Bath Life cycle maintain up to 8 MTO.

Thanks for your attention.

David Koo
- China

You didn't mention it, but pH of solution, specially close to the surface, is one of the more important variables to affect P in the deposit. Obviously, the type of complexors and buffers play the important role in this variable. Too complicated a question to be fully answered in a forum like this. You should contact your vendor.

Guillermo Marrufo
Monterrey, NL, Mexico


Dear David,

Guillermo is correct, you should contact your supplier. If the P content varies so much, then there is something wrong with the chemistry.


Jonatha Timms
- Hong Kong


Ok lets see how far I can get my foot in my mouth. My EN work is 15 years old. The deposition of N is thermodynamic controlled and the P is kinetic, or maybe I have it backward. Any case as you increase plating rate the amount of P co-deposited goes down. Also(help someone) does not an aged bath tend to have a higher P?

So while the world demands fast turn around at a cheap price, good EN wants a slower deposit rate to have higher P. Either case I got out of the EN market as I saw an engineering coating being applied with too much demand on bright and shinny.....Fast rate= low P = poor corrosion protection.

Bright coating = coating with more voids and hence poor corrosion protection. (Thiourea [on eBay or Amazon], Cd)

Jon Quirt
- Minneapolis, Minnesota

(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:

Chemicals &
Consult'g, Train'g
& Software

About/Contact  -  Privacy Policy  -  ©1995-2024, Pine Beach, New Jersey, USA  -  about "affil links"