-- The Home Page of the Finishing Industry
23+ years of serious education, promoting Aloha,
& the most fun you can have in metal finishing smiley
    no popups, no spam
on this site
current topics
topic 10450

Electroless nickel acid resistance


I have an electroless nickel plated shaft. It is part of an assembly. The remaining assembly is steel and flash rusts during strorage. Prior to painting we use a phosphoric acid to remove the rust. This is applied to the steel portion of the assembly. It is possble, of course, that the operator inadvertantly splash some Phosphoric acid on the EN. We are at about 20% acid. Would this damage the plate? The dwell time is only 5-10 mins.

Kelly Draper
- West Plains, Missouri, USA


It sounds like you are applying a phosphate coating prior to painting. If not, it might be a good idea for paint adhesion. It should be fine, but you could try a sample, and inspect the EN after painting. How thick is the EN coating, does it get masked before painting?

tom pullizzi portrait
Tom Pullizzi
Falls Township, Pennsylvania



We are not trying to phosphate, just trying to remove rust. There are no accelerators or other additives in the phos. (We do use a organic vynil wash primer pretreatment prior to paint.) The EN coating is 2 mil thick, and yes it does get masked before coating. A visual inspection does not indicate any difference before to after. I have also had an SEM-EDS performed on the exposed side and the interface side and there is a higher phos concentration on the interface side, so we are not getting any diffusion into the surface during the process. (I believe...)

Thanks for your input!

Kelly Draper
- West Plains, Missouri, USA



High phos electroless nickel (10% min P) dissolves at a rate of approx. 0.1 mil per year in phosphoric acid at 85% at 20 deg C. Lower phos nickels are not as resistant. I hope this will help you find yourself the answer?

Guillermo Marrufo
Monterrey, NL, Mexico

This public forum has 60,000 threads. If you have a question in mind which seems off topic to this thread, you might prefer to Search the Site

ADD a Comment to THIS thread START a NEW threadView CURRENT TOPICS

Disclaimer: It's not possible to 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 may be deliberately harmful.

  If you need a product/service, please check these Directories:

JobshopsCapital Equip. & Install'nChemicals & Consumables Consult'g, Train'g, SoftwareEnvironmental ComplianceTesting Svcs. & Devices

©1995-2018, Inc., Pine Beach, NJ   -   About   -  Privacy Policy
How Google uses data when you visit this site.