No passwords, No popups, No AI, No cost:
we earn from affiliate purchases

Home /
T.O.C.
Fun
FAQs
Good
Books
Ref.
Libr.
Adver-
tise
Help
Wanted
Current
Q&A's
Site 🔍
Search
ted_yosem
Sound technical content, curated with aloha by
Ted Mooney, P.E. RET
Pine Beach, NJ
finishing.com -- The Home Page of the Finishing Industry

  The authoritative public forum
  for Metal Finishing since 1989
  mfhotline


  -----

Flaking of silver on SS




We are using new VCR fittings which have a silver coating (electro-plated)in the inside of the nut to prevent galling between the SS nut and the SS male mating part. We experienced flaking of the Silver and the Manufacturer is claiming that the phosphorous content (resulting from the chemical cleaning) is the cause for the flaking. Flaking is taking place more at where the cleaning occurs than where the threaded part is. I know that Silver is non reactive with Phosphoric Acid. So is it the plating that is defective or is it the phosphoric that is causing the flaking? We tried to dip the nut in the acid for few minutes with an electric current (simulating the cleaning process) but the flaking didn't happen!

Please let me know if you have an answer.

Michael Shaban
- Campbell, California, USA
2002



Hi,

Could you give more details of chemical cleaning and the total pre-plating process please? I have been plating on SS without a problem for quite a few years.

Vijay Deval
electroplaters - Pune, Maharashtra, India
2002



2002

A typical process for plating silver on stainless steel would be:

1. Remove organic soil in an alkaline cleaner. If electrocleaning is used then the parts should be cathodic and the cleaning chemicals completely free of alkaline soluble metals like tin, cadmium, zinc, etc...
2. Cold Water Rinse CWR
3. Hydrochloric Acid Dip
4. Nickel Chloride Strike (Woods)
5. CWR
6. Silver Strike (Low efficiency silver plating solution)
7. Silver Plate.

I was silver plating stainless steel in 1950 and have never heard of using phospharic acid anywhere near the process.

robert probert
Robert H Probert
Robert H Probert Technical Services
supporting advertiser
Garner, North Carolina
probertbanner



2002

We make & break VCR fitting seals every day. We found uncoated 316 gaskets work well, especially if the seal is not going to be subjected to ambient heat greater then the specs for the fittings. I believe the threads on the barrel & connector are silver plated as well, but this is more important then the face seal. You might want to look into VCO fittings; less torque is needed to make the seal in the VCO.

The uncoated seals are 316 stainless. Experiment before making the change, as the process of replacing Welded VCR fittings is messy & time consuming.

Dale Woika
- Bellefonte, Pennsylvania




(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  -  ©1995-2024 finishing.com, Pine Beach, New Jersey, USA  -  about "affil links"