Home /
T.O.C.
FAQs
 
Good
Books
Ref.
Libr.
Advertise
Here
Help
Wanted
Current
Q&A's
Search 🔍
the Site

World's #1 finishing resource since 1989
No login needed: Chime right in

topic 59029

Can Citric or Nitric Passivation Be Done on Both Series 300 and 400 Stainless?



November 5, 2012

Q. I work in the medical device industry and my firm is currently reviewing our passivation procedure. We are referencing ASTM 967 and would like to use the chart in the ASTM as a guide, but not a mandatory requirement. Would it be a correct statement that all 300 and 400 series SS and also 17-4 can be passivated using any of the Citric or Nitric processes? The ASTM seems ambiguous in the fact that it doesn't define specifically what process to use but to use it as a guide. Thanks!

Shawn Tribolet
- Warsaw, Indiana


December 3, 2012

A. SS300 & 400 can be passivated by pickling with heating nitric acid 72 degree baumé as concentrated using chromic acid @ 1% on total volume (which acts as an INHIBITOR). If you are using citric acid you should use (EDTA) based INHIBITOR. THE INHIBITORS using avoids hydrogen embrittlement, resulting in good corrosion resistance. Both citric acid/Nitric acid are also has to be heated for 15 to 30 minutes to get perfect passivation. Using Nitric acid is best.

C PRAKASHAM
CONSULTANT- Chennai, Tamilnadu, South India


December 4, 2012

A. Shawn,
For nitric passivation, you very much should pay attention to the chart used by ASTM A967 / AMS 2700 / QQ-P-35. Bad combinations of bath formulation and stainless grade can result in destroyed parts and/or runaway reactions producing clouds of toxic gas.

Citric passivation is much more forgiving. A low pH bath can sometimes cause some light surface etching to non-300 grades, but a citric bath with a raised pH is generally good for all grades.

adv.
Let us know if we can help.

- - -

Mr Prakasham,
I don't think you are familiar with passivation or are using the word inhibitor properly.

ray kremer
Ray Kremer
Stellar Solutions, Inc.
supporting advertiser
McHenry, Illinois
stellar solutions banner


December 6, 2012

A. The problem of medical parts passivation can be solved easily by switching to alternative passivation technique. It is hard to persuade people to alter their existing methods.

adv.
We are giving away (for small fee) one of such passivating electrolytes with the condition that the receiver of such process will keep it confidential, and provide the testing results and his opinion on this web site. Contact me if interested.

anna_berkovich
Anna Berkovich
Russamer Lab
supporting advertiser 
Pittsburgh, Pennsylvania 
russamer labs banner

none
finishing.com is made possible by ...
this text gets replaced with bannerText
spacer gets replaced with bannerImages

Q, A, or Comment on THIS thread SEARCH for Threads about ... My Topic Not Found: Start 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:

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


About/Contact    -    Privacy Policy    -    ©1995-2021 finishing.com, Pine Beach, New Jersey, USA