-- 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 5164

Severe Corrosion Problem


We are searching for a coating/infusion that will withstand 5% Sulfuric acid mixed with cetyl trimethyl ammonium bromide. The item to be coated is a 5" dia. cylinder,8" depth, with a flat base welded to one end. Material is 316L S.Stl. There are two 1/2 " ports on the base and one 1/8" port on the side of the vessel.

The vessel is used in laboratory assays to determine fiber content in feeds. The acid solution is poured into the vessel at ambient temp. and a heating band raises the temp. to 100C with 22 psi. The heat cycle is 80 minutes and is repeated up to 8x/day. We would like a 3+ year life. We have tried phenolics, titanium nitride, gold, teflon, and chrome infusion, to name a few.

All coatings suffer from porosity problems which cause a super anode effect on the exposed metal. If anyone has suggestions we are interested. Thanks!

Peter Komarek
- Fairport New York


Peter, You may be taking the wrong approach to the problem in that the coatings you have tried are essentially barriers -- coatings that do not react as readily with the corrosive medium as the base metal. Accordingly, if there is a crack or pore in the coating you set up a galvanic cell.

An alternative is to consider a sacrificial coating, i.e., a coating that is more reactive than the base material, but forms a stable compound when reacted. This is basically what cadmium, zinc, and aluminum do to protect surfaces. You'll need to do some chemistry to come up with some potential materials. After you do, contact me and we can discuss the best way to deposit them.

jim treglio portrait
Jim Treglio
PVD Consultant - San Diego, California


Without coupon testing I would not want to suggest that any given material can withstand this solution, because it's a rather unusual exposure. However, gold does not have to be porous, and I would suggest you have stainless steel coupons gold plated by someone skilled in the art, perhaps to greater thickness than you've tried, and test the coupons under field conditions. There are several nitric acid and nitric fume based tests that should quickly reveal porosity in gold platings.

Ted Mooney, Teds signature
Ted Mooney, P.E.
Pine Beach, New Jersey


From your requirements, i.e., 5% sulfuric acid and cetyl trimethyl ammonium bromide, a logical question might be why not use borosilcate glass? Any scientific glassblower can make this vessel for you, and neither of the chemicals you mentioned will have any effect on it. Borosilicate glass will easily withstand the thermal cycling you outlined.

Drop us a line if you need the name of a glassblower. There are many other coatings which should be able to handle the environment you listed--the name of the game is 100% coverage.

Dale Woika
SCSC - Bellefonte, Pennsylvania


Hi Peter, You can try with a non-porous thick coating, I suggest to try with ECTFE or ETFE. There are some manufacturers of those materials Ausimont (HALAR) Dupont (TFZEL), Withford (Dycor), Daikin, etc. You can contact with a teflon coater, they will help you.

Jordi Pujol
- Barcelona, Spain

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.