finishing.com -- The Home Page of the Finishing Industry
no_pop_no_spam
HomeFAQsBooksHelpWantedsForum  letter 60294

Serious Education ... plus the most fun you can have in metal finishing.

Can Type II Chromate be done on Mechanical Galvanizing?


October 14, 2016

I have a client who wants bolts to be mechanically galvanized to ASTM B695-85 Class 50 Thickness (minimum), with Type II Chromate Treatment.

Can you do chromate treatment on galvanized surface?

Thanks

Atanu Bose
- New York, New York
contact


October 17, 2016

A. First of all, the answer is yes. Now for the editorial comment. Most mechanically galvanized articles are not chromated because that is the practice for hot dip. But chromating offers fantastic 'bang for the buck.' And the post application of a silicated 'sealer' can get a mechanically galvanized/chromated/passivated article well over 1000 hours of salt spray. Of course, yellow or olive drab chromates are not ROHS-compliant. There are ROHS-compliant alternatives.

tom_rochester
Tom Rochester
Plating Systems & Technologies, Inc.  

Jackson, Michigan, USA



December 21, 2016

Q. I must assume that any surface that has been zinc plated and pure zinc metal can also be coated with a chromate coating correct?

Marvin Sevilla
- Managua, Nicaragua


December 23, 2016

A. That is correct. Mechanical galvanizing is a deposit that is approximately 95% zinc and 5% tin, and all conventional chromates work on it.

tom_rochester
Tom Rochester
Plating Systems & Technologies, Inc.  
Jackson, Michigan, USA



What metals can be electrolytically chromated?

December 25, 2016

Q. Thanks for responding back, I wonder if one could chromate other metals by applying a low current and stainless steel anode.

Marvin Sevilla
- Managua Nicaragua


Electrolytic and Chemical Conversion Coatings

December 2016

Hi Marvin. Chromating of other metals probably has ever decreasing utility because of RoHS and similar requirements which limit the presence of hexavalent chromate on components. Further, the chromate coating may not function quite the same way on other metals as it does on zinc. But yes, chromating of copper and silver is not even uncommon; I designed a tin-zinc plating line that incorporated electrolytic chromating; and according to Biestek & Weber =>
it is even possible to electrolytically chromate nickel, chromium, steel, stainless steel, titanium, and zirconium.

Regards,

pic of Ted Mooney
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey

ADD a Q or A to THIS thread START a NEW THREADView This Week's HOT TOPICS

Disclaimer: It is 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; 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. & DevicesUsed & Surplus


©1995-2017 finishing.com     -    Privacy Policy
How Google uses data when you visit this site.