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Need silvery metallic appearance and 150 hours to white corrosion on CRS

2003

We are currently faced with a plating/finishing/coating need which escapes my and my colleagues ability to find a suitable finish.

We are a manufacturer of functional hardware (catches, latches, handles and the like). We have a client that wants us to provide one of our catches plated/coated/finished so that it meets the following criteria:

1) Stainless steel is not an option due to budgetary constraints. Base material will be 1008/1010 CRS.
2) Plating/finish/coating must have a silvery metallic appearance. (Zinc/Nickel has been ruled out.) A bluish tint is acceptable, but nothing more than that.
3) Coating must not yellow with age during a 20 year period spent almost exclusively outdoors. (Hardware to be mounted on farming equipment.) lacquer or other organic finishes are acceptable so long as they do not yellow.
4) Coated/plated catch must survive 150 hours of salt fog spray without white corrosion and 250 hours without red rust.
5) Further the catch must not induce any color changes on the powder coat painted assemblies on to which it will be mounted.
6) Since this is functional hardware there will be small amounts of periodic rotating friction under load while the catch is engaged/disengaged, so whatever coating is chosen should not wear too quickly under this operation.
7) If possible we would like to have components plated in China before final assembly, so commercial availability of a process in China, or the possibility to apply it to an already assembled catch here in the United States is needed.



We are at a loss on this one. Any ideas?

Thank you all in advance,

Will Middelaer
hardware - Hartford, Connecticut, USA

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Dear Mr Will,

Zinc plating will not last in pristine condition for 20 years in an outdoor application. Zinc is used for its corrosive properties not as a barrier coat or topcoat.

Under the circumstances you might want to look at Acid based Zinc - Cobalt with clear Thick Chromating with a final Topcoat of a water based lacquer. May get you past the Salt spray requirement, but still not 20 years.

Khozem Vahaanwala
Saify Ind

Bengaluru, Karnataka, India

2003

Follow up so that readers can know how this problem was eventually solved. Customer opted to bite the bullet and go with (slightly) increased cost of stainless steel part.

William Middelaer
hardware - Hartford, Connecticut USA
2003