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topic 5504

Alternate Coatings for QQ-N-290


Good afternoon,

The Navy is currently seeking alternative coatings to replace the current electrodeposited nickel plating (per SAE-AMS-QQ-N-290 [link by ed. to spec at TechStreet] , Class 1-corrosion protection, Grade E-0.0006 inch thick) on a spring clip component. The nickel plating is not uniform over the entire component. The spring clip is made of AISI 1075 steel, and has a thickness of 0.0150 ± 0.0005 inch before plating. A fuze plug is inserted into an opening on this spring clip, leading to the eventual detonation of a warhead. The following properties of the spring clip must not be compromised, with the application of the proposed coating:

1. The proposed coating shall provide equal or greater corrosion resistance to the electrodeposited nickel (the current ADL requires a 24-hour salt fog test),

2. The electrical properties of the proposed coating should be similar to that of the nickel coating (the proposed coating shall exhibit a resistivity of approximately 10 - 20m Ohms, maximum) ,

3. The insertion value of the fuze plug should remain consistent with that provided by the nickel, i.e. the coating should not be too thick to hinder the insertion of the plug (the QQ-N-290 nickel at 0.0006-inch thickness was required to provide an insertion force of 5 - 35 pounds.)

4. The coating should be compatible with the soldering requirements (Type SN63 solder, at approximately 375 °F),

5. The coating should be compatible with the potting compound that it is to be encased within (Stycast 2651-40 & Catalyst 11 per MIL-I-16923).

If possible, please propose up to five alternate coatings (aside from electroless nickel which is already being assessed) which may be used in this situation, under these circumstances.

Marc S. Pepi


EN is probably the best from the control standpoint, number of job shops available, and price that meet your criteria. Vapor deposited nickel is certainly worth looking into also.

James Watts
- Navarre, Florida


We are currently providing Ni vapor deposition services for various types of small parts. These parts are solderable and will meet the corrosion criteria.

Mandar Sunthankar
- Fort Collins, Colorado

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