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Failure testing of nickel plating

Q. I would like to test the integrity of a nickel plating (IAW MIL-C-26074 [on DLA]E CLASS 2, .0015 MIN THICKNESS) on a part. Please tell me what the MOST harmful environment is for the plating. I need to know what will cause the plating to flake off, wear down, or be destroyed in some other way.

Vince Vendetti
Naval Surface Warfare Center - Dahlgren VA
1998

A. Flaking off occurs as the result of poor adhesion from improper surface preparation; this is probably best tested with a thermal stress cycle, most importantly, just heating the item to a substantial temperature. Wear can be tested with a Taber Abrasion tester.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

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Vinc,

Ted's suggestions are sound- and since MIL-C-26074 has been discontinued and the suggested replacement (AMS2404) is really intended for the automotive industry and is less demanding in terms of physical requirements, you must choose your testing based on the intended service conditions. We employ a bend test of coupons using a 1/2" mandrel. Also, since our parts are subsequently soldered in a vapor phase, we subject the parts (100%) to a vapor phase test (the thermal shock Ted mentioned) to check for blistering. In lieu of Taber abrasion resistance, you could also consider a microhardness test. For corrosive environments, think about CASS or salt spray testing as well.

Good luck.
Keith

Keith Wicklund, CEF-SE
avionics - Minneapolis, Minnesota
1998