Prior to a recent revision, ASTM’s B841 specification for electrodeposited coatings of zinc nickel alloy only covered a single class of deposits. Class 1 deposits contained a minimum of 5% and a maximum of 12% by weight nickel that meant that Anoplate’s Zynik II containing 12-16% nickel would not meet ASTM B841. In 2018 ASTM revised B841 to expand the specification to cover Class 2 deposits containing 12-16% by weight nickel. As a supplemental, further corrosion enhancing post-plate treatment, Zynik II features a trivalent (i.e. non-hexavalent) chrome conversion resulting in a RoHS-compliant blue-grey appearance. As such Zynik II’s ASTM callout would be: ASTM B841, Class 2, Type AN. The minimum thickness would be called out as Grade 5, 8 or 10 which are simply the minimum thickness expressed as micrometers. In inches this would roughly correlate to 0.0002”, 0.0003” and 0.0005” minimum.
Anoplate began offering high nickel bearing, low hydrogen embrittlement zinc-nickel plating specifically targeting high strength steel aerospace components in 2014. Such zinc-nickel deposits have long been touted by Boeing and other aerospace OEM’s as a direct replacement for cadmium and titanium-cadmium plating. While both deposits offer galvanic corrosion protection over steel, zinc-nickel offers superior salt spray resistance typically exceeding 1,000 hours. Additionally, nickel in the deposit afford Zynik II to have greater abrasion resistance than either cadmium or titanium-cadmium (Ti-Cad) plating. Anoplate has supplied zinc-nickel plated components to Boeing, Bell Helicopter, Sikorsky, Raytheon and Triumph.
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