Alternative for nickel plating of fasteners
We currently barrel plate with bright nickel, cap screw fasteners - primarily for decorative purposes. We have addressed the question of hydrogen embrittlement and get reasonable results. My question is what are the alternatives to this process that would give better corrosion resistance for our fasteners. We need the bright finish, and we need it to stay bright in an exterior environment. Is chrome plating the only alternative? What other options are there?
Thanks in advance,Hamish Hawthorn
components - Sydney, Australia
As you probably know, conventional barrel plating is not very successful on chromium plating because make-and-break contact spoils chrome plating. So chrome plating will probably prove cost-prohibitive because of the labor cost of racking. There have been some cobalt and other "chrome substitutes" touted by the large proprietary vendors, and since color match would not be a major issue for fasteners, that may be the way to go. Try Enthone-OMI or Atotech or Macdermid.
Ted Mooney, P.E.
Pine Beach, New Jersey
Dear Mr. Hawthorn
A response to your problem of decorative and corrosion resistant cap screw fasteners is the plating over bright nickel ( of sufficient thickness i.e.10 - 15 µm ) of a thin coating ( 0.5 - 2 µm ) of tin-nickel alloy ( 65 % Sn-35 % Ni) which has the same corrosion resistance as chromium, a hardness of 650 HV, a pink tint and can be applied in barrels.
Best regards,Emmanuel Popesco
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