AMS-2404C, AMS-2505B, AMS-2433B,
Similar to stainless steel in color. Plates uniformly in recesses and cavities (does not build up on edges) sometimes called "Dog-boning". Corrosion resistance is good for coatings over .001" thickness. Electroless nickel is used extensively in salvage of mismachined parts. Also, for inside dimensions and irregular shapes (where assembly tolerances need uniformity provided by electroless process). Coatings typically used to provide a hard-ductile, wear-resistant and corrosion-resistant surface for operation in service temperatures up to 1000F (538C). Previously Mil-C-26074 was the industry specification.
Please note: The following is per. Mil-C-26074. This specification has been cancelled but, is still used in industry.
Class 1 As coated
Class 2 Steel and other base metals heat treatable to improve hardness.
Class 3 Aluminum and other base metals not heat treatable
Class 4 Aluminum alloy, heat treatable, processed to improve adhesion of the nickel deposit
Grade A .0010" min. Aluminum alloys will be grade A.
Grade B .0005" min.Cu, Ni, Co alloys will be grade B.
Grade C .0015" min. Ferrous alloys will be grade C.
Electroless Nickel - AMS-2404D / AMS-2405B
These AMS specs are similar. Ams- 2404D does not specify the phosphorous content while the
AMS - 2405B says "P" to be 8% max. No specific hardness numbers defined by these two specs on the EN deposit.
AMS-2404D Thickness as specified on drawing. Note: Unless a specific class is specified,
Class 1 shall be supplied.
Class 1 Except for hydrogen embrittlement relief, no postplating thermal treatment.
Class 2 Thermal treatment at 450 F (232 C) or above to harden the deposit.
Class 3 Thermal treatment at 375 F (191 C) to verify adhesion for non-heat treatable aluminum and beryllium alloys.
Class 4 Thermal treatment at 250 F (121 C) to verify adhesion for non-heat treatable aluminum alloys.