Military Plating Specifications

		Process	Mil. Spec.	Thickness	Comments
	Gold	Yellow to orange color depending on proprietary process used. Will range from matte to bright finish depending on basis metal. Good corrosion resistance, and has high tarnish resistance. Provides a low contact resistance, and is a good conductor. Has excellent solderability.	MIL-G-45204B Type I Type II Type III Class 00 Class 0 Class 1 Class 2 Class 3 Class 4 Class 5 Class 6	Unless otherwise specified 0.00002" min. 0.00003" min. 0.00005" min. 0.00010" min. 0.00020" min. 0.00030" min. 0.00050" min. 0.00150" min.	99.7% gold min. 95.5% gold min. 99.9% gold min. Grade A 90 Knoop max. Grade B91-129 Knoop Grade C 130-201 Knoop and over Type I (Grade A, B, or C) Type II (Grade B, C, or D) Type III (Grade A only)
	Silver	White matte to very bright in appearance. Good corrosion resistance, depending on base metal. Will tarnish easily. Hardness varies from about 90 Brinnel to about 135 Brinnel depending on process and plating conditions. Solderability is excellent, but decreases with age. Best electrical conductor. Has excellent lubricity and smear characteristics for anti-galling uses on static seals, bushings, etc.	QQ-S-365C Type I Type II Type III Grade A Grade B	.0005" min. unless otherwise specified.	Increasing use in both decorative and engineering fields, including electrical and electronic fields. Matte. Semi-bright. Bright. Chromate post-treatment to improve tarnish resistance. No chromate treatment.
	Electroless Nickel	Similar to stainless steel in color. Plates uniformly in recesses and cavities (does not build up on edges). Corrosion resistance is good for coatings over .001" thickness. Electroless nickel is used extensively in salvage of mismatched parts. Also, for inside dimensions and irregular shapes (where assembly tolerances need uniformity provided by “electroless” process).	MIL-C-26074B Class 1 Class 2 Class 3 Class 4 Grade A Grade B Grade C	Unless otherwise specified. .001" min. .0005" min. .0015" min.	As coated. Steel and other base metals heat treatable to improve hardness. Aluminum and other base metals not heat treatable. Aluminum alloy, heat treatable, processed to improve adhesion of the nickel deposit. (For severe corrosion protection).
	Tin	Color is gray-white in a plated condition. Had very high luster in fused condition. Soft, but is very ductile. Corrosion resistance is good. (Coated items should meet 24 hour 5% salt spray requirement.) Solderability is excellent. Tin is not good for low temperature applications (changes structure and losses adhesion when exposed to temperatures below -40º C). If a bright finish is desired to be used in lieu of fused tin, specify Bright Tin plate Thickness can exceed that of fused tin and deposit shows excellent corrosion resistance and solderability.	MIL -T-10727B Type I Type II	As specified on drawing. Thickness Guide (not part of Spec.): .0001"-.00025" .0002"-.0004" .0003" min. .0002"-.0006"	Electrodeposited. Use ASTM B 545 Standard Specification. Hot dipped. Flash for soldering To prevent galling and seizing. Where corrosion resistance is important. To prevent formation of case during nitriding.
	Tin Lead	Either a matte or bright luster is acceptable. Has excellent solderability.	MIL-P-81728A 60/40	Unless otherwise specified. .0003"-.0005"	Tin 50 to 70% Lead remainder.
	Rhodium	Metallic and similar to stainless steel in color. Excellent corrosion resistance. Almost as hard as chromium. Very good abrasion resistance. Good solderability. Low contact resistance. Thicker coatings are very brittle. Has high reflectivity.	MIL-R-46085A Type I Type II Class 1 Class 2 Class 3 Class 4 Class 5	.000002" min. .00001" min. .00002" min. .00010" min. .00025" min	Over nickel, silver, gold, or platinum. Over other metals, requires nickel undercoat. Used on silver for tarnish resistance. Application range from electronic to nose cones – wherever wear, corrosion resistance, solderability, and reflectivity are important.
	Zinc	Either a bright or dull finish is acceptable. Bright zinc plating closely resembles bright chromium. However, bright zinc does not have the permanence of surface appearance. Zinc coated steel will not rust even when exposed by scratches because of the galvanic protection of the zinc. On weathering, zinc turns to a drab gray color. Zinc should be deposited directly on the base metal (nickel is permissible undercoat if base metal is a corrosion resisting steel). Parts having a hardness greater that Rc-40 must be given a heat treatment prior to plating. Springs having a hardness over Rc-40 must be given an after plating baking at 375ºF plus or minus 25ºF for 3 hours.	QQ-Z-325C Class 1 Class 2 Class 3 Type I Type II Type III	.0010" .00050" .00020"	The primary use of chromate finishes on zinc is to retard or prevent formation of white corrosion products on zinc surfaces. The primary purpose of phosphate coating on zinc is to provide a paint base. Without supplementary treatments. With supplementary chromate treatment. With supplementary phosphate treatment. Type I and III salt spray requirements: Class 1 = 192 hrs. Class 2 = 96 hrs., Class 3 = 36 hrs.
	Cadmium	Bright silvery white. Supplementary treatments for Type II can be golden, iridescent, amber, black, olive drab. Corrosion resistance is very good, especially with Type II finish. Type II shall show no surface corrosion products after 96 hours (20%) salt spray exposure. Parts with hardness greater than Rc-40 shall be stress-relieved before a cleaning and plating. Parts subject to flexure (springs, etc.) over Rc-40 hardness shall be given a 375ºF plus or minus 25ºF post bake. Salt Spray Test: Type I Class 1 Test Period for White Corrosion Products (Hours)	QQ-P-416C Type I Type II Type III Class 1 Class 2 Class 3	.0005" min. .0003" min. .0002" min	No supplementary treatment. Supplementary chromate treatment. Supplementary phosphate treatment. Type II best for corrosion resistance. Type III is used as a paint base. Excellent for plating stainless steels that are to be used in conjunction with aluminum to prevent galvanic corrosion.
	Copper	Copper in color and matte to a very shiny finish. Good corrosion resistance when used as undercoat. A number of copper processes are available, each designed for a specific purpose. Brightness (to eliminate the need for buffing); High speed (for electroforming); Fine grain (to prevent casehardening); etc.	MIL-C-14550A Class 0 Class 1 Class 2 Class 3 Class 4	Unless otherwise specified. -.001" – .005" .001" .0005" .0002" .0001"	For heat treatment stop-off. For carburizing and decarburizing shield, also plated through printed circuit boards. As an undercoat for nickel and other platings. To prevent basis metal migration into tin (prevents poisoning solderability).
	Nickel	There is a nickel finish for almost any need. Nickel can be deposited soft or hard – dull or bright, depending on process used and conditions employed in plating. Thus, hardness can range from 150-500 Vickers. Can be similar to stainless steel in color, or can be a dull gray or light gray (almost white) color. Corrosion resistance is a function of thickness. Has a low coefficient of thermal expansion – is magnetic. All steel parts having a hardness of Rc-40 or greater require a post bake at 375ºF plus or minus 25ºF for 3 hours.	QQ-N-290A Class 1 Grade A Grade B Grade C Grade D Grade E Grade F Grade G Class 2	Total thickness of copper and nickel. .0016" .0012" .0010" .0008" .0006" .0004" .0002"	NOTE: All steel parts having a tensile strength of 220,000 or greater shall not be nickel plated without specific approval of procuring agency. For corrosion protection. For engineering applications.
	Sulfamate Nickel	The plating conforming to this specification is intended to facilitate the formation of a seal between two metallic surfaces. PLATING HARDNESS. Not to exceed 150 Knoop hardness (500 gm. load) after annealing.	MIL-P-27418	Unless otherwise specified. 0.0020" + or - 0.0003"	The nickel plating shall have a columnar crystalline structure before annealing.
	Passivate	A process designed to remove foreign metals from the surface of stainless and corrosion resistant steels and to promote natural tendency of surface to oxidize. Does not change the appearance of the base metal. Process purifies surface and therefore improves corrosion resistance.	MIL-S-5002C Type I Type II Type III Type IV Type V Type VI	No dimensional change.	Low temperature. Medium temperature. High temperature. For steels containing large amounts (0.15%) of sulfur or selenium. Anodic – For high carbon martensitic (440) steels. Low temperature (optional).