Electroless nickel plating in accordance with MIL-C-26704, AMS-C-26074, ASTM B733, AMS 2404
Electroless nickel-teflon in accordance with AMS 2454
Electroless nickel is more versatile than electrolytic nickel plating. What makes this process so interesting is that it is auto catalytic, meaning no external anodes are used to apply nickel onto the parts being plated. This allows uniform plating all over the part because the plating solution is allowed to move freely over the surface of the product being plated. Electroless nickel has many applications, however, it is mostly used in applications where the geometry of the part will not lend itself to electro deposited nickel.
Electroless nickel is available in low, medium and high phosphorous. While most applications use medium phosphorous, there are some applications that require a differing phosphorous level to improve or decrease a wide range of mechanical properties. When you add in baking to harden the deposit, there are endless applications for this process. This process is typically used in microwave, aerospace, and telecommunications applications.
| Specification | Classification | |
| MIL-C-26074 / AMS-C-26074 | Classes (Post Heat Treatment) | |
| 1 | As plated. No subsequent heat treatment. A bake for hydrogen embrittlement relief is not considered a heat treatment. | |
| 2 | Heat treat to obtain required hardness. May be used on all metals not affected by heating to 500⁰F and above. | |
| 3 | Aluminum alloys non-heat treatable, and beryllium alloys processed to improve adhesion of the nickel deposit. | |
| 4 | Aluminum alloys, heat-treatable, processed to improve adhesion of the nickel deposit. | |
| Grades (Thickness) | ||
| A | 0.0010 inch minimum 0.0010 inch minimum | |
| B | 0.0005 inch minimum | |
| C | 0.0015 inch minimum | |
| AMS 2404 | Classes (Post Heat Treatment) | |
| 1 | Except for hydrogen embrittlement relief, no post plating treatment. | |
| 2 | Thermal treatment at 450⁰F (232⁰C) or above to harden the deposit. | |
| 3 | Thermal treatment at 375⁰F (191⁰C) to improve adhesion for non heat-treatable aluminum alloys and beryllium alloys. | |
| 4 | Thermal treatment at 250⁰F (121⁰C) to improve adhesion for heat-treatable aluminum alloys. | |
| ASTM B733 | Types (Deposit Comp.) | |
| I | No requirement for Phosphorous | |
| II | 1 to 3 % P by weight | |
| III | 2 to 4 % P by weight | |
| IV | 5 to 9 % P by weight | |
| V | 10 and above % P by weight | |
| Service Condition (Thickness) | ||
| SC0 | 0.1 micron (0.000004 inch) Minimum thickness | |
| SC1 | 5 micron (0.0002 inch) Light Service | |
| SC2 | 13 micron (0.0005 inch) Mild Service | |
| SC3 | 25 micron (0.001 inch) Moderate Service | |
| SC4 | 75 micron (0.003 inch) Severe Service | |
| Classes (Post Heat Treatment) | ||
| 1 | As-deposited, no heat treatment. | |
| 2 | Heat treatment at 260 to 400⁰C to produce a minimum hardness of 850 HK100. | |
| 3 | Heat treatment at 180 to 200⁰C for 2 to 4 hours to improve coating adhesion on steel and to provide for hydrogen embrittlement relief. | |
| 4 | Heat treatment at 120 to 130⁰C for at least 1 hour to increase adhesion of heat-treatable (age-hardened) aluminum alloys and carburized steel. | |
| 5 | Heat treatment at 140 to 150⁰C for at least 1 hour to improve coating adhesion for aluminum, non age-hardened aluminum alloys, copper, copper alloys and beryllium copper. | |
| 6 | Heat treatment at 300 to 320⁰C for at least 1 hour to improve coating adhesion for titanium alloys. | |
| AMS 2454 (Electroless Nickel–Teflon) | Nickel-phosphorous-polytetrafluoroethylene (PTFE) co-deposit on metal substrates. The process yields a surface with the engineering properties of nickel and the additional lubricity of Teflon®. As with standard electroless nickel, the deposit occurs via an autocatalytic chemical reaction so that a reliable, repeatable coating of uniform thickness is generated. The appearance of the plated finish is usually dull silver-gray, and can be used as a non-reflective coating for military applications. Electroless nickel/Teflon® can be applied over a variety of substrates including stainless steel, aluminum, copper, brass and others. |
