Electroless Nickel is generally used as a functional coating rather than decorative. Primary uses for Electroless Nickel would be for Corrosion Resistance, Wear Resistance, Hardness, Lubricity, Uniformity of Deposit, and for the Non-Magnetic properties of high phosphorous alloys.
Unlike electroplating where electrical current is used, Electroless Nickel is plated autocatalytically. Deposition occurs in an aqueous soluton containing metal ions along with reducing and complexing agents. Chemical reactions on the surface of the work piece cause the deposition of the nickel alloy. Since there’s no electricity involved and all surfaces are in solution for the same amount of time, the deposit thickness is very uniform. Plating internal surfaces, recessed cavities, etc. becomes a reality with Electroless Nickel. Uniformity and internal coverage are many times not possible with electrolytic nickel deposits.
Specific callouts for Electroless Nickel are most often Mil-C-26074, ASTM B733, and AMS 2404