Elektolessnikkelipinnoitus

Elektrolititön nikkelipinnoitus, often abbreviated as EN plating, is a chemical process used to deposit a uniform layer of nickel-phosphorus alloy onto a substrate. Unlike electroplating, it does not require an external electric current. Instead, the deposition occurs through an autocatalytic chemical reaction. The process involves immersing the object to be plated in a heated aqueous solution containing nickel ions and a reducing agent, typically sodium hypophosphite. The hypophosphite reduces the nickel ions to metallic nickel, which then plates onto the surface of the object. The phosphorus content in the deposit, usually between 4% and 14%, influences the properties of the coating.

The primary advantages of electroless nickel plating include its ability to create a highly uniform coating, even on complex shapes with sharp edges, internal surfaces, and blind holes. This uniformity results in consistent thickness across the entire part, unlike electroplating where thickness can vary. EN coatings offer excellent corrosion resistance, wear resistance, and hardness, which can be further enhanced through heat treatment. The hardness of the deposit increases with higher phosphorus content and can reach up to 1000 Vickers after heat treatment.

Applications for electroless nickel plating are widespread, spanning industries such as automotive, aerospace, electronics, oil and gas, and food processing. It is used to protect components from corrosion and wear, improve lubricity, provide a solderable surface, and enhance the aesthetic appearance of parts. Common applications include engine components, pump shafts, valves, connectors, and molds. The process can be applied to a variety of substrates, including steel, stainless steel, aluminum, copper, and brass.