Electroless (chemical) Nickel-Phosphorus Plating is the most important catalytic process used in the last two decades. Our nickel-phosphorus caoatings have different content of phosphorus. He have three types of coatings: low phosphorus coatings (2-5% P by weight), medium phosphorus coatings (6-9% P by weight) and high phosphorus coatings (>10.5% P by weight). The processes are automatized and are done in working tanks with capacity of 2000 L.
The plating process is based on a redox reaction where a reducing agent, sodium hypophosphite (NaH2PO2)is oxidized and the nickel ions (Ni2+ are reduced at the surface of the material. The process is called autocatalytic because once the first layer of nickel is plated; this acts as a catalyst for the rest of the process. Consequently there is a lineal ratio between the reaction time and the thickness of the coating.
Some of the most important characteristics of these coatings are the high ware and corrosion resistance, excellent uniformity, great range of thicknesses, excellent mechanical and physical properties, good solderability and superficial lubrication.
The properties of the coatings depend on the phosphorus content. The coatings with low phosphorus content are crystalline and hard, so they have a high ware resistance. On the other hand, the high phosphorus content coatings are amorphous and have a high corrosion resistance. Generally, all the types of coatings have good adherence. Though, the adherence properties depends on some parameters as are the thickness of the layer, phosphorus content, heat treatment and the ductility of the substrate. The nickel-phosphorus coatings are self-lubricating and have a good friction coefficient.
A very important and unique characteristic of the electroless coatings is the uniformity of the layer on the same surface; the electroless coatings emulate perfectly the substrate surface.