Chemical nickel phosphorus

1. Characteristics and properties

Chemical nickel plating is a process for electroless, autocatalytic nickel-phosphorus alloy deposition. The phosphorus content of Metoba can be selected between 7-9% (Mid-Phos) or 10-12% (High-Phos). The deposited layer thicknesses are usually in the range of 0.5-30µm, are RoHS compliant and conditionally ferromagnetic with hardnesses in the range between 500-580 HV 0.1. Electroless nickel layers with a phosphorus content <10% are increasingly ferromagnetic with decreasing phosphorus content, with a content >10% non-magnetic, ferromagnetic properties and hardnesses up to 980 HV 0.1 can be achieved by heat treatment. Nickel-phosphorus coatings offer a low coefficient of friction, are optically bright, semi-glossy, homogeneous and pore-free from 25µm. Furthermore, they resist most organic and inorganic media, with the exception of oxidized acids.

2. Benefits and areas of application

Chemical nickel coatings serve as diffusion barriers, as soldering aids and are primarily used for corrosion and wear protection. For example, stainless steel can be partially replaced by chemically nickel-plated steel.

An important difference to galvanic nickel plating is that the coatings on the coated component are the same thickness everywhere – also on edges, in bores, in cavities and on surfaces.  All these properties mean that chemical nickel is used especially in the field of functional electroplating. The specifications and test methods for autocatalytically deposited nickel-phosphorus alloy coatings are standardized in accordance with DIN EN ISO 4527.

3. Basic material

Workpieces made of steel, stainless steel, aluminium and non-ferrous metals can be reliably protected against corrosion and wear by chemical nickel plating.

4. Required delivery condition

The goods provided must be largely metallically bright. Residual oils or residual impurities must be removable with conventional aqueous alkaline degreasers. Oils containing silicone, alkali/alkaline earth and high-pressure additives must be avoided at all costs.