Electro less nickel (EN) plating is a chemical reduction process which depends upon the catalytic reduction process of nickel ions in an aqueous Process (containing a chemical reducing agent) and the subsequent deposition of nickel metal without the use of electrical energy. Due to its exceptional corrosion resistance and high hardness, the process finds wide application on items such as valves, pump parts etc., to enhance the life of components exposed to severe conditions of service, particularly in the oil field and marine sector. With correct pretreatment sequence and accurate process control, good adhesion and excellent service performance can be obtained from EN deposited on a multitude of metallic and non-metallic substrates.There are four commonly used methods of applying e-Coating to steel surfaces. These are hot-dip galvanizing, thermal spraying, electroplating and sherardizing.
In the EN plating process, the driving force for the reduction of nickel metal ions and their deposition is supplied by a chemical reducing agent in Process. This driving potential is essentially constant at all points of the surface of the component, provided the agitation is sufficient to ensure a uniform concentration of metal ions and reducing agents. Electro less deposits are therefore very uniform in thickness all over the parts shape and size. This process offers distinct advantages when plating irregularly shaped objects, holes, recesses, internal surfaces, valves or threaded parts. Distinct advantages of EN plating are: Uniformity of the deposits, even on complex shapes.
- Deposits are often less porous and thus provide better barrier corrosion protection to steel substrates, much superior to that of electroplated nickel and hard chrome
- The deposits cause about 1/5th as much hydrogen absorption as electrolytic nickel and about 1/10th as much hard chrome.
- Deposits can be plated with zero or compressive stress.
- Deposits have inherent lubricity and non-galling characteristics, unlike electrolytic nickel.
- Deposits have good wet ability for oils