Electroless Nickel Plating
GENERAL DESCRIPTION OF THE TREATMENT
The process of high phosphorus electroless nickel plating (Enp1012) assures a coating with
an high resistance to corrosion, wear and friction.This is a chemical deposition obtained through an oxide-reduction without using the electricity.
The standard equipment required for normal galvanic deposits is not necessary and deposition can be obtained on any substrate of any geometry.
DEPOSIT DISTRIBUTION AND CHARACTERISTICS
It is therefore the ideal solution to wear problems, it can cover areas that normally should be not be coated as holes, undercuts and special areas with complex geometries.
The only necessary condition to obtain a constant and homogeneous deposition is to assure an optimal recirculation of the bath solution. This is possible only with a perfect filtration and a special circulation.
It can be used frame or barrel depending on the characteristics of the item and the needs of the customer.
PHYSICAL AND CHEMICAL PROPERTIES
High phosphorus electroless nickel plating (Enp1012) has an hardness, after deposition, of 500-600 HV, similar to the best of hardened steels.
It is possible to increase the hardness of the layer performing an heat treatment to a temperature of 400 ° C for 1 hour or at lower temperatures (min. 280°C) for 8 hours, resulting in approximately 1000 HV,values similar to those reached by chrome plating.
High phosphorus electroless nickel plating (Enp1012) represents the best layer, not only to ensure the necessary resistance to corrosion but also a very high hardness.
This because the High phosphorus electroless nickel plating (Enp1012) has a microscopic amorphous structure and not crystalline one. This feature is owned by the same electrolytic nickel or chromium.
CORROSION BEHAVIOR
Salt spray tests have indicated that electroless nickel plating is superior to the electrolytic nickel deposits of same thickness as regards corrosion resistance. The reason for it is that electroless nickel plating is less porous than electrolytic nickel deposits with equal deposit thickness.Corrosion resistance also depends on the cycle used for the preparation of surfaces (e.g. polished surfaces vs. sand-blasted surfaces).
Corrosion resistance is higher if the plated part is not subjected to annealing. MATERIALS THAT CAN BE COATED
The following materials can be plated after proper preliminary treatments:• Iron
• High alloy steels
• Cast Iron
• Bronze
• Copper and its alloys
• Brass
• Aluminum and its alloys
• Plastic
HEAT TREATMENTS AFTER NICKEL PLATING
In order to improve High phosphorus electroless nickel plating (Enp1012) adhesion, coated item should be subjected to a dehydrogenation treatment as shown in the table below. High phosphorus electroless nickel plating (Enp1012) hardness can be increased by performing heat treatments with temperatures above 280 ° C.
In this case material characteristics must be considered due to the possibility that they could change their mechanical or dimensional properties.
