Electroless Nickel Coating

Electroless nickel, as opposed to other electrolytic coatings, does not require current or anodes. The coating is carried out in a watery solution, containing metallic ions, complexes and stabilizers

Electroless nickel, as opposed to other electrolytic coatings, does not require current or anodes.

The coating is carried out in a watery solution, containing metallic ions, complexes and stabilizers.
A chemical reaction occurs on the surface area, creating a layer of alloy, contains nickel and phosphor.
Since the contact surface between the solution and surface is direct the thickness of the coating is mainly uniform.
A unique characteristic of the electroless nickel allows penetration of the coating into internal parts, even in complex structures engineering-wise.
This uniformity of the electroless coating is extremely hard to get and even cannot be created by any other procedure.
The electroless layer is an alloy containing nickel and phosphor, of which 90% is nickel.
In the electroless nickel coating, high as well as low thickness can be reached, thanks to its uniqueness, so that the upper layer of the coating consists of a catalysator for the continuation of the reaction.
The thickness of the coating can vary from 2 micron up to 30 micron.
Compared to other coatings, electroless nickel is relatively new, yet it is greatly used, mainly in engineered coatings but also in decorative coatings, requiring corrosion resistance (according to the type of electroless)
The procedure in our factory is carried out according to:
AMS-C-26074, or ASTM B733.

The thickness of the coating and the treatments is displayed in the tables below:

AMS-C-26074

Grades:

Grade A  Grade B Grade C 
25 micron minimum 12.5 micron minimum 38 micron minimum

 

Classes:

Class I  Without thermal treatment on ferrous and copper bases
Class II  With thermal treatment on ferrous and copper bases
Class III  With thermal treatment on aluminum and copper beryllium alloys that are not react to thermal treatment
Class IV With thermal treatment on aluminum and copper alloys that react to thermal treatment

 

ASTM B733

Type of phosphorus containment:

Type I No demand for phosphorus 0% phosphorus
Type II 1%-3% phosphorus Low phosphorus
Type III  2%-4% phosphorus Low phosphorus
Type IV 5%-9% phosphorus Medium phosphorus
Type V  10% and above High phosphorus

 

Minimum thickness required:

Service Condition 0 0.1 micron minimum
Service Condition 1 5 micron minimum
Service Condition 2  13 micron minimum
Service Condition 3 25 micron minimum
Service Condition 4 75 micron minimum

 

Thermal treatments:

Class 1  Without thermal treatment     
Class 2 







 
Thermal treatment for hardness enlargement 







 
Type I




Type II
Type III
Type IV
Type V 
260°c 20 hours or
285°c 16 hours or
320°c 8 hours or
400°c 1 hour

350°c-380°c 1 hour
360°c-390°c 1 hour
365°c-400°c 1 hour
375°c-400°c 1 hour
Class 3  Thermal treatment for adhesion improvement on ferrous alloys   180°c-200°c 2-4 hours
Class 4 Thermal treatment for adhesion improvement on ferrous alloys containing carbon and hardened aluminum   120°c-130°c 1-6 hours
Class 5 Thermal treatment for adhesion improvement on beryllium and aluminum alloys   140°c-150°c 1-2 hours
Class 6  Thermal treatment for adhesion improvement on titanium   300°c-320°c 1-4 hours


In cases where there is demand for different qualities than the above,
a different type of electroless nickel (with a lower or a higher quantity of phosphorus)
can be ordered. The electroless nickel coating is not poisonous and authorized by
the American Health Organization as the best coating for cutlery.

 


 


The Electroless nickel processes in our plant are medium phosphorus electroless nickel and high phosphorus electroless nickel, where the main characters of this processes are:

 

Type of -Nickel phosphor Medium phosphorus 6-8%{w} High phosphorus 8-12%{w}
Appearance Very shiny  Shiny
Melting point 680°c -960°c 880°c
Electrical resistance 75microohm cm 100 microohm cm
Hardness


 
550 Vickers before thermal treatment {about 50RC}
950 Vickers after thermal treatment {about 70RC}
530 Vickers before thermal treatment {about 48RC}
1050 Vickers after thermal treatment {about 80RC}
Corrosive resistance 100 hours in a salt spray chamber according to ASTM B117 100 hours in a salt spray chamber according to ASTM B117
Magnetic qualities Slightly magnetic Non magnetic


In cases where there is demand for different qualities than the above,
a different type of electroless nickel (with a lower or a higher quantity of phosphorus)
can be ordered.