High Phosphorus Electroless Nickel Plating

Niplate 500 is a high-phosphorus (10-13% in P) electroless nickel plating. Among electroless nickel platings, Niplate 500 offers the best chemical and corrosion resistance and should be chosen over the other Niplate coatings for food contact applications.

Thanks to its high phosphorus contents, the high-phosphorus electroless nickel plating alloy has an amorphous structure. This property imparts high chemical resistance in respect of highly aggressive agents such as oxidizing acids. The amorphous structure means that the alloy is non-ferromagnetic and thus not attracted by magnetic fields.

Hardening treatments transform the film structure from amorphous to microcrystalline. They increase film hardness up to 1000 HV, but they reduce chemical resistance slightly and make the layer ferromagnetic.

Niplate 500 features very low porosity, even with thin coatings. This allows effective corrosion protection of the substrate material, especially in the case of parts made of iron or aluminium alloys.

Pneumatic solenoid valve bodies with Niplate 500 high phosphorus electroless nickel plating


Thanks to the high chemical resistance and absence of coating porosity, parts treated with Niplate 500 offer high salt spray corrosion resistance and blackening resistance.


Uniform and constant coating thickness over the entire surface, including holes; ideal for precision machined parts with tight tolerances and complex geometries.


All metals commonly used in mechanical engineering practice can be coated: alloys of iron, copper, and aluminium.


Composition and applicable standards

Ni-P alloy, high phosphorus electroless nickel plating
Technical standards
ISO 4527 | NiP(11)
ASTM B733 | Type V
NSF 51 certification
NSF 51 certification – Food equipment material.
RoHS compliance
RoHS compliant. No restricted substances present in amounts greater than the maximum tolerated concentrations.
REACH compliance
REACH compliant. No SVHCs present in amounts higher than 0.1% by weight.

Coatable metals

Iron alloysCharacteristics
Carbon steelAdhesion★★★★★
Corrosion resistance★★★★☆
Stainless steelPre-treatmentSand blasting
Corrosion resistance★★★★★
Case hardened steelPre-treatmentSand blasting
Corrosion resistance★★★☆☆
Nitrided steelPre-treatmentSand blasting
Corrosion resistance★★★☆☆
Copper alloysCharacteristics
Brass, Bronze, CopperAdhesion★★★★★
Corrosion resistance★★★★★
Aluminium alloysCharacteristics
Machining alloysAdhesion★★★★☆
Corrosion resistance★★★★☆
Foundry alloysAdhesion★★★★☆
Corrosion resistance★★★☆☆
Titanium alloysCharacteristics
Pure titanium and titanium alloysPre-treatmentSand blasting
Corrosion resistance★★★★★

Coating thickness and aesthetic appearance

Coating thickness
Nominal thickness, as requiredTolerance
3÷50µm±10% (min. ±2µm)
Uniform thickness over the entire external and internal surface
Absence of tip effect typical of galvanic coatings
Aesthetic appearance
Bright stainless steel metallic appearance that reproduces the morphology of the machined part
Option of matt finish (sand blasted, shoot peened, or grit blasted)
Hardening treatments may result in discolouration of the coating:
• 340°C, iridescent blue-red colouring

Tribological properties

The surface hardness of Niplate 500 varies in relation to the hardening heat treatment carried out after deposition of the coating.
Hardness valueHeat treatment
Hydrogen embrittlement relief at 160-180°C for 4h
Hardening at 340°C for 4h
Wear resistance
For applications in which the part is subject to wear, the use of Niplate 600 is recommend in place of Niplate 500. Niplate 500 anyway offers a good level of wear resistance, depending on the heat treatment carried out.
Guideline wear value, TWI-CS10Heat treatment
The lower the number, the higher the performance – ASTM B733 X1 – Taber Abraser wear test – CS 10 abrasive wheels – 1 kg load
20±2 mg / 1000 cycles
Hydrogen embrittlement relief at 160-180°C for 4h
12±2 mg / 1000 cycles
Hardening at 340°C for 4h
Friction coefficient
Dynamic dry friction coefficient value
0.4 ÷ 0.6 depending on the antagonist material

Chemical properties

Corrosion resistance
The corrosion protection of Niplate 500, measured by the salt spray test, depends on the substrate metal, machining and finish of the part, and on the applied coating film thickness.
Guideline corrosion resistance valuesSubstrate material
NSS to ISO 9227 – Thickness 20 μm – corroded surface < 5%
≥1000 hours
≥240 hours
Carbon steel
≥240 hours
Aluminium 6082
Chemical resistance
Excellent chemical and oxidation resistance in highly aggressive saline environments.
Passes the concentrated nitric acid immersion test (RCA nitric acid test: 42 degree Bé concentrated nitric acid, 30 seconds, ambient temperature).
Chemical compatibility
Chemical compatibility values are referred exclusively to the coating and do not define the corrosion protection of the substrate material. The overall performance of the coated part is highly dependent also on the type and quality of the substrate material. The actual environmental resistance must anyway be tested in the field.
Hydrocarbons (e.g. petrol, diesel, mineral oil, toluene)
Alcohol, ketones (e.g. ethanol, methanol, acetone)
Neutral saline solutions (e.g. sodium chloride, magnesium chloride, seawater)
Dilute reducing acids (e.g. citric acid, oxalic acid)
Acid oxidizing agents (e.g. nitric acid)
Concentrated acids (e.g. sulphuric acid, hydrochloric acid)
Dilute bases (e.g. dilute sodium hydroxide)
Base oxidizing agents (e.g. sodium hypochlorite)
Concentrated bases (e.g. concentrated sodium hydroxide)

Physical properties

Easily brazed using RMA, RA acid fluxes
FerromagnetismHeat treatment
Non-ferromagneticHydrogen embrittlement relief at 160-180°C for 4h
FerromagneticHardening at 340°C for 4h
Fusion point, solidus
7.9 g/cm3