Metal Colours Limited

Metal Colours Limited

Zinc Nickel Plating

Description:
Zinc-Nickel Plating: One automatic rack plant with a maximum process window of 3.6m x 0.9m x 1.1m. One large automatic barrel process plant with 1.2m cylinder. Both plants are operating an alkaline zinc-nickel process depositing 12-15% nickel.

Benefits: High zinc-nickel alloy provides an excellent level of corrosion protection, especially under arduous thermal conditions and also lessens the process of voluminous white corrosion deposits typical of conventional and low alloy zinc finishes. [top]

Post-Treatment: High nickel-zinc alloy can be post treated with Hexavalent Chrome Free Thick Film iridescent yellow, bright, blue, olive drab or clear passivate as well as a high quality colour fast black finish. Other post-treatments are available including sealants, lacquers and oils for specific requirements such as enhanced corrosion protection and high torque lubricity. [top]

Corrosion Protection: In general, corrosion protection is a function of the thickness of the deposit. The neutral salt spay test is used to assess the performance of a finish on a component. The test assesses the time before the onset of corrosion to the coating itself, the formation of white rust as well as the time before the onset of corrosion to the component substrate material, red rust. The tables below demonstrate some results from an ASTM B117 5% neutral salt spray test applied to a 5µm deposit. [top]

Neutral Salt Spray - hours to red (white) rust
Passivate type Conventional zinc High Nickel Alloy zinc
Clear 100 (6-24) 900 (240)
Iridescent Yellow 150-200 (72-96) 1500+ (1000)
Black 120-150 (72-96) 1500+ (500)
Hexavalent Chrome Free Thick Film 300 1500+
Properties Conventional Zinc Standard Zinc Alloy High Nickel Zinc Alloy
Nickel % Nil 5-8 12-15
Vickers hardness (100g) 90-130 200-250 400-500
Weldability Poor Good Good
Thermal stability Poor Good Excellent

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