Blackening of nickel plated workpieces in air is not usually a normal phenomenon, and may be caused by oxidation or sulfidation of the nickel plated surface. Nickel plating usually has good corrosion and oxidation resistance, but under certain circumstances, such as insufficient quality of plating, presence of contaminants in the environment, high humidity, or poor storage conditions, the surface of nickel plated parts may become discolored or blackened.
Causes of discoloration or blackening may include:
1. Defects in the plating layer: such as not using the right nickel plating brightener, resulting in pores, cracks and other faults in the plating layer, causing the workpiece to come into contact with oxygen or other chemical substances in the air and react.
2. Thin plating: If the nickel layer is thin, it may not provide sufficient protection and may react with airborne chemicals over time.
3. Environmental pollution: If there are pollutants such as sulfides (e.g. hydrogen sulfide gas) in the air, black nickel sulfide can be formed on the surface of nickel.
4. Improper storage: excessive humidity or temperature changes will accelerate the corrosion rate, resulting in blackening of the nickel coating.
To avoid or minimize the blackening of nickel-plated parts in air, the following measures can be considered:
① Ensure quality control of the plated layer during nickel plating, e.g. by using Bigelow Nickel Plating Brightener to avoid porosity and cracks.
② Use appropriate post-treatment methods, such as passivation, to enhance the protection of the nickel layer.
③ Increase the thickness of the coating appropriately to provide better corrosion resistance.
④Store nickel-plated parts should pay attention to environmental control, avoid high humidity and polluted environments, take measures to protect the plated parts such as sealed packaging or desiccant.
⑤ Clean and maintain nickel-plated parts regularly to remove substances that may cause corrosion.
If you have any demands for Nickel Plating Brightener, please feel free to contact us.
