What are the factors that affect the process specifications for black nickel plating？
Author: Marisa
In the instrument, instrumentation, optics, and electronics industries, a considerable number of parts require blackening to eliminate reflection and alter thermal performance, and black nickel plating can meet the process requirements. The most commonly used black nickel process is Zn Ni alloy. At present, black nickel is more commonly used in antique electroplating of high-end hardware components. What are the factors that affect the process specifications for black nickel plating？
1. Nickel sulfate is the main salt in black nickel plating solution, ensuring a certain amount of Ni ion concentration can be obtained. If the Ni ion concentration is too high, it will reduce the proportion of Zn ions in the coating, cause the coating color to turn gray, and even produce metallic nickel color. It will also cause unstable solution and poor dispersion ability; Too low results in a yellow brown coating with no black stripes and poor adhesion.
2. Zinc sulfate is one of the main salts in the plating solution, and the coating appears gray when the concentration of Zn ions is too low; Excessive binding force decreases. According to the production volume, strive to add less frequently.
3. The influence of pH value is too high, which can cause the plating solution to become turbid and the sulfur content of the coating to peel off. Therefore, it is necessary to regularly measure and adjust the pH value of the plating solution during production.
4. The influence of temperature is that the plating solution temperature is too low, the dispersion ability is poor, and the deposition rate is slow; The nickel content in the coating increases due to high temperature, resulting in a light yellow color.
5. The parts need to be powered on before entering the plating tank, and current interruption is not allowed during the plating process. At the same time, the current density should be strictly controlled within the process specifications. If the current density is too high, the coating may become rough or even burnt, which can easily cause brittle peeling. If the current density is too low, the coating will appear in five colors, sometimes yellow brown with stripes.