Some customers asked that in the production process of using zinc-nickel alloy colored passivator, the passivation film of the workpiece appeared black phenomenon, what is the cause of this?
According to the field experience and the characteristics of the product Zn-324 zinc-nickel alloy colored passivator, this phenomenon is generally a problem of the zinc-nickel alloy plating process, mainly for the following three reasons:
1. The concentration of nickel metal additive 51019 in zinc nickel alloy plating solution is too high. 51019 is the nickel ion required to supplement the plating solution, when the concentration of 51019 is too high, the nickel content in the coating will be high, and the nickel content is greater than 15% when the workpiece passivation film is prone to blackening. Therefore, we should pay attention to controlling the content of nickel metal additive 51019 in the process range.
2, the current density of zinc-nickel alloy plating is too large. The high current density leads to the fast deposition rate of nickel ions, so that the content of nickel ions in the zinc-nickel alloy coating is greater than 15%, which will cause the phenomenon of passivation film color blackening. Therefore, we should pay attention to controlling the current density in the normal range when zinc nickel alloy plating.
3, the temperature of electrogalvanized nickel alloy plating solution is too high. High temperature, especially above 35℃, will promote the rapid deposition of nickel ions, resulting in the content of nickel ions in the zinc-nickel alloy coating is greater than 15%, resulting in the passivation film color black. Therefore, we should pay attention to controlling the temperature of the bath in the normal range during production.
Therefore, in the production process of using zinc-nickel alloy colored passivator, the workpiece passivation film blackening is generally not a problem of passivator, and in the zinc-nickel alloy plating process need to pay attention to the above three points, can effectively avoid the workpiece passivation film blackening, reduce the occurrence of failure. If you are interested in zinc-nickel alloy colored passivator, please contact Bigely customer service for free samples and detailed technical information!
