The workpiece needs to be passivated and dehydrogenated after galvanizing with alkaline zinc plating solution. Do you know why?
Bigolly Technology made an analysis based on the field experience and the characteristics of the product alkaline zinc plating solution BZ-515,Passivation treatment after galvanizing the workpiece can obtain a passivation film that improves the decorative performance and corrosion resistance of the coating.Most galvanizing passivation solutions contain chromic acid components. Due to environmental protection and people's restrictions on chromium components, new chromium-free passivation and trivalent chromium passivation processes are widely used.These passivation processes are not as mature as the chromic acid solution passivation process, so there are still some defects in the corrosion resistance of the film obtained after passivation, such as the low corrosion resistance of the passivation film, The color of the film is uneven, and the surface of the film is prone to failures such as white spots.
The hydrogen embrittlement danger that the workpiece may bring to the material matrix (mainly spring steel, high-strength steel, etc.) during the alkaline galvanizing process is usually carried out after galvanizing.The specific operation is to bake at a certain temperature (about 200°C) for more than 4 hours, so that the hydrogen infiltrated into the material during the electroplating process escapes and avoids the occurrence of hydrogen embrittlement fracture of the material.However, in the process of removing hydrogen, the workpiece may also cause the failure of the galvanized layer, such as blistering of the galvanized layer, uneven color of the passive film, etc.
Therefore, in the production process of using alkaline zinc plating solution, sufficient attention must be paid to the passivation treatment and hydrogen removal treatment after the workpiece is galvanized, which can effectively reduce the occurrence of failures.