In the process of using trivalent chromium black zinc passivation solution , wm is prone to problems such as missing coating, gray and flowery coating, poor adhesion of coating and easy to fall off.So what key points should we pay attention to in the production process?
According to the site experience and the characteristics of the trivalent chromium black zinc passivation solution BZ-217, Bigolly Technology has made an analysis. The following six points should be noted during production:
1. The zinc coating of the workpiece shall be controlled at more than 5 μm. Attention shall be paid to ensure that the blackness of the surface of the workpiece after black passivation is uniform and there will be no leakage of the coating.
2. The passivation solution shall be controlled within the normal concentration range.When the concentration of the passivation solution decreases, the passivation film of the workpiece will become gray due to the decrease of brightness.At this time, add new passivation solution properly to make the passivation film of the workpiece black and shiny.
3. The time and temperature of passivation shall be well controlled when the workpiece is passivated.If the passivation time is too short, the passivation film of the workpiece will show rainbow color, while if the passivation time is too long, the passivation film will be dissolved and peeled off, making the zinc coating too thin.When the passivation temperature is too high, the passivation film of the workpiece is black and opaque, and will appear foggy.Therefore, the temperature of passivation solution should not exceed 30 ℃.
4. When passivating, the workpiece should move slowly and should not swing violently, otherwise the salt spray impact may be too strong and the phenomenon of spots may occur;However, the film is relatively loose during static passivation, which will affect the adhesion between the passivation film and the zinc coating.
5. The workpiece can be sealed after passivation. If black zinc passivation solution is used with sealing agent, it can avoid the fading of black passivation film and effectively improve the corrosion resistance of the coating.
6. The baking time and temperature shall be well controlled when the workpiece is aging.If the baking temperature is too low or the time is too short, the passivation film of the workpiece will appear watermarks, and the adhesion of the coating is poor;If the baking temperature is too high or the time is too long, it is easy to make the passivation film yellow and blossoming.
Therefore, we should pay attention to the above six points in the process of using trivalent chromium black zinc passivation solution to ensure that the passivation solution has good stability, so that the workpiece can be passivated to a black shiny appearance and good film quality, and reduce the occurrence of failures.If you are interested in trivalent chrome black zinc passivation solution, please contact Bigolly customer service for free samples and detailed technical information!
If you want to know more about galvanizing, you can check "Electroplating encyclopedia".
