Common problem

Yellow spots appear after the blue zinc workpiece is passivated. Is this the improper use of the trivalent chromium blue zinc passivation solution?

2022-05-31

    We all know that the trivalent chromium blue zinc passivation workpiece needs to have a good bright blue appearance, but sometimes the appearance of the workpiece will appear yellow spots after passivation, which seriously affects the appearance quality of the workpiece.Is this yellow spot caused by improper use of trivalent chromium blue zinc passivation solution?

    Bigolly Technology made an analysis based on the field experience and the characteristics of the product's trivalent chromium blue zinc passivation solution BZ-212,The phenomenon of yellow spots on the workpiece is not due to improper use of the trivalent chromium blue zinc passivation solution.There are four main reasons:


    1. Material problems of passivation tools.Some workpieces need to use a basket for passivation, but a stainless steel basket cannot be used as a passivation tool during passivation, it will affect the passivation effect of the workpiece, and a plastic basket should be used.

    2. The structure of the workpiece.Some workpieces have blind holes, pits, welding gaps, etc., which are easy to hide water during passivation, resulting in yellow watermarks or spots after the workpiece is baked.During production, the water washing process should be improved according to the structural characteristics of the workpiece, and the residual water should be discharged as much as possible.

    3. The water washing of the workpiece is poor.The workpiece may stick together during the washing process without good washing effect, resulting in yellow watermarks or spots on the surface of the workpiece.During production, the washing should be strengthened, or the washing time of the workpiece should be extended to ensure that the workpiece has a good washing effect.

    4. The workpiece bright dipping is not good.Bright dipping water is easy to become turbid due to a lot of impurities after being used for many times, which will affect the bright dipping effect of the workpiece, especially the cyanide-free alkaline galvanizing process is sensitive to impurities, and it is easy to appear macular phenomenon.During the production process, the bright dipping water should be replaced regularly, and the control of the bright dipping effect of the workpiece should be strengthened to ensure that the workpiece bright dipping is good.

    Therefore, when we find that the blue zinc workpiece appears yellow spots after passivation, it is not that the trivalent chromium blue zinc passivation solution is used improperly, but to check the material structure of the product itself, as well as the bright dipping and water washing process.If you are interested in trivalent chromium blue zinc passivation solution,please contact Bigolly customer service, you can get free samples and detailed technical information!   
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