During the use of the trivalent chromium blue zinc passivation solution, many electroplating factories often encounter the problem of difficulty in stabilizing the pH value, which is also a key factor affecting the quality of the passivation film.
By observing some trivalent chromium blue-white zinc passivation solutions available on the market, it can be noticed that the pH values in their process conditions mostly range from 1.6 to 2.3. Why is this range chosen? Because this is the ideal pH range for forming the trivalent chromium passivation film. If the pH value is too low, the film layer will be thinner and prone to fogging problems; if the pH value is too high, the film layer will become loose and the adhesion will significantly decrease.
However, this pH value range does not provide a good chemical polishing effect for the zinc coating. Therefore, before passivation, bright etching needs to be carried out in a dilute nitric acid solution.
During the passivation process of the trivalent chromium blue zinc white passivation solution, as the zinc coating dissolves, the hydrogen ions in the solution will be consumed, and the pH value will also increase. To lower the pH value, nitric acid needs to be added.
Due to the fact that the previous process of the passivation treatment is nitric acid etching, some electroplating factories will choose not to wash the workpieces with water before entering the passivation tank. Instead, they rely on the nitric acid brought in to maintain the pH value, and thus do not need to add nitric acid themselves.
However, it should be noted that too much of the dilute nitric acid solution should not be added either, as adding too much would result in an overly rapid drop in pH value, which is also undesirable.
The engineering team of Bigely has developed the trivalent chromium blue white zinc passivation solution BZ-215 with a wide pH range. Its pH value can be controlled within the range of 1.8 to 3.0. As a result, the electroplating factory has a larger margin for error when controlling the pH value, and there is no need to worry about the instability of the pH value due to the introduction of excessive nitric acid solution. This helps to improve the production efficiency and the quality of the passivation film layer.
About us
Guangdong Bigely Technology Co., Ltd. ,founded in 2003, is a high-tech enterprise integrating R & D，production, sales and service, specializing in the production of electroplating additives. As a famous electroplating additives source manufacturer in China, our products are widely used to meet the plating needs of different industries and exported to many countries from all over the world. They can meet the environmental protection standard after use, mainly used in automobile parts, sanitary ware, electronic products, hardware, furniture, building accessories and other fields.
If you need our high-quality electroplating additives, please contact us. We can provide you samples for test, and also provide a series of services.
