Trivalent chromium black zinc passivation process is widely used in the surface passivation treatment of galvanized layer, which aims to improve the corrosion resistance and corrosion resistance of the coating. However, in practical application, we often encounter the situation of unqualified salt spray test. According to the relevant research, as well as combined with the practical application, we can analyze the reasons for the unqualified salt spray of trivalent chromium black zinc passivation from the following aspects.
1. Passivation solution formulation issues
The rationality of the trivalent chromium black zinc passivate formulation directly affects the quality of the passivate film formation. The ratio of the components in the passivate solution has a key role in the denseness and homogeneity of the final formed film. If the formulation is not appropriate, it may lead to an increase in the porosity of the passivate film, which in turn reduces the salt spray resistance.
2. Improper operating process parameters
Process parameters such as temperature, pH, immersion time, drying conditions, etc. affect the structure and properties of passivation films. Passivation films formed at different temperatures and pH values vary significantly in their corrosion resistance. Improper operation may lead to uneven film thickness or insufficient adhesion of the passivated film, thus reducing the corrosion resistance.
3. Surface condition of the substrate
The cleanliness and surface condition of the substrate surface is critical to the formation of the passivation film. The presence of oil, oxides or impurities on the surface will affect the reaction between the passivation solution and the substrate, resulting in an undense passivation film with poor adhesion, which ultimately affects the results of the salt spray test.
4. Aging and contamination of passivation solutions
Passivation solutions may undergo compositional changes or become contaminated during long-term use, resulting in degradation of their performance. Aging or contaminated passivate liquids tend to result in uneven passivate film thickness and reduced salt spray resistance.
Advantages of using BZ-216 passivation solution
Bigely trivalent chromium black zinc passivate BZ-216 has good stability and passivation effect, which improves the pass rate of the passivate film in salt spray test. Its formulation design ensures the long time stability of the passivate and avoids the problems of other passivates that are prone to aging and failure during long term use.
At the same time, BZ-216 also has a greater adaptability to the passivation process parameters, making the operation easier and reducing the influence of human factors on the final passivation effect.
In summary, the reasons for the unqualified salt spray of trivalent chromium black zinc passivation can be attributed to passivate solution formulation problems, improper operating process parameters, poor surface condition of the substrate, and aging and contamination of the passivate solution.
By using a high-performance passivate such as Bigely trivalent chromium black zinc passivate BZ-216, the quality and corrosion resistance of the passivate film can be improved, thus avoiding salt spray failures.
If you are interested in trivalent chromium black zinc passivate, please feel free to contact us.
