The salt spray test time after galvanizing surface treatment (usually referred to as hot dip galvanizing or electrogalvanizing) can vary greatly, depending on factors such as the thickness of the coating, the quality of the galvanizing process, the conditions of the salt spray test, and post-plating treatment (such as passivation, sealing or coating).
Generally, the hot-dip galvanizing layer is thicker than the electric galvanizing layer, so it performs better in salt spray tests. Electrogalvanizing may have a greater difference in the results of the salt spray test because the coating is thin and the uniformity will vary depending on the quality of the treatment.
The following are some approximate times for reference galvanized surfaces subjected to salt spray tests:
1. Electrogalvanizing (no additional passivation or sealing treatment) : it can usually withstand 24-36 hours of salt spray test, depending on the thickness and quality of the coating.
2. There is blue and white passivation after electric galvanizing: the salt spray time is not less than 72 hours.
3. Hot dip galvanizing (general coating thickness of 45-85 microns) : it can withstand salt spray testing for hundreds to thousands of hours. This number may be higher after passivation or coating.
4. Hot dip galvanizing and additional anti-corrosion treatment, such as passivation, sealing or high performance coating: this can significantly increase the salt spray resistance time, sometimes more than 5000 hours.
It is important to note that the salt spray test is an accelerated corrosion test, which does not always accurately predict the durability of the material in the actual environment; Therefore, the above time should be used as a guide only. Real-world environmental factors such as temperature fluctuations, UV exposure, mechanical friction, and contaminants can affect the corrosion resistance of galvanized coatings. When deciding the specifications and post-treatment methods of galvanized products, the final use environment and requirements should be considered.
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