Causes of yellowing of electrophoretic aluminum profiles

　　One commonly used method in the production process of aluminum profiles is electrophoretic coating. But sometimes, after electrophoretic coating, aluminum profiles may turn yellow. What is the reason for this? The main reasons for the yellowing of electrophoretic aluminum profiles are as follows:

　　1. Yellowing phenomenon caused by incomplete washing before aluminum profiles

　　The oxide film is honeycomb shaped, and its porous layout determines the residual sulfuric acid in the pores of the oxide film. As is well known, electrophoretic aluminum profiles used for electrophoresis are prone to yellowing if not completely washed. Regarding this yellowing phenomenon, it is generally believed that the acid radicals in the pores of the oxide film react with the electrophoretic paint and cause the electrophoretic paint film to undergo yellowing. In fact, this yellowing is not the yellowing of the paint film, but rather the yellowing of the oxide film.

　　2. Yellowing phenomenon caused by poor conductivity of aluminum profiles during oxidation

　　If the aluminum alloy profile has poor contact with the conductive rod, the resistance at the contact point will increase, and the end of the aluminum profile will heat up, causing the formation of the oxide film to be too fast and accompanied by baking phenomenon, and even presenting the powdering of the oxide film. At this point, the oxide film is somewhat dirty and the color appears yellow. If electrophoretic aluminum profile production is carried out again, it will show a very significant yellowing phenomenon. This yellowing phenomenon is usually only a few in a row, and is mostly present at the ends of electrophoretic aluminum profiles. Therefore, measures should be taken to ensure excellent contact between electrophoretic aluminum profiles and conductive rods.

　　It can be seen that the yellowing of electrophoretic aluminum profiles is mainly due to two reasons. During the processing process, it is important to pay attention to these two points introduced in the article. Only in this way can we ensure that there will be no yellowing and that the quality of the product will not be affected.