As a Modular Pipe System Manufacturer, share with you.
Three possible reasons for the uneven color of the aluminum oxide film:
(1) The area is too large, the swing in the tank is too large during operation, and the contact, renewal, and exchange of the edge and center with the solution are too different, resulting in inconsistent oxide film color. Prevention method: the amplitude of the workpiece swing during oxidation should be small, and static treatment is also possible, but when the temperature of the solution is too low, map-like mottling is easy to appear, which is unnatural.
(2) During the processing of aluminum-clad parts, part of the aluminum-clad layer is damaged and cut off. The outer layer is high-quality aluminum, and the inner layer is mixed aluminum. The two types of aluminum are quite different, so they appear after oxidation. "Liangqifeng" like spots.
(3) Process operation issues
The alkaline etching treatment is not thorough, and the original oxide film and dirt in some parts cannot be removed;
The surface of the workpiece is still alkaline if there is no light-emitting treatment immediately after alkali etching;
The workpiece has touched foreign objects during the transfer process.
When the color of the film is not uniform, it is necessary to find the cause from many aspects and take targeted measures to solve it.
Aluminum Profiles
The fault is caused by the excessive accumulation of aluminum ions in the alkaline etching solution, and it is difficult to obtain the conductive oxide film after the alkaline etching. After eliminating many factors that are difficult to form the conductive oxide film, consider whether there is too high aluminum ion in the alkaline etching solution Question, the other party said that the alkaline etching solution is very thick. But the alkali corrosion rate is not fast. It is recommended to replace the alkaline etching solution, because the alkaline etching solution will accumulate too much aluminum ions after being used for too long, and it is difficult for aluminum ions to be eluted on the surface of the workpiece, which affects the contact between the surface of the aluminum part and the conductive oxidation solution, thereby affecting the oxide film Formation. If the alkali etching solution is replaced unconditionally at that time, the workpiece after alkali etching can be rinsed in running water immediately after rinsing with hot water, and then light out in concentrated nitric acid containing hydrofluoric acid, and then conduct conductive oxidation treatment after sufficient rinsing. After alkali etching, washing with hot water is effective. After washing and scalding in hot water, quickly leave the hot water and immediately immerse in running water to prevent the formation of conductive oxide film due to oxidation after drying.
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