First, the reason for the black mark after anodizing aluminum
Aluminum anodizing is the formation of an oxide film on the surface of aluminum parts to improve the hardness and corrosion resistance of the material. However, in the actual operation process, it may be found that some black marks appear on the oxide film, affecting the beauty and durability.
There are many reasons for the black mark after the anodizing of aluminum, which may be improper process, excessive impurities in the oxidation liquid and so on. The main reasons for the formation are as follows:
1. Dust or impurities in the air are brought into the oxidation tank and attached to the surface of the aluminum parts to form black marks.
2. The oxidation liquid in the oxidation tank is used for too long, impurities accumulate at the bottom of the tank, and the oxidation liquid deteriorates or is polluted.
3. Improper proportion of oxidizing liquid, resulting in uneven formation of oxide film, resulting in black marks.
4. When pitting or welding occurs, the oxide film formed by local strong oxidation is too thick, forming a black mark.
The above reasons may cause black marks on aluminum parts.
Second, the black mark treatment method after anodizing aluminum
1. Check the process and operation method: the correct operation method can reduce the generation of black marks. Regularly clean the oxidation tank, replace the oxidation liquid, and pay attention to control the entry of gas and impurities in the tank. At the same time, the filter device is added to reduce the pollution to the oxidation liquid.
2. Use special cleaning agents and equipment: Special cleaning agents and ultrasonic cleaning equipment can be used to remove contaminants on the surface of the oxide film. In addition, trace amounts of chemicals can also be used as dispersants and cleaners in the oxidation solution to help reduce pollutants in the oxidation solution.
3. Repair black mark: It can be repaired by simple polishing or pickling method. For parts with relatively light oxide film, polishing machines can be used for polishing. If the oxide film is relatively thick, it needs to be treated by pickling method. The specific pickling method can be determined according to the acid-base degree of the oxidation solution, generally using dilute acid or alkali lotion.
In short, in order to avoid the appearance of black marks after anodizing aluminum, it is mainly through the correct process and the method of cleaning the oxidation liquid to reduce the influence of impurities on the surface of aluminum parts. In the case of black marks, they can be dealt with by means of repair.
