[Alcoa.com] The rapid accumulation of aluminum in the alkaline solution will not only shorten the service life of the alkaline solution, but also have an adverse effect on the alkali corrosion rate and the quality of the alkaline parts. It will also increase environmental pollution and material consumption.
In order to reduce the rapid accumulation of aluminum in the alkaline solution, we must first pay attention to the following aspects:
(1) Carefully and carefully pre-treat alkaline parts. If the surface of the pre-alkali corrosion product is heavily oiled or has other contaminants that cannot be removed by the alkaline solution, the alkali etching time must be prolonged, and the aluminum in the alkaline solution will inevitably increase.
(2) Strictly control the process conditions. High concentration, high temperature, and long-term etching in the alkaline etching solution will inevitably accelerate the corrosion of aluminum, which may cause excessive corrosion and accelerate the accumulation of aluminum.
(3) A variety of auxiliary materials, such as sodium carbonate, sodium phosphate, sodium silicate, sodium metasilicate, and emulsifier, are added to the alkali etching solution based on sodium hydroxide. The addition of these materials can enhance the emulsification, saponification of the alkaline solution, and the ability to remove oil on the surface of the part, as well as increase corrosion inhibition and improve wetting and dispersion. It can be seen from these materials that these materials can both reduce the amount of alkaline corrosion and completely eliminate oil pollution. Therefore, it is not simply considered that alkaline etching is the etching of the aluminum oxide layer with sodium hydroxide. Some units even have only sodium hydroxide as a material in the alkaline solution. This is obviously not correct. According to this process, more aluminum will be eroded and it will be difficult to remove all the oil.
In order to reduce the rapid accumulation of aluminum in the alkaline solution, we must first pay attention to the following aspects:
(1) Carefully and carefully pre-treat alkaline parts. If the surface of the pre-alkali corrosion product is heavily oiled or has other contaminants that cannot be removed by the alkaline solution, the alkali etching time must be prolonged, and the aluminum in the alkaline solution will inevitably increase.
(2) Strictly control the process conditions. High concentration, high temperature, and long-term etching in the alkaline etching solution will inevitably accelerate the corrosion of aluminum, which may cause excessive corrosion and accelerate the accumulation of aluminum.
(3) A variety of auxiliary materials, such as sodium carbonate, sodium phosphate, sodium silicate, sodium metasilicate, and emulsifier, are added to the alkali etching solution based on sodium hydroxide. The addition of these materials can enhance the emulsification, saponification of the alkaline solution, and the ability to remove oil on the surface of the part, as well as increase corrosion inhibition and improve wetting and dispersion. It can be seen from these materials that these materials can both reduce the amount of alkaline corrosion and completely eliminate oil pollution. Therefore, it is not simply considered that alkaline etching is the etching of the aluminum oxide layer with sodium hydroxide. Some units even have only sodium hydroxide as a material in the alkaline solution. This is obviously not correct. According to this process, more aluminum will be eroded and it will be difficult to remove all the oil.