Phosphating is a kind of surface treatment technology widely used in metal surface treatment. Corrosion resistance is one of the important quality requirements of the body surface. Phosphating layer plays an important role in enhancing the corrosion resistance of the body after painting. Therefore, phosphating technology is being further researched and developed around the world, and the corrosion resistance of the body is enhanced by phosphating. In addition, in recent years, environmental protection requirements are more and more strict, so it is also strongly required to avoid the slag produced in the process of reduction. In order to meet this requirement, we developed a new phosphating product, namely, the electrolytic phosphating solution. This technology greatly increases the corrosion resistance well after the body is painted and the production of phosphating slag is reduced. This technology has been used in the surface treatment of automobile parts before cationic electrophoresis coating.
Electrolytic phosphating is a surface treatment process, which is to form phosphating film on the metal surface by adding voltage between the metal and the electrode which is scattered in the phosphating bath solution. The process is characterized by electrochemical reaction by electrolysis, namely the formation of phosphating film. We developed this technology to reduce the amount of phosphating slag (environmental protection) and improve the corrosion resistance of the body after painting. The most important point is that the rest of the phosphating tank will not react except for the phosphating film reaction on the surface of metal materials.
In general, the phosphating film is generated after three reaction steps:
1. Dissolution of materials (steel materials)
2. Chemical reaction in phosphating bath (phosphate dehydrogenation, etc.)
3. Phosphate crystallization
Traditional non electrolytic phosphating process can promote the process of these reactions by heating phosphating solution and adding chemical drugs to the phosphating tank (such as neutralizer and oxidant). These operations will affect the whole phosphating tank. Besides the phosphating film reaction, it can avoid causing redundant reaction and lead to the production of phosphating slag. The basic idea of electrolytic phosphating process is to make the reaction in the phosphating bath only be carried out on the surface of the treated material to effectively control the formation of phosphating film. The reaction energy (voltage) can be concentrated on the surface of the treated material, thus preventing the non film forming reaction. This not only can inhibit the production of phosphating slag, but also enhance the corrosion resistance after painting.