The role of NdFeB permanent magnet surface protection has three aspects:
1- Improve the corrosion resistance of NdFeB, and use various surface protections to resist corrosion such as humid environments, acids, alkalis, salts, and harmful gases;
2- Thoroughly clean the surface of the magnet, such as removing loose magnetic particles on the surface, etc., to form a smooth surface to prevent loose magnetic particles from affecting the function or destroying the magnetic system;
3-Operation protection, to prevent magnetic particles from falling off during assembly or work.
NdFeB passivation is similar to phosphating. It forms a protective film on the surface of the workpiece through chemical methods on the NdFeB surface to achieve the purpose of anti-corrosion of the workpiece. Surface chemical conversion coating technology is a common method of surface treatment. At present, phosphating technology is mainly used for NdFeB surface chemical conversion coating treatment, mostly ordinary zinc or iron phosphating. The corrosion resistance of the phosphating film itself is poor, and often It does not independently undertake the anticorrosion function but cooperates with electrophoresis, coating, etc. as the outer layer for composite anticorrosion; at the same time, phosphoric acid and phosphate compounds are used in large quantities in the phosphating process, which is prone to phosphorus pollution, causing adverse consequences such as eutrophication of the water body, and production The process environment is not friendly. Compared with the phosphating agent, the passivating agent has simple components, does not contain phosphoric acid and phosphate compounds, and is more environmentally friendly.
NdFeB passivation process is generally: degreasing→water washing→ultrasonic water washing→pickling→water washing→ultrasonic water washing→pure water washing→pure water washing→passivation treatment→pure water washing→pure water washing→dehydration→drying.