3.Principle and Process Flow of Phosphating
The phosphating process of the magnet surface is as follows: oil removal → water washing → pickling → water washing → surface conditioning → phosphating treatment → closed drying.
Oil removal pickling is the same as electroplating pretreatment. Surface adjustment is a special surface treatment for the surface of NdFeB magnet to adapt to phosphating film. The surface adjustment of NdFeB magnet is generally soaked in weak acid to improve the alloy components on the surface of the magnet, so as to achieve the purpose of generating phosphating film.
The phosphating process is mainly produced by commercial phosphating liquid. Commercial phosphating liquid is divided into zinc, iron, manganese, binary, ternary, multiple and other varieties. Each system has its own advantages and disadvantages. Therefore, in the production and application of NdFeB phosphating, the magnet manufacturers will use their own suitable supply varieties due to the different purchase price and use effect. Some NdFeB products require galvanized phosphating. Galvanized phosphating should be made of zinc series phosphating liquid or zinc containing multiple phosphating liquid.
Phosphating process is divided into high temperature, medium temperature, normal temperature three types. High temperature process generally thick film, phosphating film density is high, thickness is large; Normal temperature process generally thin film layer; The medium temperature process is somewhere in between. Magnetic material manufacturers mostly use normal temperature process, but normal temperature process also needs temperature control to ensure stable temperature (15℃-35℃).
4.Rust Problem After Phosphating
Some people say that the magnetic material after phosphating or rust phenomenon, there are many reasons for this phenomenon, such as: phosphating pool phosphating agent concentration is not enough, resulting in phosphating film is too thin or loose, can not be a good isolation of air; After phosphating, the water is not clean, or the acid of the washing pool is too high, resulting in acid residues on the magnetic material, acid damage phosphating film resulting in rust; In addition, should also check whether the removal of oil is thorough, the removal of oil is not clean will also affect the phosphating effect.
In order to ensure the phosphating effect, special attention should be paid to the composition ratio of phosphating liquid in the process of phosphating to ensure the appropriate temperature; Phosphating time is controlled in 10-15 minutes; The use of hanging or reduce the load, to ensure that there is a certain gap between the magnetic materials, can be fully phosphating.
