1. Hysteresis Curve
Hard magnetic material (such as NdFeb strong magnetic) has two significant characteristics. One is that it can be strongly magnetized under the action of external magnetic field, and the other is hysteresis, that is, the hard magnetic material still retains the magnetization state after the removal of the external magnetic field. The following figure shows the relationship between the magnetic induction intensity B and the magnetization field intensity H of the hard magnetic material, which is called hysteresis curve.
2. Demagnetization Curve
When the magnetic field reverses from O gradually to -Hc, the magnetic induction intensity B disappears, indicating that to eliminate remanence, the reverse magnetic field must be applied. Hc is called coercivity, and its size reflects the ability of magnetic materials to maintain remanence. The purple line segment is called the demagnetization curve.
3.Intrinsic Curve and Rectangle/Square Degree
The intrinsic magnetic induction generated by permanent magnet materials after magnetization under the action of external magnetic field is called intrinsic magnetic induction Bi, also known as magnetic polarization intensity J. The curve describing the relationship between intrinsic magnetic induction intensity Bi (J) and magnetic field intensity H is a curve reflecting the intrinsic magnetic properties of permanent magnet materials. It is called intrinsic demagnetization curve, or intrinsic curve for short.When the magnetic polarization intensity J on the intrinsic demagnetization curve is 0, the corresponding magnetic field intensity is called intrinsic coercivity Hcj.
4.Surface Treatment - Phosphating
Sintered ndFeb exposed magnets will oxidize and corrode in the air. When Ndfeb magnets are rotated and stored for too long, and the subsequent surface treatment method is not clear, the phosphating process is generally used to do simple anti-corrosion treatment. The phosphating process of the magnet surface is as follows: oil removal → water washing → pickling → water washing → surface conditioning → phosphating treatment → closed drying. The phosphating process is mainly produced by commercial phosphating liquid. After phosphating, the color of the product is uniform and the surface is clean. Vacuum encapsulation can be used to greatly prolong the storage time. The storage hand end is better than the previous storage method of oil immersion and oil coating.