Why demagnetize and how to demagnetize

Demagnetization is essential

The demagnetization of the sample refers to the situation where both the magnetic intensity H and the magnetic induction intensity B are zero. Sometimes, this situation is also referred to as magnetic neutrality, and the process of demagnetizing the sample is called magnetic neutralization. Due to the fact that measuring hysteresis loop is a process in which the magnetic properties of the sample change with the external magnetic field, if there is magnetism at the beginning of the sample, the hysteresis loop will not start from zero, resulting in irregular hysteresis loop.

Two demagnetization methods

1. Thermal demagnetization is the process of heating a sample above its Curie point and then slowly cooling it to room temperature in the absence of an external field. Although the operation process of this method is complex and may cause structural changes to the sample, it can achieve demagnetization.

The Curie point, also known as the Curie temperature or magnetic modification point, refers to the temperature at which a material can be modified between a ferromagnetic and paramagnetic material, i.e. the phase transition temperature at which a ferromagnetic material changes from the ferromagnetic phase to the paramagnetic phase.

2. Communication demagnetization is the process of applying a low-frequency alternating magnetic field to a sample and uniformly reducing its amplitude from a larger value to zero. AC demagnetization is divided into DC commutation demagnetization and AC demagnetization at power frequency.

The AC demagnetization method under power frequency is widely used now. Due to different detailed operation processes, there may be differences in the speed of changes in the magnetic field or sample magnetic induction. The experiment shows that the uniform descent magnetic induction method is a good demagnetization method

Article source: Transformer silicon steel sheethttp://www.cheungshun.com/