Permanent ferrite magnet manufacturer and supplier in China

Explain magnetization processes and demagnetization curves, and how they maintain magnetism at various temperatures.
Before exploring the magnetization and demagnetization mechanism of permanent ferrite magnets, we need to understand the basic principle of magnetism. Magnetism stems from the spin and orbital motion of electrons inside atoms, which creates tiny loops of electric current, known as magnetic moments. In ferromagnetic materials, these magnetic moments tend to spontaneously arrange themselves into magnetic domains in the absence of an applied magnetic field, making the material appear magnetic as a whole.
Magnetization process
The magnetization process of permanent ferrite magnets, a composite material based on iron oxides and other metal oxides, is complex and fascinating. In the absence of an external magnetic field, the magnetic domains in ferrite materials are randomly distributed, resulting in the material as a whole showing no magnetism. However, when an external magnetic field is applied to the material, the magnetic domains begin to reorient in an attempt to align with the external magnetic field. As the magnetic field strength increases, more and more magnetic domains are rearranged until the domains are aligned with the magnetic field direction, at which point the material reaches a state of saturated magnetization.
The magnetization process can be depicted by the hysteresis loop, which is a curve describing the relationship between the magnetization \(M \) and the magnetic field strength \(H \). For ferromagnetic materials, when \(H \) gradually increases from zero, \(M \) also rises until saturation point is reached. Subsequently, even if the external magnetic field is removed, due to the stable arrangement of magnetic domains, the material still retains a certain residual magnetic \(B_r \), which is the reason why permanent ferrite magnets can maintain magnetism for a long time.
Demagnetization curve
Demagnetization occurs when a material attempts to remove or weaken its magnetic properties. When the external magnetic field gradually decreases from the saturation point until it reverses, the magnetic domains begin to rearrange, but do not immediately return to their initial random state. Instead, the material exhibits hysteresis, in which the magnetization lags behind changes in the strength of the magnetic field. This process forms a closed hysteresis loop, the narrowest part of which is called the demagnetization curve. The demagnetization curve describes the change of the magnetization intensity during the process of decreasing the magnetic field gradually from the saturation magnetization state to zero, and then reverting to the saturation demagnetization state.
Temperature effect
The magnetism of permanent ferrite magnet is not only affected by magnetic field, but also significantly affected by temperature. Ferromagnetic materials have a critical temperature, called the Curie temperature, above which the ferromagnetism of the material disappears and transforms into paramagnetism. This is because high temperatures increase the thermal motion of particles inside the material, disrupting the ordered arrangement of magnetic domains. For permanent ferrite magnets, their Curie temperature is relatively high, and they can maintain magnetism over a wide temperature range, but the magnetic strength will gradually weaken as the temperature increases.
When designing and applying permanent ferrite magnets, the effect of temperature on magnetism must be taken into account to ensure that permanent ferrite magnets can maintain sufficient magnetic properties within the expected operating temperature range. For example, permanent ferrite magnets used in motors and audio equipment must be able to withstand the heat generated during operation without significant demagnetization.
In short, the magnetization and demagnetization process of permanent ferrite magnet is determined by the arrangement and rearrangement of its internal magnetic domains, and temperature is an important external factor affecting this process. Through an in-depth understanding of these principles, we can better utilize the unique properties of permanent ferrite magnets and apply them to a wide range of industrial, scientific and daily life.