Ferrite Magnets Introduction

Ferrite magnet is a permanent magnet mainly made of SrO or BaO and Fe₂O₃ as raw materials. Compared with other permanent magnets, ferrite magnets are hard and brittle with low magnetic energy. However, it is not easy to demagnetize and not corrode, the production process is simple and the price is low. Therefore, the output of ferrite magnets is the highest in the entire magnet industry and is widely used in industrial production.

Ferrite magnet is a sintered permanent magnet material, which is composed of barium and strontium ferrite. This kind of magnetic material not only has strong anti-demagnetization performance, but also has the advantage of low cost. Ferrite magnets are rigid and brittle and require special machining processes. Because the opposite magnet is oriented along the manufacturing direction, it must be magnetized in the direction taken, while the same-sex magnet can be magnetized in any direction because it is not oriented, although a slightly stronger magnetic induction will be found on the side where the pressure is often the smallest. The magnetic energy product ranges from 1.1MGOe to 4.0MGOe. Due to its low cost, ferrite magnets have a wide range of applications, from motors, speakers to toys and handicrafts, so they are currently the most widely used permanent magnet materials.

Ferrite magnets are further divided into anisotropy (anisotropy) and isotropy (isotropy). The isotropic sintered ferrite permanent magnet material has weak magnetic properties, but it can be magnetized in different directions of the magnet; the anisotropic sintered ferrite permanent magnet material has strong magnetic properties, but it can only be magnetized along the direction of the magnet. Predetermined magnetization direction magnetization.

In the actual production of ferrite magnets, sometimes raw materials with good chemical composition may not be able to obtain ferrite magnets with good performance and microstructure. The reason is the influence of physical properties. The listed physical properties of iron oxide include average particle size APS, specific surface area SSA and bulk density BD. Since iron oxide accounts for about 70% in the formula of manganese-zinc ferrite magnets, its APS value has a great influence on the APS value of ferrite magnet powder. Generally speaking, the APS value of iron oxide is small, and the APS value of ferrite magnet powder is also small, which is beneficial to speed up the chemical reaction. However, considering that too fine powder particles are not conducive to subsequent pressing and easy crystallization during sintering, the APS value should not be too small. Obviously, when the APS value of iron oxide is too large, only the diffusion reaction of the spinel phase can be carried out during pre-calcination due to the large particle size, and the further grain growth process cannot be carried out. This will inevitably lead to an increase in the activation energy required for sintering, which is not conducive to solid-state reactions.

 

What is the role of ferrite?

1. Magnetic shielding, or absorbing electromagnetic waves.

2. Isn't ferrite the highest temperature resistance up to 450 ℃? General ferrite can only reach 200 ℃.

3. It has adsorption effect, but the adsorption force is very small, and a bunch of them are conductive, and they are more used in motors.

 

What is the density of ferrite?

Sintered ferrite: The density is about 4.9 g/cm³.

Injection molded ferrite with a density of about 3.8 g/cm³.

 

Where are ferrite magnets used the most?

Ferrite magnets are undoubtedly used most in various motors. Starter motors for motorcycles and cars, and motors for opening sunroofs. Curtain automatic device, toy motor, etc.

 

How much does it cost to open a ferrite mold?

Our company currently has various sizes of molds such as round, ring, square and tile-shaped ferrite magnets, which can help customers save a lot of mold opening costs.