What Is a Ferrite Magnet?

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

Ferrite magnet

Ferrite magnet is a kind of permanent magnet made mainly from SrO or BaO and Fe2O3. With other permanent magnets

Ferrite magnets are sintered permanent magnetic materials and are composed of barium and strontium ferrites. In addition to their strong resistance to demagnetization, they also have the advantage of low cost. Ferrite magnets are hard and brittle and require special machining processes. Because the opposite magnet is oriented in the manufacturing direction, it must be magnetized in the direction taken, and because the same magnet is not oriented, it can be magnetized in any direction, although a slightly stronger magnetic induction is often found on the smallest side of the pressure surface. 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 and speakers to toys and crafts, so they are currently the most widely used permanent magnet materials.

It is produced by powder metallurgy, with low remanence, and low recovery magnetic permeability. Large coercive force and strong anti-demagnetization ability, especially suitable for use as a magnetic circuit structure for dynamic working conditions. The material is hard and brittle and can be used for cutting with diamond tools. The main raw material is oxide, so it is not easy to corrode. Operating temperature: -40 ° C to + 200 ° C.

Ferrite magnets are divided into anisotropy (isotropic) and isotropy (isotropic). Isotropic sintered ferrite permanent magnetic materials have weak magnetic properties, but can be magnetized in different directions of the magnet; anisotropic sintered ferrite permanent magnetic materials have strong magnetic properties, but can only follow the magnet's Magnetizing in a predetermined magnetizing direction.

In the actual production of ferrite magnets, raw materials with good chemical composition may not always 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% of the manganese-zinc-ferrite magnet formula, 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 the fineness of the powder particles is not conducive to subsequent pressing and sintering, the APS value should not be too small. Obviously, when the APS value of iron oxide is too large, during the calcination, because of the large particle size, only the spinel phase diffusion reaction can be performed, and the grain growth process cannot be further performed. This inevitably leads to an increase in the activation energy required during sintering, which is not conducive to the solid phase reaction. ^[1]

The main performance grade parameters of sintered permanent ferrite magnets ^[2]

A ferrite magnet is a ferromagnetic metal oxide. In terms of electrical characteristics, ferrite has a much larger resistivity than metal and alloy magnetic materials, and also has higher dielectric properties. The magnetic properties of ferrites also show high magnetic permeability at high frequencies. Therefore, ferrite has become a non-metallic magnetic material that is widely used in the field of high-frequency weak current. It is a non-metal magnetic material and is a composite oxide (or ferrite) of magnetic ferric oxide and one or more other metal oxides. The magnetic force is usually 800-1000 Gauss, which is often used in speakers, speakers and other equipment. ^[3]

The advantages of NdFeB magnets are high cost performance and good mechanical properties. The disadvantages are that the Curie temperature is low, the temperature characteristics are poor, and it is easy to be powdered and corroded. It must be adjusted by its chemical composition and surface treatment Improvement can meet the requirements of practical applications. NdFeB belongs to the third generation of rare earth permanent magnet materials. It has the characteristics of small size, light weight and strong magnetism. It is currently the best magnet with the best performance-price ratio. The advantages of high energy density have made NdFeB permanent magnet materials widely used in modern industry and electronic technology. In the state of bare magnetism, the magnetic force can reach about 3500 Gauss.