Types of Permanent Magnet Materials

At present, the common permanent magnetic materials are ferrite, NdFeB, samarium cobalt, aluminium nickel cobalt, rubber magnetism and so on.
Each of the above magnets has its own characteristics and different application fields. The following are briefly introduced:
Ferrite magnet
Ferrite is a non-metallic magnetic material, also known as magnetic ceramics. We take apart the traditional radio. The horn magnet inside is ferrite. At present, the magnetic energy product of ferrite is only slightly higher than that of 4MGOe. One of the greatest advantages of this material is its low price. At present, it is still widely used in many fields. Ferrites are ceramics. Therefore, the machinability is similar to that of ceramics. Ferrite magnets are molded and sintered. If processing is needed, only simple grinding is needed. Because it is difficult to machine, most ferrite products are simple in shape and large in size tolerance. The square shape product is good and can be ground. Other dimensional tolerances are given as a percentage of nominal size. Because ferrite is widely used and inexpensive, many manufacturers will have ready-made circular rings of conventional shapes and sizes, such as diamonds and other products to choose from. Because ferrite is made of ceramics, there is basically no corrosion problem. The finished product does not need surface treatment or coating such as electroplating.

Permanent Magnet Materials
Rubber coated magnet
Rubber magnet is one of the series of ferrite magnets. It is made of bonded ferrite magnetic powder and synthetic rubber by extrusion, calendering and injection molding. It can be processed into the strip, roll, sheet, block, ring, and various complex shapes. Its magnetic energy product ranges from 0.60 to 1.50 MGOe in the application fields of rubber magnets: refrigerators, message boards, fasteners that fix objects to metal bodies for advertising, and magnetic discs for toys, teaching instruments, switches, and sensors. Mainly used in micro and special motors, refrigerators, disinfection cabinets, kitchen cabinets, toys, stationery, advertising, and other industries.

Samarium cobalt
Samarium-cobalt magnets consist mainly of samarium and cobalt. Samarium cobalt magnets are also the most expensive of several magnets because of the high price of the two materials themselves. The magnetic energy product of samarium-cobalt magnet can reach 30MGOe or even higher at present. In addition, samarium cobalt magnets have high coercivity and high-temperature resistance. They can be used at 350 degrees Celsius, so they can not be replaced in many applications. Samarium cobalt magnet belongs to powder metallurgy products. Generally, according to the size and shape of the finished product, the manufacturer sinters the block blank and then uses the diamond blade to cut into the finished product size. Because samarium cobalt is conductive, it can be processed by wire cutting. In theory, samarium and cobalt can be cut into shapes that can be cut by wire cutting, without considering magnetization and larger size. Samarium cobalt magnet, corrosion resistance is good, generally, do not need to carry out anti-corrosion plating or coating. In addition, the texture of samarium cobalt magnet is very brittle, so it is difficult to process small size or thin-walled products.

The neodymium magnet is a magnet product with wide application and rapid development. Neodymium iron boron has been widely used since its invention, and it has not been more than 20 years. Because of its high magnetic properties and processability, the price is not very high, so the application field expands rapidly. At present, the magnetic energy product of commercialized NdFeB can reach 50MGOe, which is 10 times that of ferrite. NdFeB is also a powder metallurgical product, and its processing method is similar to that of SmCo. At present, the highest working temperature of NdFeB is about 180 degrees Celsius. If it is used in harsh environments, it is generally recommended not to exceed 140 degrees Celsius. NdFeB is very susceptible to corrosion. Therefore, most of the finished products need to be electroplated or coated. Conventional surface treatments include nickel plating, zinc plating, aluminum plating, electrophoresis, etc. If working in a closed environment, phosphating can also be used. Because of the high magnetic properties of NdFeB, NdFeB has been used to replace other magnetic materials on many occasions to reduce the volume of products. If we use ferrite magnets, the size of mobile phones today will not be less than half a brick.
Samarium cobalt magnet and neodymium iron boron magnet have better processing performance. Therefore, the dimension tolerance of the product is much better than that of ferrite. General products, size tolerance can be achieved (+/-) 0.05 mm.

Aluminum-nickel-cobalt magnet has two processes: casting and sintering. AlNiCo magnets have a magnetic energy product of up to 9MGOe, which has the greatest characteristic of high-temperature resistance and working temperature of 550 degrees Celsius. However, Al-Ni-Co is very easy to demagnetize in reverse magnetic field. If you push two poles of Al, Ni, and Co together, the magnetic field of one of the magnets will be withdrawn or reversed. Therefore, it is not suitable to work in the reverse magnetic field (such as magnet rotor). Aluminum, nickel, and cobalt have high hardness. Although they can be ground and cut by wire, they are expensive. Generally supplied products, there are two kinds of ground or non-grinded. Aluminum, nickel, and cobalt are widely used in the sensor field.

Anything You Should Know About NdFeB magnets

1. What are the applications of Nd-Fe-B magnets?

Neodymium permanent magnets are rapidly developing and widely used because of their excellent properties, abundant raw materials, and reasonable prices. It is mainly used in micro-motor, permanent magnet instrument, electronic industry, automobile industry, petrochemical industry, nuclear magnetic resonance device, sensors, Halbach Arrays, audio equipment, magnetic levitation system, the magnetic transmission mechanism, and magnetic therapy equipment.

magnetism neodymium magnet

2. What materials are NdFeB made of?

The main materials of the Nd-Fe-B permanent magnet are rare earth metal Nd (32%), metal element Fe (64%) and non-metal element B (1%) (a small amount of Dy, Tb, Co, Nb, Ga, Al, Cu, etc.). Neodymium ternary permanent magnets are based on Nd2Fe14B compound, whose composition should be similar to that of Nd2Fe14B compound. However, when the composition of Nd2Fe14B is completely proportioned, the magnetic properties of the magnet are very low, even no magnetism. It is only when the content of Nd and B in the actual magnet is more than that of the Nd2Fe14B compound that better permanent magnet performance can be obtained.

3. How long can the magnetic properties of NdFeB last?

Neodymium magnets have high coercivity, and there will be no demagnetization and magnetic changes in the natural environment and general magnetic field conditions. Assuming that the environment is suitable, the magnetic properties of the magnet will not be greatly damaged even after a long time of use. So in practical applications, we often neglect the influence of time factor on magnetic properties.

4. What is the direction of the rare earth magnet?

The direction in which the magnet with anisotropic orientation can obtain the best magnetic properties is called the orientation direction of the magnet. The magnet is divided into:

a. Isotropic magnets: magnets with the same magnetic properties in any direction

b. Anisotropic magnets: The magnetic properties will be different in different directions, and there is a direction, i.e. orientation direction, in which the magnets with the highest magnetic properties are obtained. Sintered NdFeB permanent magnets are anisotropic magnets, so it is necessary to determine the orientation (magnetizing direction) before production.

5. Factors affecting the magnetism of neodymium magnets

Because sintered NdFeB is very sensitive to working temperature, the instantaneous maximum temperature and the continuous maximum temperature of the environment may produce different degrees of demagnetization for magnets, including reversible and irreversible, recoverable and irreversible.

6. What is the working temperature range of neodymium magnets?

Temperature limitation of Nd-Fe-B magnets has led to the development of a series of grades of magnets to meet different operating temperature requirements. Please refer to our performance catalog to compare the operating temperature ranges of different grades of magnets. It is necessary to confirm the maximum operating temperature before selecting neodymium magnets.

Which Magnet is Used for Industrial Purpose

Nd-Fe-B magnetic materials, as the latest development of rare earth permanent magnets, are called “magnetic king” because of their excellent magnetic properties. Fe-B is the best magnet with small volume, lightweight and strong magnetism. Major materials for producing NdFeB high-strength magnets are neodymium, pure iron, ferroboron alloy and other additives.

In the healthcare industry, lots of practice and scientific experiments have proved that high-intensity magnetization of neodymium iron boron magnet can change the surface tension, density, solubility and other physical properties of water, and have a significant impact on chemical properties such as acid and alkali. Magnetized water can increase the activity of enzymes in water and permeability of biofilm, often drinking can strengthen health care. Regulate the human body’s microcirculation system, digestive system, endocrine system, and nerve function, improve human immunity, prevent and treat a variety of diseases.

NdFeB magnetic materials

In the scale removal and anti-scaling industry, the angle and length of water molecular bond are deformed simultaneously after high-intensity magnetization of NdFeB. The hydrogen bond angle is reduced from 105 to 103 degrees, which changes the physical and chemical properties of water.

The activity and solubility of water are greatly improved. Calcium carbonate in water is decomposed into lower and soft calcium bicarbonate during cooking. It is not easy to accumulate on the wall and easy to be taken away by water. In addition, the degree of polymerization of water increases, and the dissolved solid matter becomes finer particles. When the particles are refined, the distance between the two ions is smaller, and it is not easy to coagulate on the wall, thus achieving the effect of scale removal.

Environmental protection and energy saving of neodymium cylinder magnet is becoming an important factor affecting the development of manufacturing industry in various countries, and neodymium is one of the main raw materials for environmental protection and energy saving products. For example, the application of NdFeB in automobiles, compressors, wind turbines and other fields is precisely for the consideration of environmental protection and energy conservation.

NdFeB will be more widely used as a functional material for environmental protection and energy saving. In an era of increasing energy shortage, the conversion of wind energy into electricity will undoubtedly be supported by government policies. Wind power generation is now being implemented on a large scale in Europe. The previous one-megawatt unit used about one ton of NdFeB. Thanks to the rapid growth of the wind power industry, the amount of NdFeB used in wind turbines will also be increased rapidly.

Nd-Fe-B magnetic materials, as the latest development of rare earth permanent magnets, are called “magnetic king” because of their excellent magnetic properties. Nd-Fe-B magnet has the characteristics of small volume, lightweight and strong magnetism. It is the best cost performance magnet so far.

How to store magnet?

1. Powerful magnets should not be close to electronic equipment, otherwise, it will affect the control circuit and use of the electronic equipment.

2. Magnets should not be stored in a humid environment to avoid oxidation, resulting in changes in appearance, physical properties, and magnetic properties.

3. If a sensitive object to a metal object approaches a magnet, it will be rough and red. If the above reaction occurs, please do not touch the strong magnet.

4. Do not close the magnets to floppy disks, hard drives, credit cards, tapes, debit cards, television tubes, etc. If the magnet is close to the magnetic recorder and other devices, it will affect or even destroy the recorded data.