What Is a Therapeutic Magnet?

Powerful magnets are NdFeB magnets . Compared with ferrite magnets, AlNiCo, SmCo, its magnetic properties greatly surpass other kinds of magnets. NdFeB magnets can absorb 640 times its own weight, so NdFeB is often used by people outside the industry Called a powerful magnet .

Strong magnet

Most magnetic materials can be magnetized to saturation in the same direction. This direction is called the "magnetization direction" (orientation direction). Magnets without an orientation direction (also called isotropic magnets) are much weaker than oriented magnets (also called anisotropic magnets).

What is the standard "North and South Pole" industry definition?

The definition of "North Pole" is that the magnet's north pole points to the north pole of the earth after the magnet rotates at will. Similarly, the south pole of the magnet points to the south pole of the earth.

How to identify the north pole of a magnet without marking?

Obviously, it is impossible to distinguish only by eyes. You can use a compass close to the magnet, and a pointer to the north pole of the earth will point to the south pole of the magnet.

How to handle and store magnets safely?

Always be very careful, as the magnets stick to themselves and can pinch your fingers. When the magnets are attracted to each other, the magnet itself may be damaged due to collision (hitting corners or cracks).

Keep magnets away from easily magnetized items such as floppy disks, credit cards, computer monitors, watches, mobile phones, medical equipment, etc.

The magnet should be kept away from the pacemaker.

For larger magnets, plastic or hard paper gaskets should be added between each piece to ensure that the magnets can be easily separated.

The magnet should be stored in a dry, constant temperature environment as much as possible.

How to achieve magnetic isolation?

Only the material that can be attracted to the magnet can cut off the magnetic field, and the thicker the material, the better the magnetic isolation effect.

What is the strongest magnet?

At present, the highest performance magnets are rare earth magnets, and neodymium iron boron is the most powerful magnet among rare earth magnets. But in the environment above 200 , SmCo is the most powerful magnet.

Everyone knows that strong magnets are very magnetic, especially large powerful magnets, which can easily hurt people when used. So how can a strong magnet eliminate magnetism?

The method is very simple. The temperature resistance of the powerful magnet is below 80 degrees. We just need to place the powerful magnet on the fire and bake for a few minutes. After cooling, you place it next to the iron block and find that it has lost magnetism and will no longer suck Can't get up. The reason is that the strong magnets are magnetic because the iron atoms in the strong magnets are regularly arranged. After it was heated, the original arrangement of the iron atoms was disordered, so it lost its original magnetism. We can also use other methods to demagnetize powerful magnets.

Magnets should be called Magnets, English Magnet. Magnets are mainly divided into two categories, one is soft magnetic and the other is permanent magnet;

Soft magnetics include silicon steel sheets and soft magnetic cores; hard magnetics include aluminum nickel cobalt, samarium cobalt, ferrites, and neodymium iron boron. Among them, the most expensive is samarium cobalt steel, and the cheapest is ferrite magnetic steel. The highest performance is NdFeB magnetic steel, but the most stable performance, the best temperature coefficient is aluminum nickel cobalt magnetic steel, users can choose different hard magnetic products according to different needs.

How to define the performance of a magnet?

There are three main performance parameters to determine the performance of the magnet:

Remanent Br: Permanent magnet is magnetized to technical saturation, and after removing the external magnetic field, the remaining Br is called the residual magnetic induction intensity.

Coercive force Hc: reduces the magnetization to a technically saturated permanent magnet B to zero. The required reverse magnetic field strength is called the magnetic coercive force.

Called coercive force.

Magnetic energy product BH: represents the magnetic energy density established by the magnet in the air gap space (the space between the two magnetic poles of the magnet), that is, the static magnetic energy per unit volume of the air gap. Because this energy is equal to the product of Bm and Hm of the magnet, it is called magnetic energy product.

Magnetic field: The space that produces a magnetic effect on a magnetic pole is a magnetic field.

Surface magnetic field: The magnetic induction intensity at a specified position on the surface of a permanent magnet.

How to choose a magnet?

Before deciding which magnet to choose, what role does the magnet need to play?

Main role: moving objects, fixing objects or lifting objects.

The shape of the required magnet: disc shape, ring shape, square shape, tile shape or special shape.

Required magnet size: length, width, height, diameter and tolerance, etc.

Required magnet attraction, expected price and quantity, etc.

The compass was invented based on the nature of the magnet

Precautions for storing strong magnets:

1. Do not place strong magnets close to electronic equipment. If they are close, they will affect electronic equipment and control circuits and affect their use.

2. Do not store the magnet in a humid environment to avoid its oxidation, which will cause changes in appearance, physical characteristics and magnetic properties.

3. People with sensitive reactions to metal objects will feel rough and reddened if they approach the magnet. If the above reaction occurs, do not touch the powerful magnet.

4. Do not place magnets near floppy disks, hard drives, credit cards, tapes, debit cards, TV picture tubes, etc. If you place the magnet close to a magnetic recorder or other device, it will affect or even destroy the recorded data.

1 Guide North

2 Attract small magnetic objects

3 Electromagnet can be used as electromagnetic relay

4.Motor

5 Generator

The value of the reverse magnetic field strength required to reduce the magnetic induction strength to zero when the magnet after saturation magnetization of the strong magnet technology is reversely magnetized is called magnetic coercivity (Hcb). However, the magnetization of the magnet is not zero at this time, but the reverse magnetic field and the magnetization of the magnet cancel each other out. (The external magnetic induction intensity is zero.) At this time, if the external magnetic field is cancelled, the magnet still has a certain magnetic performance. The coercive force of NdFeB is generally above 11000Oe.

A magnet is magnetized by an external magnetic field in a closed circuit environment to technical saturation and then the external magnetic field is cancelled. At this time, the magnetic induction strength exhibited by the magnet is called remanence. It represents the maximum magnetic flux value that a magnet can provide. It can be seen from the demagnetization curve that it corresponds to the case when the air gap is zero, so the magnetic induction strength of the magnet in the actual magnetic circuit is less than the remanence. NdFeB is the highest practical permanent magnetic material with the highest Br found today.

The strength of the reverse magnetic field that a strong magnet needs to reduce the magnetization of the magnet to zero is called the intrinsic coercive force. The intrinsic coercive force is a physical quantity that measures the magnet's resistance to demagnetization. If the external magnetic field is equal to the intrinsic coercive force of the magnet, the magnet's magnetism will be basically eliminated. The Hcj of NdFeB will decrease as the temperature increases, so you should choose a high Hcj grade when you need to work in a high temperature environment.

Our ancestors in the pre-Qin era have accumulated a lot of knowledge in this regard. When exploring iron ore, we often encounter magnetite, that is, magnetite (the main component is ferric oxide). These findings have been recorded long ago. These findings were earliest recorded in several articles in "The Pipe": "There are magnets on the mountain, and gold and copper under it."

Similar records are found in other ancient books such as Shan Hai Jing. Magnets' iron-absorbing properties were discovered early on,

There are many types of magnets, which are generally divided into two categories: permanent magnets and soft magnetics. What we call magnets generally refer to permanent magnets.

There are two main categories of permanent magnets:

The first category is: metal alloy magnets including neodymium iron boron magnets (Nd2Fe14B), samarium cobalt magnets (SmCo), aluminum nickel cobalt magnets (ALNiCO)

The second category is: Ferrite permanent magnets (Ferrite)

1. Neodymium iron boron magnet: It is the magnet with the highest commercial performance found at present. It is known as the magnetic king. It has extremely high magnetic properties and its maximum magnetic energy product (BHmax) is more than 10 times higher than ferrite. Its own machinability is also quite good. The maximum operating temperature is 200 ° C. And its texture is hard, its performance is stable, and it has a very good price-performance ratio, so its application is extremely extensive. But because of its strong chemical activity, its surface coating must be treated. (Such as Zn, Ni plating, electrophoresis, passivation, etc.).

2. Ferrite Magnet: Its main raw materials include BaFe12O19 and SrFe12O19. Manufactured by ceramic technology, the texture is relatively hard and it is a brittle material. Because ferrite magnets have good temperature resistance, low price and moderate performance, they have become the most widely used permanent magnets.

3. Aluminum-nickel-cobalt magnet: an alloy composed of aluminum, nickel, cobalt, iron, and other trace metal elements. The casting process can be processed into different sizes and shapes with good workability. Cast aluminum-nickel-cobalt permanent magnets have the lowest reversible temperature coefficient, and the operating temperature can be as high as 600 ° C or more. AlNiCo permanent magnet products are widely used in various instruments and other applications.

4. SmCo is divided into SmCo5 and Sm2Co17 according to the composition. Its development is limited due to its expensive materials. SmCo, as a rare earth permanent magnet, not only has high magnetic energy product (14-28MGOe), reliable coercive force, and good temperature characteristics. Compared with neodymium iron boron magnets, samarium cobalt magnets are more suitable for working in high temperature environments.

With the development of society, the application of magnets is becoming more and more widespread. From high-tech products to the simplest packaging magnets, the most widely used

Also NdFeB magnets and ferrite magnets. From the history of the development of magnets, people mainly used carbon in the late 19th and early 20th centuries.

Steel, tungsten steel, chrome steel and cobalt steel are used as permanent magnetic materials. At the end of the 1930s, the successful development of AlNiCo magnets led to the large-scale application of magnets.

Becomes possible. In the 1950s, the appearance of barium ferrite magnets not only reduced the cost of permanent magnets, but also expanded the application range of permanent magnet materials to

High-frequency area. By the 1960s, the advent of samarium cobalt permanent magnets opened up a new era for the application of magnets. Dayton, 1967

The university's Strnat et al. Developed a SmCo magnet, marking the advent of the rare earth magnet era. So far, rare earth permanent magnets have gone through the first generation

SmCo5, the second generation of precipitation hardening Sm2Co17, has been developed to the third generation of Nd-Fe-B permanent magnet materials. Ferrite magnets are still the most used at present

Permanent magnet materials, but the output value of neodymium iron boron magnets has greatly surpassed ferrite permanent magnet materials, and the production of neodymium iron boron magnets has developed into a major industry

The magnetic force is arranged as follows: neodymium iron boron magnet, samarium cobalt magnet, aluminum nickel cobalt magnet, and ferrite magnet.

Magnet manufacturing process: NdFeB magnet, samarium cobalt magnet, aluminocobalt magnet, ferrite magnet manufacturing process are also different

The performance of powerful magnets can be divided into N33-N52 according to their different magnetic energy products. Different performances can achieve different magnetic forces. There are various high temperature and temperature resistant materials. For specific classification, you can see this figure.