The rare earth family consists of 15 elements from the lanthanide series, plus scandium and yttrium, which are closely related to the lanthanide series, a total of 17 elements. They are: lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, yttrium. The largest user of metal neodymium is NdFeB permanent magnet material. The advent of NdFeB permanent magnets has injected new vigor and vitality into the high-tech field of rare earths. NdFeB magnets have a high magnetic energy product and are known as the contemporary “king of permanent magnets”. They are widely used in electronics, machinery and other industries due to their excellent performance.
Due to the special atomic structure, the members of the rare earth family are very lively, and all of them have extraordinary skills and boundless magic power.
Combined with other elements, they can form new materials with various categories, ever-changing functions and different uses, and their performance is doubled.
They are called contemporary “industrial monosodium glutamate”. For example: АЦР1 and ЖП207 alloys containing rare earths are used in supersonic aircraft, which can work for a long time below 400 ° C. It is one of the alloys with the best high-temperature performance today, and its durable strength can be increased by 1 to 2 times compared with ordinary aluminum alloys. ; After adding rare earth to the steel, the lateral impact toughness of the thin material is increased by more than 50%, and the corrosion resistance is increased by 60%.
However, only about 300 grams of rare earth is added per ton of steel, and the effect is very significant. In textile dyes, it can increase the dyeing rate, adjust the affinity of dyes and fibers, improve the color fastness, improve the color, appearance quality and softness of the fibers, save dyes, reduce environmental pollution and reduce labor intensity, etc.; rare earth elements It can increase the chlorophyll content of plants, enhance photosynthesis, promote the development of roots and the absorption of nutrients.
It can also promote seed germination and seedling growth, and it also has the ability to enhance crop resistance to disease, cold, and drought; using rare earth promethium as a heat source can provide auxiliary energy for vacuum detection and artificial satellites. Promethium batteries can be used as a power source for missile guidance instruments and clocks. This kind of battery is small in size and can be used continuously for several years.
In today’s world, whether it is aerospace, aviation, military and other high-tech fields, or people’s daily necessities, regardless of industry, agriculture and animal husbandry, or chemistry, biology, and medicine, the application and role of rare earths are almost everywhere. omnipotent.
The chemical formula of NdFeB Magnet is: Nd2Fe14B is composed of metal neodymium, iron, boron and other trace elements.
It is the third generation of rare earth permanent magnet materials developed in the 1980s. It is called NdFeB because of its highest magnetic energy product The “Magnetic King” in magnetic materials. According to different production processes, it can be divided into bonded NdFeB (Bonded NdFeB), sintered NdFeB (Sintered NdFeB), injection molding NdFeB.
The neodymium iron stilt produced by the bonding method has high precision, good magnetic properties, good corrosion resistance, and good temperature stability. The products produced by the sintering method are often hard but relatively brittle, and have high resistance to demagnetization, but the cost is relatively high.
The disadvantage of poor temperature resistance, NdFeB manufactured by injection molding has extremely high precision, and it is easy to make thin-walled rings or thin magnets with complex anisotropic shapes, but the magnetic force is poor.
First of all, according to classical electromagnetic theory, only changing electromagnetic fields can produce radiation; magnetic fields with strong radiation capabilities refer to medium and high-frequency magnetic fields (the frequency is above several thousand or even tens of thousands of hertz), such as electromagnetic cooker, mobile phone, etc. Higher electromagnetic fields, there is electromagnetic radiation. The higher the frequency, the stronger the radiation. Normal AC frequency is enough for 220 Hz. NdFeB produces a static magnetic field, which does not produce electromagnetic radiation.
Secondly, since there is no radiation, what we may worry about is whether the static magnetic field is harmful to the human body.
There are two points to explain:
1. The static magnetic field decays quickly. Generally, the strongest single magnet (magnet residual magnetism 1.4T) is 10cm away from the magnet. The magnetic field is generally less than 0.1T, which is very small.
2. Simply discussing the effect of the static magnetic field on the human body, there is currently no clear conclusion in the scientific community, and even many materials claim that the magnetic field is beneficial to the human body, and there are many magnetic therapy devices. There is no clear scientific conclusion on these.
In short, strong magnets will not produce radiation, and the magnetic field at a certain distance away from the magnet is very small and will not affect it.
NdFeB permanent magnet material is a material with strong magnetism.
All kinds of substances and materials around us have large or small magnetism, which are generally very weak. There are not many substances and materials with strong magnetism. Of the more than one hundred elements in the periodic table, only iron, cobalt, nickel, and gadolinium have strong magnetism at room temperature.
Ferrites are also strongly magnetic at room temperature. The so-called magnetic substance, in layman’s terms, is to use a magnet to attract it, and it can be firmly attracted, and the magnetism is very strong, so they are called strong magnetic substances, or strong magnetic materials. NdFeB is an intermetallic compound composed of neodymium, iron and boron, and is an excellent magnetic material.
After being magnetized, its magnetism is not only very strong, but also can be maintained for a long time, and it can be maintained almost permanently. It is an excellent permanent magnet material.
The basic characteristic parameters of permanent magnet materials are as follows:
1. Remanence Br unit Gauss (Gs)
2. Coercivity Hcb and Hcj, unit Oersted (Oe)
3. Maximum energy product (BH)max
4. Curie temperature TC, unit ℃
5. Maximum operating temperature (temperature coefficient).
NdFeB permanent magnet material is a good material with the strongest magnetism and medium price. At present, barium ferrite and strontium ferrite are the most produced and used: cheap products. Alnico: Dominant in analog gauges.
Samarium Cobalt: Dominant in military supplies and high-end consumer products. Platinum cobalt: mainly used in aircraft black boxes, with few products. NdFeB: It has taken a dominant position in electronic computers and their peripheral equipment, and other applications are becoming more and more extensive. NdFeB material has the strongest magnetism, medium price, and good stability under the protection of the surface coating, so its development trend is the best to expand its application range.
Our general understanding of magnets is mostly the adsorption capacity of magnets. In fact, it is a good choice to make many magnetic switches by using the changes in the performance of magnets before and after the critical temperature.
We know that not all magnetic materials are magnetic at any temperature. Generally, magnetic materials have a critical temperature Tc, above this temperature, due to the violent thermal motion of atoms at high temperature, the arrangement of atomic magnetic moments is disordered. Below this temperature, the atomic magnetic moments are aligned, spontaneous magnetization occurs, and the object becomes ferromagnetic.
Taking advantage of this feature, many control components have been developed. For example, the electric rice cooker we use utilizes the characteristics of the Curie point of magnetic materials. A magnet and a magnetic material with a Curie point of 105 degrees are installed in the bottom center of the electric rice cooker. When the water in the pot dries up, the temperature of the food will rise from 100 degrees. When the temperature reaches about 105 degrees, because the magnetism of the magnetic material absorbed by the magnet disappears, the magnet loses its attraction to it. At this time, the spring between the magnet and the magnetic material will separate them, and at the same time drive the power switch to be cut off. On, stop heating.
By analogy, in the vast automatic control field of modern industry, there are many different temperature control points, and people have developed magnetic materials with different critical temperature types, which bring great convenience to all walks of life.
Xiamen Balin New Material Co., Ltd. is a high-tech enterprise integrating independent research and development, production and sales. It has been committed to the processing of magnetic materials for many years. The materials are excellent.
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