稀土永磁及其应用Rare earth permanent magnet and its application
分类Catalog：行业新闻
发布时间Time：2021.08.23
作者：易赞磁业Author:EZC Magnetic
一、稀土永磁材料
稀土永磁材料是将钐、钕混合稀土金属与过渡金属（如钴、铁等）组成的合金，用粉末冶金方法压型烧结，经磁场充磁后制得的一种磁性材料。
稀土永磁分钐钴（SmCo）永磁体和钕铁硼（NdFeB）系永磁体，其中SmCo磁体的磁能积在15～30MGOe之间，NdFeB系永磁体的磁能积在27～50MGOe之间，被称为“永磁王”，是目前磁性最高的永磁材料。钐钴永磁体，尽管其磁性能优异，但含有储量稀少的稀土金属钐和稀缺、昂贵的战略金属钴，因此，它的发展受到了很大限制。我国稀土永磁行业的发展始于60年代末，当时的主导产品是钐-钴永磁，目前钐-钴永磁体世界销售量为630吨，我国为90.5吨（包括SmCo磁粉），主要用于军工技术。
随着计算机、通讯等产业的发展，稀土永磁特别是NdFeB永磁产业得到了飞速发展。
稀土永磁材料是现在已知的综合性能最高的一种永磁材料，它比十九世纪使用的磁钢的磁性能高100多倍，比铁氧体、铝镍钴性能优越得多，比昂贵的铂钴合金的磁性能还高一倍。由于稀土永磁材料的使用，不仅促进了永磁器件向小型化发展，提高了产品的性能，而且促使某些特殊器件的产生，所以稀土永磁材料一出现，立即引起各国的极大重视，发展极为迅速。我国研制生产的各种稀土永磁材料的性能已接近或达到国际先进水平
现在稀土永磁材料已成为电子技术通讯中的重要材料，用在人造卫星，雷达等方面的行波管、环行器中以及微型电机、微型录音机、航空仪器、电子手表、地震仪和其它一些电子仪器上。目前稀土永磁应用已渗透到汽车、家用电器、电子仪表、核磁共振成像仪、音响设备、微特电机、移动电话等方面。在医疗方面，运用稀土永磁材料进行“磁穴疗法”，使得疗效大为提高，从而促进了“磁穴疗法”的迅速推广。在应用稀土的各个领域中，稀土永磁材料是发展速度最快的一个。它不仅给稀土产业的发展带来巨大的推动力，也对许多相关产业产生相当深远的影响。
二、稀土永磁材料分类
1．稀土钴永磁材料，包括稀土钴（1-5型）永磁材料SmCo5和稀土钴（2-17型）永磁材料Sm2Co17两大类。
2．稀土钕永磁材料，NdFeB永磁材料。
3．稀土铁氮（RE-Fe-N系）或稀土铁碳（RE-Fe-C系）永磁材料。
三、稀土永磁材料制备工艺分类
1．粉末冶金烧结工艺制备的烧结磁体；
2．还原扩散制粉或氢碎处理粉末及粉末冶金烧结工艺制备的烧结磁体；
3．快速凝固制粉或氢碎制粉（HDDR），粉末模压粘结工艺制备的粘结磁体；
4．快速凝固制粉或氢碎（HDDR）粉末的注射工艺制备的注射磁体；
5．快速凝固制粉或氢碎（HDDR）粉末的热压法制备的热压磁体；
6．用热压磁体再进行热变形压工艺制备的各向异性热变形压磁体；
7．将热变形压磁体磨制成粉，再采用模压或注射等方法制备成各向异性粘结磁体。
四、稀土永磁材料的主要应用
永磁体最基本的作用是在某一特定的空间产生一恒定的磁场，维持此磁场并不需要任何外部电源。标志永磁材料好坏的参数有许多，最重要的是最大磁能积(BH)max，磁能积越大，材料每单位体积所产生外磁场的能量就越大。目前商品NdFeB永磁材料的最大磁能积已达到：50MGOe。由于稀土永磁材料的高磁能积和高矫顽力等优异的特性，已给永磁应用带来革命性的变化，稀土永磁材料主要应用在以下几个方面：
1．机电类
稀土永磁体的出现，意味着电机领域将引起革命性的变化。这是因为稀土永磁体没有激磁损耗，不发热，用它制造的电机优点很多。因稀土永磁电机没有激磁线圈与铁心，磁体体积较原来磁场极所占空间小，没有损耗，不发热，因此为得到同样输出功率整机的体积，重量可减小30%以上，或者同样体积、重量，输出功率大50%以上。
永磁电机，尤其是微电机，每年世界产量约几亿台之多，主要用在汽车、办公自动化设备和家用电器中。所使用的多为高性能的铁氧体和稀土永磁体。
今后稀土永磁电机的最大市场之一将是汽车工业。钕铁硼永磁材料性能优异，用于制造电机，可以实现汽车电机“钕铁硼化”。在汽车方面，只有用小马达，才能降低汽车重量，增加舒适感，提高安全性，降低尾气排放，提高汽车的整体性能，目前用量最大的是启动电机。电机是汽车中不可缺少的部件，汽车上电机数量在逐年增加。一般汽车上有8～18台，高级轿车多达40～50台，随着汽车工业的发展，汽车电机的需求是巨大的。高磁能积的稀土永磁体体积小，却能较铁氧体产生大得多的动力，因此提高了电效率。通过使用稀土磁体减少重量和尺寸，可以节约更多的燃料和增加设计的灵活性。
2．稀土永磁材料在医疗中的应用
3．磁选机
一般的磁选机有永磁式和电磁式两种，以前，永磁式磁选机的磁体多用铁氧体。稀土永磁出现后，设计并制造了各种型号和类型的永磁磁选机，尤其是在中高磁场磁选机中，必须用稀土永磁体。
4．计算机及外围设备
在计算机中使用的稀土永磁材料最多的器件是磁盘驱动电机（VCM），另一种是数据输出打印机电机。
5．各种仪表
使用永磁体的仪表种类很多，如磁电式仪表、计数器等。
6．扬声器和耳机
扬声器和耳机是永磁体传统应用领域。扬声器有外磁式和内磁式二种，稀土永磁出现后在同样输出功率与音质下，扬声器被做得非常小，目前稀土永磁扬声器和耳机已应用到高级随身听。
7．微波器件
在微波领域中，微波管、毫波管发生器或放大器需要稳定磁场。稀土永磁体在此中主要起电子运动的聚集作用。
五、稀土永磁材料现状及未来发展趋势
近年来稀土永磁材料在国内的应用发展很快，目前已应用于一般电机、大电机如磁力泵、磁选设备、永磁吊车和家用电器等方面。但与西方国家相比，我国生产的钕铁硼磁体，包括出口，用得最多的是音响器件（中国是全球最大的扬声器生产者，国产钕铁硼有近一半用于制造扬声器），其次是电机和油井除蜡器。而在音圈马达等国外用量最多的领域，我国的应用还很少。其原因在于这两个应用领域所用的磁体，不仅要求磁性能高，均匀性、一致性好，而且要求加工精度高，镀层质量好，国内大多数厂家的产品难于满足上述使用要求。1、 Rare earth permanent magnet material
Rare earth permanent magnet material is a kind of magnetic material made of the alloy composed of samarium and neodymium mixed rare earth metals and transition metals (such as cobalt, iron, etc.), which is pressed and sintered by powder metallurgy and magnetized by magnetic field.
Rare earth permanent magnets are divided into samarium cobalt (SmCo) permanent magnets and neodymium iron boron (NdFeB) permanent magnets. The magnetic energy product of SmCo magnets is between 15 and 30mgoe, and the magnetic energy product of NdFeB permanent magnets is between 27 and 50mgoe. It is known as the "king of permanent magnets". It is the most magnetic permanent magnet material at present. Although samarium cobalt permanent magnet has excellent magnetic properties, it contains rare earth metal samarium and rare and expensive strategic metal cobalt. Therefore, its development is greatly limited. The development of China's rare earth permanent magnet industry began in the late 1960s. At that time, the leading product was samarium cobalt permanent magnet. At present, the world sales volume of samarium cobalt permanent magnet is 630 tons and that of China is 90.5 tons (including SmCo magnetic powder), which is mainly used in military technology.
With the development of computer, communication and other industries, rare earth permanent magnet, especially NdFeB permanent magnet industry, has developed rapidly.
Rare earth permanent magnet material is a kind of permanent magnet material with the highest comprehensive performance. It has more than 100 times higher magnetic properties than the magnetic steel used in the 19th century, much better properties than ferrite and Al Ni Co, and twice higher magnetic properties than the expensive platinum cobalt alloy. The use of rare earth permanent magnet materials not only promotes the miniaturization of permanent magnet devices, improves the performance of products, but also promotes the emergence of some special devices. Therefore, the emergence of rare earth permanent magnet materials immediately attracted great attention and developed very rapidly. The properties of various rare earth permanent magnet materials developed and produced in China have approached or reached the international advanced level
Now rare earth permanent magnet materials have become important materials in electronic technology and communication. They are used in traveling wave tubes and circulators in satellite and radar, as well as micro motors, micro recorders, aviation instruments, electronic watches, seismometers and other electronic instruments. At present, the application of rare earth permanent magnet has penetrated into automobile, household appliances, electronic instruments, nuclear magnetic resonance imaging instrument, audio equipment, micro special motor, mobile phone and so on. In medical treatment, the use of rare earth permanent magnet materials for "magnetic acupoint therapy" has greatly improved the curative effect, thus promoting the rapid promotion of "magnetic acupoint therapy". Rare earth permanent magnet materials are one of the fastest developing fields in the application of rare earth. It not only brings great impetus to the development of rare earth industry, but also has a far-reaching impact on many related industries.
2、 Classification of rare earth permanent magnet materials
1. Rare earth cobalt permanent magnet materials, including rare earth cobalt (type 1-5) permanent magnet material SmCo5 and rare earth cobalt (type 2-17) permanent magnet material Sm2Co17.
2. Rare earth neodymium permanent magnet material, NdFeB permanent magnet material.
3. Rare earth iron nitrogen (re-fe-n system) or rare earth iron carbon (re-fe-c system) permanent magnet materials.
3、 Preparation process classification of rare earth permanent magnet materials
1. Sintered magnet prepared by powder metallurgy sintering process;
2. Sintered magnets prepared by reduction diffusion powder making or hydrogen crushing powder and powder metallurgy sintering process;
3. Bonding magnet prepared by rapid solidification powder making or hydrogen crushing powder making (HDDR) and powder molding bonding process;
4. Injection magnet prepared by injection process of rapid solidification powder preparation or hydrogen fragmentation (HDDR) powder;
5. Hot pressed magnet prepared by hot pressing method of rapid solidification powder preparation or hydrogen fragmentation (HDDR) powder;
6. The anisotropic hot deformation piezoelectric magnet prepared by hot deformation pressing process with hot pressing magnet;
7. The hot deformed piezoelectric magnet is ground into powder, and then the anisotropic bonded magnet is prepared by molding or injection.
4、 Main applications of rare earth permanent magnet materials
The most basic function of permanent magnet is to generate a constant magnetic field in a specific space. Maintaining this magnetic field does not need any external power supply. There are many parameters to mark the quality of permanent magnet materials. The most important is the maximum magnetic energy product (BH) max. the larger the magnetic energy product, the greater the energy of the external magnetic field generated by the material per unit volume. At present, the maximum magnetic energy product of commercial NdFeB permanent magnet materials has reached 50mgoe. Due to the excellent characteristics of rare earth permanent magnet materials such as high magnetic energy product and high coercivity, it has brought revolutionary changes to the application of permanent magnet. Rare earth permanent magnet materials are mainly used in the following aspects:
1. Electromechanical
The emergence of rare earth permanent magnets means that the field of motor will cause revolutionary changes. This is because the rare earth permanent magnet has no excitation loss and no heating. The motor made of it has many advantages. Because the rare earth permanent magnet motor has no excitation coil and iron core, the magnet volume occupies less space than the original magnetic field pole, has no loss and no heating. Therefore, in order to obtain the volume of the whole machine with the same output power, the weight can be reduced by more than 30%, or the output power can be increased by more than 50% with the same volume and weight.
Permanent magnet motors, especially micro motors, produce hundreds of millions of units in the world every year, mainly used in automobiles, office automation equipment and household appliances. Most of the used are high-performance ferrite and rare earth permanent magnets.
In the future, one of the largest markets for rare earth permanent magnet motors will be the automotive industry. Nd-Fe-B permanent magnet material has excellent performance. It can be used to manufacture motor and realize "Nd-Fe-B" of automobile motor. In terms of automobile, only small motor can reduce the weight of automobile, increase comfort, improve safety, reduce exhaust emission and improve the overall performance of automobile. At present, the largest consumption is starting motor. Motor is an indispensable part of automobile, and the number of motors on automobile is increasing year by year. There are 8 ~ 18 cars in general and 40 ~ 50 high-end cars. With the development of automobile industry, the demand for automobile motors is huge. The rare earth permanent magnet with high magnetic energy product has small volume, but can produce much greater power than ferrite, so the electrical efficiency is improved. By using rare earth magnets to reduce weight and size, more fuel can be saved and design flexibility can be increased.
2. Application of rare earth permanent magnet materials in medical treatment
3. Magnetic separator
There are two types of general magnetic separators: permanent magnet type and electromagnetic type. In the past, the magnets of permanent magnet magnetic separators mostly used ferrite. After the emergence of rare earth permanent magnet, various models and types of permanent magnet Separators have been designed and manufactured, especially in medium and high magnetic field separators, rare earth permanent magnet must be used.
4. Computer and peripheral equipment
The most rare earth permanent magnet used in computers is disk drive motor (VCM), and the other is data output printer motor.
5. Various instruments
There are many kinds of instruments using permanent magnets, such as magnetoelectric instruments, counters, etc.
6. Speakers and headphones
Speakers and earphones are traditional applications of permanent magnets. There are two types of loudspeakers: external magnetic and internal magnetic. After the emergence of rare earth permanent magnet, the loudspeakers are made very small under the same output power and sound quality. At present, rare earth permanent magnet loudspeakers and headphones have been applied to advanced walkman.
7. Microwave devices
In the microwave field, microwave tubes, milliwave tube generators or Amplifiers need to stabilize the magnetic field. Rare earth permanent magnets mainly play the role of aggregation of electron motion.
5、 Present situation and future development trend of rare earth permanent magnet materials
In recent years, the application of rare earth permanent magnet materials in China has developed rapidly. At present, they have been used in general motors and large motors, such as magnetic pumps, magnetic separation equipment, permanent magnet cranes and household appliances. However, compared with western countries, the most widely used NdFeB magnets produced in China, including exports, are audio devices (China is the world's largest speaker producer, and nearly half of domestic NdFeB magnets are used to manufacture speakers), followed by motors and oil well wax removers. However, there are few applications in China in voice coil motor and other fields with the largest consumption abroad. The reason is that the magnets used in these two application fields require not only high magnetic properties, good uniformity and consistency, but also high machining precision and good coating quality. The products of most domestic manufacturers are difficult to meet the above requirements.
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