稀土永磁及其應用Rare earth permanent magnet and its application
分類Catalog：行業(yè)新聞
發(fā)布時間Time：2021.08.23
作者：易贊磁業(yè)Author:EZC Magnetic
一、稀土永磁材料
稀土永磁材料是將釤、釹混合稀土金屬與過渡金屬（如鈷、鐵等）組成的合金，用粉末冶金方法壓型燒結，經磁場充磁后制得的一種磁性材料。
稀土永磁分釤鈷（SmCo）永磁體和釹鐵硼（NdFeB）系永磁體，其中SmCo磁體的磁能積在15～30MGOe之間，NdFeB系永磁體的磁能積在27～50MGOe之間，被稱為“永磁王”，是目前磁性最高的永磁材料。釤鈷永磁體，盡管其磁性能優(yōu)異，但含有儲量稀少的稀土金屬釤和稀缺、昂貴的戰(zhàn)略金屬鈷，因此，它的發(fā)展受到了很大限制。我國稀土永磁行業(yè)的發(fā)展始于60年代末，當時的主導產品是釤-鈷永磁，目前釤-鈷永磁體世界銷售量為630噸，我國為90.5噸（包括SmCo磁粉），主要用于軍工技術。
隨著計算機、通訊等產業(yè)的發(fā)展，稀土永磁特別是NdFeB永磁產業(yè)得到了飛速發(fā)展。
稀土永磁材料是現(xiàn)在已知的綜合性能最高的一種永磁材料，它比十九世紀使用的磁鋼的磁性能高100多倍，比鐵氧體、鋁鎳鈷性能優(yōu)越得多，比昂貴的鉑鈷合金的磁性能還高一倍。由于稀土永磁材料的使用，不僅促進了永磁器件向小型化發(fā)展，提高了產品的性能，而且促使某些特殊器件的產生，所以稀土永磁材料一出現(xiàn)，立即引起各國的極大重視，發(fā)展極為迅速。我國研制生產的各種稀土永磁材料的性能已接近或達到國際先進水平
現(xiàn)在稀土永磁材料已成為電子技術通訊中的重要材料，用在人造衛(wèi)星，雷達等方面的行波管、環(huán)行器中以及微型電機、微型錄音機、航空儀器、電子手表、地震儀和其它一些電子儀器上。目前稀土永磁應用已滲透到汽車、家用電器、電子儀表、核磁共振成像儀、音響設備、微特電機、移動電話等方面。在醫(yī)療方面，運用稀土永磁材料進行“磁穴療法”，使得療效大為提高，從而促進了“磁穴療法”的迅速推廣。在應用稀土的各個領域中，稀土永磁材料是發(fā)展速度最快的一個。它不僅給稀土產業(yè)的發(fā)展帶來巨大的推動力，也對許多相關產業(yè)產生相當深遠的影響。
二、稀土永磁材料分類
1．稀土鈷永磁材料，包括稀土鈷（1-5型）永磁材料SmCo5和稀土鈷（2-17型）永磁材料Sm2Co17兩大類。
2．稀土釹永磁材料，NdFeB永磁材料。
3．稀土鐵氮（RE-Fe-N系）或稀土鐵碳（RE-Fe-C系）永磁材料。
三、稀土永磁材料制備工藝分類
1．粉末冶金燒結工藝制備的燒結磁體；
2．還原擴散制粉或氫碎處理粉末及粉末冶金燒結工藝制備的燒結磁體；
3．快速凝固制粉或氫碎制粉（HDDR），粉末模壓粘結工藝制備的粘結磁體；
4．快速凝固制粉或氫碎（HDDR）粉末的注射工藝制備的注射磁體；
5．快速凝固制粉或氫碎（HDDR）粉末的熱壓法制備的熱壓磁體；
6．用熱壓磁體再進行熱變形壓工藝制備的各向異性熱變形壓磁體；
7．將熱變形壓磁體磨制成粉，再采用模壓或注射等方法制備成各向異性粘結磁體。
四、稀土永磁材料的主要應用
永磁體最基本的作用是在某一特定的空間產生一恒定的磁場，維持此磁場并不需要任何外部電源。標志永磁材料好壞的參數(shù)有許多，最重要的是最大磁能積(BH)max，磁能積越大，材料每單位體積所產生外磁場的能量就越大。目前商品NdFeB永磁材料的最大磁能積已達到：50MGOe。由于稀土永磁材料的高磁能積和高矯頑力等優(yōu)異的特性，已給永磁應用帶來革命性的變化，稀土永磁材料主要應用在以下幾個方面：
1．機電類
稀土永磁體的出現(xiàn)，意味著電機領域將引起革命性的變化。這是因為稀土永磁體沒有激磁損耗，不發(fā)熱，用它制造的電機優(yōu)點很多。因稀土永磁電機沒有激磁線圈與鐵心，磁體體積較原來磁場極所占空間小，沒有損耗，不發(fā)熱，因此為得到同樣輸出功率整機的體積，重量可減小30%以上，或者同樣體積、重量，輸出功率大50%以上。
永磁電機，尤其是微電機，每年世界產量約幾億臺之多，主要用在汽車、辦公自動化設備和家用電器中。所使用的多為高性能的鐵氧體和稀土永磁體。
今后稀土永磁電機的最大市場之一將是汽車工業(yè)。釹鐵硼永磁材料性能優(yōu)異，用于制造電機，可以實現(xiàn)汽車電機“釹鐵硼化”。在汽車方面，只有用小馬達，才能降低汽車重量，增加舒適感，提高安全性，降低尾氣排放，提高汽車的整體性能，目前用量最大的是啟動電機。電機是汽車中不可缺少的部件，汽車上電機數(shù)量在逐年增加。一般汽車上有8～18臺，高級轎車多達40～50臺，隨著汽車工業(yè)的發(fā)展，汽車電機的需求是巨大的。高磁能積的稀土永磁體體積小，卻能較鐵氧體產生大得多的動力，因此提高了電效率。通過使用稀土磁體減少重量和尺寸，可以節(jié)約更多的燃料和增加設計的靈活性。
2．稀土永磁材料在醫(yī)療中的應用
3．磁選機
一般的磁選機有永磁式和電磁式兩種，以前，永磁式磁選機的磁體多用鐵氧體。稀土永磁出現(xiàn)后，設計并制造了各種型號和類型的永磁磁選機，尤其是在中高磁場磁選機中，必須用稀土永磁體。
4．計算機及外圍設備
在計算機中使用的稀土永磁材料最多的器件是磁盤驅動電機（VCM），另一種是數(shù)據(jù)輸出打印機電機。
5．各種儀表
使用永磁體的儀表種類很多，如磁電式儀表、計數(shù)器等。
6．揚聲器和耳機
揚聲器和耳機是永磁體傳統(tǒng)應用領域。揚聲器有外磁式和內磁式二種，稀土永磁出現(xiàn)后在同樣輸出功率與音質下，揚聲器被做得非常小，目前稀土永磁揚聲器和耳機已應用到高級隨身聽。
7．微波器件
在微波領域中，微波管、毫波管發(fā)生器或放大器需要穩(wěn)定磁場。稀土永磁體在此中主要起電子運動的聚集作用。
五、稀土永磁材料現(xiàn)狀及未來發(fā)展趨勢
近年來稀土永磁材料在國內的應用發(fā)展很快，目前已應用于一般電機、大電機如磁力泵、磁選設備、永磁吊車和家用電器等方面。但與西方國家相比，我國生產的釹鐵硼磁體，包括出口，用得最多的是音響器件（中國是全球最大的揚聲器生產者，國產釹鐵硼有近一半用于制造揚聲器），其次是電機和油井除蠟器。而在音圈馬達等國外用量最多的領域，我國的應用還很少。其原因在于這兩個應用領域所用的磁體，不僅要求磁性能高，均勻性、一致性好，而且要求加工精度高，鍍層質量好，國內大多數(shù)廠家的產品難于滿足上述使用要求。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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