High-performance neodymium magnets

High-performance neodymium magnets, also known as high-performance neodymium iron boron magnets, have higher magnetic energy product and coercivity compared to ordinary neodymium magnets. Generally, we set the performance standard for high-performance neodymium magnets as the sum of the intrinsic coercivity and the maximum magnetic energy product, which is greater than 60.

Hcj(kOe)+(BH)max(MGOe)>60

Application of high-performance neodymium magnets

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The application fields of high-performance neodymium magnets are very wide,including military industry, renewable energy, information communication, electric vehicles and other fields. Due to their excellent magnetic properties, high-performance neodymium magnets have been rapidly developed and applied, becoming a necessary raw material in these fields.

It is divided according to the demand differences of downstream products. Low end neodymium magnets are mainly used in magnetic adsorption, electric bicycles, luggage buckle, door locks,toys and other fields, while high-performance neodymium magnets are mainly used in high-end motors, advanced loudspeaker equipment, nuclear magnetic resonance instruments, wind power generation, elevator motors and other fields.

High-performance neodymium magnets have high magnetic performance indicators, including high remanence and high coercivity, which can result in higher energy conversion efficiency and lower heat generation. At low speeds, they can produce large torques and have high power coefficients.

At the same time, they can also reduce the size of magnets and motors, thereby reducing the size of the equipment accordingly, facilitating maintenance and repair, and saving other raw materials.

High-performance neodymium magnets have higher magnetic flux and energy product, which can improve the accuracy and sensitivity of motor control. The speed regulation range can be increased to over 1000:1, making the motor start more stable and control more precise.

Compared to ordinary neodymium magnets, high-performance neodymium magnets can further reduce energy consumption by more than 5%, with an average energy-saving efficiency of over 15%. In equipment requiring frequent start-stop and variable speed, such as inverter air conditioners and elevators, the energy-saving effect can reach 25%-30%.

High-performance neodymium magnet market

High-performance neodymium magnets
Neodymium magnet blank just sintered

China has the most complete industrial chain of rare earth permanent magnets in the world and has become the world’s largest exporter of rare earth permanent magnet materials. Since 2011, China’s net exports of neodymium magnets have maintained ad overall growth trend, with the net export volume increasing form 24,700 tons in 2011 to 61,400 tons in 2022, with a compound annual growth rate of 8.63%.

At present, neodymium magnets are experiencing a situation of excess supply at the low end and insufficient supply at the high end. The industry structure of neodymium magnets is clearly differentiated, with most enterprises having small scale and low technical level, and their products mainly have low-to-medium performance, leading to fierce market competition. Only a small number of enterprise have the production capacity of high-performance neodymium magnets.

According to statistics, the global production of rare earth permanent magnet materials in 2022 was about 300,000 tons, of which the production of high-performance neodymium magnets was only 47,000 tons, resulting in a shortage of high-end neodymium magnets in the downstream market and affecting the development of downstream industries.

With the rapid development of high-end manufacturing industries represented by new energy vehicles and industrial robots, the demand for rare earth permanent magnet materials in the global market will gradually increase.

How to manufacture high-performance neodymium magnets

1. Improve the formula of raw materials

Increasing the proportion of neodymium: 

Increasing the content of neodymium can improve the magnetic properties of magnets. When smelting neodymium-iron-boron alloys, using neodymium metal instead of praseodymium-neodymium alloys can greatly increase the saturation magnetization, which can be used to prepare ultra-high remanence magnets.

Adding other elements:

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Dy is the most commonly used additive material.  The anisotropy field of Dy2Fe14B compounds is about 2.14 times higher than that of Nd2Fe14B, so replacing a small amount of Nd with Dy can significantly increase the coercivity of the magnet. In theory, replacing 1% (atomic fraction) of Nd with Dy can increase the intrinsic coercivity of the magnet by 11.4kA/m.

In addition, the addition of elements such as terbium, lanthanum, gallium, copper, and aluminum can all increase the remanence or coercivity of the magnet to varying degrees. In practical production, suitable formulations need to be developed based on customers’ specific product requirements. Some rare earth elements are rare and expensive, which is also the main reason why neodymium magnets have higher performance and higher prices.

2.Production process improvement

Melt spining:

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Melt spinning is a metal forming technique that is typically used to form thin ribbons of metal or alloys with a particular atomic structure.

A typical melt spinning process involves casting molten metal by jetting it onto a rotating wheel or drum, which is cooled internally, usually by water or liquid nitrogen. The molten material rapidly solidifies upon contact with the large, cold surface area of the drum. The rotation of the drum constantly removes the solidified product while exposing new surface area to the molten metal stream, allowing for continuous production.

Compared to traditional manufacturing methods, the neodymium magnets produced by this method have the advantages of small grain size, uniform structure, and high magnetic performance.In addition, this method also has the advantages of high production efficiency and low cost, and is widely used in neodymium magnet production.

Vacuum processing:

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High-performance neodymium magnets 13

Airflow milling is a key step in the manufacturing of neodymium magnets, aiming to obtain uniform particle size and high purity magnetic powder. Traditional powder manufacturing methods are often affected by environmental factors such as oxygen and humidity, resulting in magnetic powder oxidation and agglomeration, which damages the final quality of neodymium magnets.

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The forming stage is the process of compressing magnetic powder into the desired shape, which has a decisive impact on the compactness and mechanical strength of neodymium magnets. In traditional forming processes, due to the difficulty in completely removing air and impurities between magnetic particles, defects such as pores and cracks may exist within the compressed magnet.

After using vacuum processing technology, powdering and pressing in a closed, oxygen-free vacuum environment can effectively prevent these negative effects, ensuring that the magnetic powder is not oxidized and has a more uniform particle size, thereby enhancing the magnetic force and coercivity of neodymium magnets.

The use of additives:

In the raw material milling process, the addition of antioxidants can significantly reduce the oxidation level of the finished magnet. Due to the reduction in oxidation risk, we can also grind the powder to a finer particle size, which is beneficial for improving the refinement of the magnet grain and increasing the coercivity of the magnet. Under the same manufacturing process and composition, the intrinsic coercivity of the magnet with the addition of antioxidants can be increased by about 160kA/m.

In addition, lubricants can be added during the milling process to reduce the friction between magnetic particles, improve the fluidity of the magnetic particles, and increase the orientation degree, thereby improving the magnetic energy product of the magnet.

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