Hard magnetic material containing rare earths with high coercivity and methods of making this material

02/06/2023

Patent No. 34971 “Hard magnetic material containing rare earths with high coercivity and methods of making this material” was granted by the National Office of Intellectual Property to Prof. Dr. Nguyen Huy Dan and his associates from the Institute of Materials Science, Vietnam Academy of Science and Technology, on February 14, 2023. The patent relates to a method to manufacture a hard magnetic material containing rare earths with high coercive force for application in motors and power generators.

Hard magnetic materials (also known as permanent magnets) are widely used in reality. One of the most widely used hard magnetic materials today is the hard magnetic material containing rare earth (Nd,Dy)-Fe-B. The important properties of this material are its high coercivity and large maximum energy storage. Sintered (Nd,Dy)-Fe-B magnets are the most widely used and most effective (compared to other magnets) in motors and generators. Currently, the motors of electric and hybrid electric vehicles almost exclusively use (Nd,Dy)-Fe-B magnets because they require high starting torque, wide operating speed range, and are electricity economical. Besides, magnets (Nd,Dy)-Fe-B also meet the requirements of compact design and easy processing.

By applying micrometer-sized powder containing Dy (Dy-Nd-Pr-Cu-Al) to the grain boundary of the Nd-Fe-B magnet (using powder metallurgy method), Prof. Dr. Nguyen Huy Dan and his colleagues have fabricated magnets with high coercivity, Hc > 25 kOe, and sufficient maximum energy storage, (BH)max > 30 MGOe. With these parameters, magnets meet the requirements in motors and generators. On the other hand, the cost of the magnet is lowered because the concentration of the heavy rare earth element Dy is reduced by 3-4 times compared to the conventional fabrication method (putting Dy into the crystal lattice of the magnet).

The above invention belongs to the research results of the National Science and Technology project "Research on technology to manufacture sintered (Nd,Dy)-Fe-B magnets with high coercivity, semi-industrial scale for application in motors and generators", code KC.02.11/16-20. The results obtained from the project have created a technology that allows the production of high quality rare earth magnets to replace imported goods, improve competition for businesses, and promote energy saving and environmental protection by using wind power and electric vehicles.

Translated by Phuong Huyen
Link to Vietnamese version