Key Techniques for Mass-production of NdFeB Magnets

After adding the right amount of Gd or Ho, the formation of¦Á-Fe phase was inhibited in NdFeB alloy ingots, the growth of Nd2Fe14B column crystals was promoted, the Nd-rich phase was uniformly distributed. The magnetic grains were refined to some extent, the microstructure of sintered NdFeB magnets was fine and uniform, the defects, such as holes, were reduced so that sintered NdFeB magnets became more compact.
Adding Gd or Ho could dramatically increase the intrinsic coercivity, slightly decrease the remanence and energy product, significantly improve the thermal stability and corrosion resistance. Addding Gd or small amount of Ho could greatly improve the squareness of J-H demagnetization curve, but adding excessive Ho could greatly decreaseed the squareness of J-H demagnetization curve.
There was a certain influence on the microstructure, orientation degree, and magnetic properties of sintered NdFeB magnets when a certain amount of Dy2O3 was added. After adding the right amount of Dy2O3, Dy could enter the matrix phase, which enhanced the anisotropy field of the matrix phase, so the intrinsic coercivity was significantly improved, and the squareness of J-H demagnetization curve was greatly improved, but the remanence and energy product were slightly decreased.
With the incresing Dy2O3 amount, the density of sintered NdFeB magnet was decreased, and the orientation degree of magnet was significantly improved with more than 1.2%Dy2O3 additions.With some experimental results obtained earlier, the raw materials and the equipment generally used in domestic industrial production of sintered NdFeB magnets, We produced three kinds of sintered NdFeB magnets-42SH, 38UH and 35EH by optimizing the compositions, improving the techniques of alloy ingots, preparation of alloy powders, magnetic field orientation and molding, and sintering.
After being applied, they met the application requirements of user. At the same time, three high-performance sintered NdFeB magnets did not contain Tb so that they saved production cost and improved the market competitions.

Tags: neodymium magnets Key Techniques,Mass-production,NdFeB Magnets Smco magnets