Method for improving coercive force of sintered neodymium-iron-boron magnet

Abstract

The invention discloses a method for improving the coercive force of a sintered neodymium-iron-boron magnet. The method comprises the steps of sequentially plating the surface of the sintered neodymium-iron-boron magnet from inside to outside by adopting multi-target continuous magnetron sputtering to form a heavy rare earth metal film layer and a metal aluminum film layer, and discharging to obtain a semi-finished product; and placing the semi-finished product in a pre-vacuumizing environment to be subjected to heat treatment and then cooling to prepare the high-coercivity sintered neodymium-iron-boron magnet , wherein vacuumizing is continuously conducted in the heat treatment process. According to the method, the dischargeable temperature after magnetron sputtering coating is increased, so that the cooling time is shortened; the subsequent charging operation is simplified; and the method has the advantages of saving energy and improving the production efficiency.

Description

technical field [0001] The invention belongs to the field of rare earth permanent magnet materials, and in particular relates to a method for increasing the coercive force of a sintered NdFeB magnet. Background technique [0002] Sintered NdFeB magnets are the most magnetic materials so far. They are widely used in aerospace, automobile industry, electronic appliances, medical equipment, energy-saving motors, new energy, wind power and other fields. The most promising permanent magnet material. Sintered NdFeB magnets have outstanding advantages such as high magnetic energy product, high coercive force, high energy density, high cost performance and good mechanical properties, and have played an important role in the high-tech field. After more than 30 years of research and development, a reasonable alloy composition and a mature preparation process have been designed, so that the remanence and maximum energy product of the sintered NdFeB magnet reach more than 90% of the th...

AI Technical Summary

Problems solved by technology

[0004] However, the current method of direct magnetron sputtering to deposit heavy rare earth metal film layer for grain boundary diffusion also has certain deficiencies, which are mainly manifested in: (1) During the magnetron sputtering process, the magnet will have a certain degree of temperature rise, In order to prevent the heavy rare earth metal coating on the surface of the magnet from being oxidized, the magnet must be cooled to below 80°C after magnetron sputtering before discharging. In order to cool the coated magnet to below 80°C, it usually takes more than 20 minutes time, which to a large extent restricts the further improvement of the production efficiency of continuous coating equipment; (2) The magnets covered with heavy rare earth film layers must be separated from each other when they are placed in a heat treatment furnace for subsequent heat treatment. Otherwise, the two magnets that are in contact with each other will be stuck, which brings great trouble to the placement of the magnet after coating; (3) the vacuum in the furnace must be sufficiently high (usually better than 1× 10 -2 Pa), otherwise the residual air in the furnace will oxidize the heavy rare earth metal layer covered on the surface of the magnet during the heating process, affecting the diffusion effect

These deficiencies directly affect the further improvement of the production efficiency of continuous magnetron sputtering for grain boundary diffusion of sintered NdFeB magnets

Images