Method for enhancing coercive force of neodymium-iron-boron magnet through evaporation grain boundary diffusion
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A grain boundary diffusion, NdFeB technology, applied in the manufacture of inductors/transformers/magnets, electrical components, circuits, etc., can solve the problems of shallow diffusion depth, residual diffusion sources, and low actual utilization of diffusion sources, and achieve coercivity. Strength-enhancing effect
Active Publication Date: 2019-02-19
ZHEJIANG ZHONGKE MAGNETIC IND
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Problems solved by technology
[0005] The purpose of the present invention is to solve the problem that the diffusion depth of the existing sintered NdFeB magnet grain bounda
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Embodiment 1
[0018] (1) Vacuum pre-sintering of the NdFeB oriented compact with the brand name N45H into a pre-sintered green body with a density of 93% and a size of 6 mm, numbered 1#;
[0019] (2) According to the composition ratio, the alloy composition is Te 80 Cu 20 Weigh the ingredients by atomic percentage, carry out vacuum smelting of the weighed target composition raw materials, and repeatedly smelt the alloy 5 times to obtain an alloy ingot with uniform composition;
[0020] (3) Put the alloy ingot into the tungsten boat in the vacuum chamber of the vacuum coating machine, place the NdFeB pre-sintered billet on the rotating sample stage, and adjust the distance between the sample stage and the tungsten boat to 7cm;
[0021] (4) Use a molecular pump to evacuate the vacuum chamber, when the vacuum degree reaches 10 -4 Pa, ready to start evaporation deposition, set the deposition rate on the PID controller as 10nm / min, and the deposition time as 3h;
[0022] (5) Turn on the tungs...
Embodiment 2
[0029] (1) Vacuum pre-sintering of N38UH NdFeB oriented compact into a pre-sintered body with a density of 92% and a size of 6mm, numbered 3#;
[0030] (2) According to the composition ratio, the alloy composition is Dy 80 Al 10 Cu 10 Weigh the ingredients by atomic percentage, carry out vacuum smelting of the weighed target composition raw materials, and repeatedly smelt the alloy 5 times to obtain an alloy ingot with uniform composition;
[0031] (3) Put the alloy ingot into the tungsten boat in the vacuum chamber of the vacuum coating machine, place the NdFeB pre-sintered billet on the rotating sample stage, and adjust the distance between the sample stage and the tungsten boat to 3cm;
[0032] (4) Use a molecular pump to evacuate the vacuum chamber, when the vacuum degree reaches 10 -4 Pa, ready to start evaporation deposition, set the deposition rate on the PID controller as 20nm / min, and the deposition time as 2h;
[0033] (5) Turn on the tungsten boat heating power ...
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Abstract
The invention discloses a method for enhancing the coercive force of a neodymium-iron-boron magnet through evaporation grain boundary diffusion, and belongs to the technical field of magnetic materials. The method comprises the specific technical steps that a neodymium-iron-boron orientated compact is subjected to vacuum pre-sintering, and a pre-sintered compact is obtained; rare earth and alloy elements are subjected to evaporation deposition to be in a form of ionized atoms/molecules and are diffused into the neodymium-iron-boron pre-sintered compact through pores of the pre-sintered compact, subsequently, the rare earth and alloy elements are densified through microwave sintering, and grain boundary diffusion is generated, so that the grain boundary structure of the magnet is improved,and the coercive force of sintered neodymium-iron-boron is improved. The method has the advantages that the rare earth and alloy elements as a diffusion source are in the form of gas-phase atoms/molecules, compared with a liquid diffusion source, the elements can more uniformly, effectively and deeply permeate into the magnet, and the periphery of the neodymium-iron-boron main phase is coated withthe elements; through testing, the coercive force of the neodymium-iron-boron magnet product obtained through gas-phase grain boundary diffusion can be increased by 30% or above, the diffusion depthcan reach 6 mm, and the neodymium-iron-boron magnet product has no hydrogen or fluorine generated through liquid-phase diffusion.
Description
technical field [0001] The invention relates to the technical field of magnetic materials, in particular to a method for enhancing the coercive force of an NdFeB magnet by gas-phase grain boundary diffusion. Background technique [0002] High-end applications require sintered NdFeB magnets to have both high remanence Br and high intrinsic coercive force Hcj to improve the anti-demagnetization ability of the magnet under the impact of temperature, vibration and reverse current. Through composition optimization, quick-setting ingot casting, hydrogen explosion, orientation pressing, sintering, cold isostatic pressing, and oxygen control techniques, the remanence of sintered NdFeB magnets is close to the theoretical value. However, the ternary Nd-Fe-B The internal coercive force of the permanent magnet is less than 30% of the theoretical value. The intrinsic coercivity of sintered NdFeB magnets is determined by the phase composition and microstructure of the material, including...
Claims
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