High performance NdFeB rare earth permanent magnet material and preparation method thereof

Abstract

A preparation method of a high-performance NdFeB rare earth permanent magnet material: (1) batching; (2) melting and casting; (3) preparing magnetic powder; (4) preparing a magnetic field forming green body; (5) cold isostatic pressing; (6) ) low-pressure sintering, put the cold isostatic pressing green body obtained in step (5) into a low-pressure sintering furnace, and when the vacuum is evacuated to the furnace pressure≤1×10 ‑2 Start to heat up at Pa, when the temperature rises to 900-1000°C and keep it warm for 0.5-1.0h, keep vacuuming during the above-mentioned heating and heat preservation process, stop vacuuming after the heat preservation is over, continue to maintain the temperature in the furnace at 900-1000°C and feed High-purity inert gas until the pressure in the furnace is 0.5-4MPa and heat-preservation and pressure-holding sintering for 5-30 minutes. After sintering, stop heat preservation and pass high-purity inert gas at room temperature to cool to room temperature to obtain a sintered magnet; (7) Two-stage heat treatment. The above method can obtain the NdFeB rare earth permanent magnet material with excellent comprehensive magnetic properties and reduce the cost.

Description

technical field [0001] The invention belongs to the technical field of rare earth permanent magnet materials, and in particular relates to a method for preparing rare earth permanent magnet materials. Background technique [0002] In recent years, sintered NdFeB magnets have been widely used in low-carbon economic fields such as wind power generation, hybrid electric vehicles / pure electric vehicles, and energy-saving home appliances. According to the needs of applications, double high magnetic performance magnets (high energy product (BH ) max and high intrinsic coercive force H cj ) and reducing production costs have become the main goals of development. Therefore, how to obtain high comprehensive magnetic properties of magnets at the lowest cost has become an urgent problem to be solved. The main factors affecting the comprehensive magnetic properties of sintered NdFeB magnets are magnet density, grain size, and intergranular phase distribution. [0003] In order to in...

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Problems solved by technology

Since the pre-sintering is carried out in a vacuum sintering furnace and the holding time is long, the hot-press sintering uses a vacuum hot-press furnace, so the operation is more cumbersome, the cost increases, and the oxidation of the magnet is not easy to control; The pressure exerted by the orientation direction (axial direction) of the pre-sintered magnet blank is very large, so the magnetic powder is prone to slip or rotate, resulting in deformation and damage to the orientation of the magnetic powder. At the same time, the requirements for the hot pressing mold are also high.

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