Process for producing sintered NdFeB permanent magnetic material with high corrosion resistance

Abstract

The invention discloses a process for producing a sintered NdFeB permanent magnetic material with high corrosion resistance, which is characterized by sequentially comprising the following process steps: smelting prepared materials in a smelting furnace; producing the smelt material into a throwing belt or a cast ingot with the thickness of 0.3-0.5 mm; producing the throwing belt or the cast ingot into a powder shape with the granularity of 2.5-3.5 microns through hydrogen decrepitation; allowing the powder to enter a gas stream mill containing oxygen with the concentration of 200-500ppm to make the powder; performing magnetic orientation press molding to the powder in a mould after the powder is made; sintering the magnet pressed into a magnetic block in a vacuum sintering furnace; and performing backfire, mechanical processing, surface processing, and the like to obtain a finished product. The invention has the advantages of adjusting the technical parameters of the throwing belt cast by smelting and reducing the probability of the occurrence of transcrystalline rupture from a source; changing the prior mechanical disruption way of an NdFeB permanent magnetic alloy and reducing the proportion of the transcrystalline rupture through selective absorption of the hydrogen among different phases of the alloy; and intentionally introducing 200-500ppm of micro-oxygen in the powder-making process of the gas stream mill to increase the content of the oxide in the alloy powder with even distribution.

Description

technical field [0001] The invention relates to a production process of a sintered NdFeB permanent magnet material with high corrosion resistance. Background technique [0002] Due to its high magnetic product energy, high coercive force and high operating temperature, NdFeB permanent magnet materials have been widely used in many fields such as electronics, computers, automobiles, machinery, energy, and medical equipment. However, due to the influence of the environment and various conditions during use, the chemical properties of the more active rare earth elements in the magnet will be corroded to varying degrees, which will affect the performance of its magnetic properties, and will seriously cause the entire equipment to be scrapped. Therefore, research and development of permanent magnet materials with low weight loss and high corrosion resistance sintered NdFeB has become a subject, especially for permanent magnet materials used in harsh environments. [0003] The ex...

AI Technical Summary

Problems solved by technology

Therefore, the current production process of NdFeB permanent magnet materials is to avoid the contact between the alloy and oxygen as much as possible, but it is inevitably oxidized, and most of the oxidation occurs on the surface of the magnet, which is extremely uneven for the entire magnet. Yes, unable to play a pinning role

Therefore, the NdFeB permanent magnet material produced by the current process has poor corrosion resistance. Under the environment of PCT temperature of 130 ° C and pressure of 0.27 MPa, the weight loss rate of 240 hours is ≥ 100 mg / cm 2