Introduction to rare earth permanent magnets
2021-08-31

Introduction to rare earth permanent magnets


chemical composition

The third-generation rare earth permanent magnet NdFeB is the most powerful permanent magnet in contemporary magnets. Its main raw material is rare earth metal neodymium 29%-32.5%, metallic element iron 63.95-68.65%, non-metallic element boron 1.1-1.2% and dysprosium 0.6-8% niobium 0.3-0.5% aluminum 0.3-0.5% copper 0.05-0.15% and other elements.


Overview

Each type of product is divided into several grades according to the maximum magnetic energy product

The grades of NdFeB magnetic materials are: N35—N56, 35M—50M, 30H—48H, 30SH—45SH, 28UH—35UH, 28EH—35EH, N25AH-N35AH.

Grade example: indicates the sintered neodymium iron boron permanent magnet material with (BH)max of 366~398kj/m3 and Hcj of 800KA/m.


NdFeB surface treatment:

1. Phosphating;

2. Inorganic salt passivation;

3. Electroplating;

4. Electrophoresis;

5. Vacuum deposition;


application

Sintered NdFeB permanent magnet materials have excellent magnetic properties and are widely used in electronics, electrical machinery, medical equipment, toys, packaging, hardware machinery, aerospace and other fields. The more common ones are permanent magnet motors, speakers, magnetic separators, Computer disk drives, magnetic resonance imaging equipment meters, etc.


Curie temperature

The Curie temperature of ferrite is 465℃,

The Curie temperature of NdFeB is 320°C-460°C,

The Curie temperature of AlNiCo is 800℃,

The Curie temperature of samarium cobalt is 700-800℃

The Curie temperature of FeCrCo is 680 degrees


Process flow: ingredients → smelting ingot/belt spinning → powder making → profiling → sintering and tempering → magnetic inspection →Demagnetization curve

Grinding → pin cutting → electroplating → finished product. Among them, the ingredients are the basis, and the sintering and tempering is the key.

NdFeB magnet blank production tools and performance testing tools: smelting furnace, belt spinning furnace, jaw breaking machine, jet mill, compression molding machine, vacuum packaging machine, isostatic press, sintering furnace, heat treatment vacuum furnace, magnetic performance test Meter, Gauss meter.

NdFeB magnet machining tools: centerless grinding, spheronization machine, double-end grinding, flat grinding, slicer, double-sided grinding, wire cutting, bench drill, special-shaped grinding, etc.


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