Method for improving oxidation resistance through normal-temperature blackening of rare earth permanent magnet powder

A technology with anti-oxidation properties and rare earth permanent magnets, applied in transportation and packaging, metal material coating technology, metal processing equipment, etc., can solve problems such as high reaction temperature, high energy consumption, and environmental pollution, and achieve high film forming efficiency , the effect of low energy consumption

Inactive Publication Date: 2018-06-29
ZHEJIANG UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the traditional bluing process uses sodium hydroxide as the reaction medium, and the reaction temperature is high, reaching 110-130°C. At the same time, the concentration of sodium hydroxide is high, reaching 200g/L, so a large amount of alkali mist is generated, which pollutes the environment; the generated oxidation The thickness of the film is not easy to control; since the main component of the formed oxide film is soft magnetic Fe3O4, if the rare earth permanent magnet powder adopts the traditional bluing process, the performance of the rare earth permanent magnet powder will be reduced and its magnetic properties will be affected; and in order to overcome the high temperature The problem of blackening, the normal temperature blackening technology with se

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] In this implementation case, a kind of rare earth permanent magnet powder normal temperature blackening treatment improves the method for oxidation resistance, comprises the steps:

[0024] (1). Preparation of bluing solution: Prepare a normal temperature blackening treatment solution in a beaker filled with 50ml of deionized water. The proportion of the solution is: copper sulfate pentahydrate 16 g / L, sodium gluconate 9 g / L, Sodium nitrite 5g / L, adjust the pH value of the solution to 6 with sodium hydroxide, then stir it evenly with a glass rod and pour it into a container with a capacity of 500ml;

[0025] (2). Add 10g of neodymium-iron-boron (Nd-Fe-B) magnetic powder with an average particle size of 75 microns to the liquid described in step (1), put it in a stirrer and stir continuously, start timing at the same time, and react for 10 minutes , to form a dense oxide film on the surface of Nd-Fe-B magnetic powder;

[0026] (3). After the reaction described in step (...

Embodiment 2

[0030] In this implementation case, a kind of rare earth permanent magnet powder normal temperature blackening treatment improves the method for oxidation resistance, comprises the steps:

[0031](1). Preparation of bluing solution: Prepare a normal temperature blackening treatment solution in a beaker filled with 50ml of deionized water. The proportion of the solution is: copper sulfate pentahydrate 10 g / L, copper nitrate 5 g / L, lemon Potassium acid 5 g / L, potassium sodium tartrate 6 g / L, sodium molybdate 5 g / L, adjust solution pH value to be 6 with sodium hydroxide, pour into the container that capacity is 500ml after stirring with glass rod then;

[0032] (2). Add 10g of the weighed neodymium-iron-boron (Nd-Fe-B) magnetic powder into the liquid described in step (1), put it into the stirrer and stir continuously, start timing at the same time, and react for 20 minutes to make A dense bluish film is formed on the surface of Nd-Fe-B magnetic powder;

[0033] (3). After the r...

Embodiment 3

[0037] In this implementation case, a kind of rare earth permanent magnet powder normal temperature blackening treatment improves the method for oxidation resistance, comprises the steps:

[0038] (1). Preparation of bluing solution: Prepare a normal temperature blackening treatment solution in a beaker filled with 50ml of deionized water. The proportion of the solution is: copper sulfate pentahydrate 13g / L, hydroxyethylidene diphosphonic acid 12 g / L L, potassium phosphate 5 g / L, adjust the pH value of the solution to 7 with sodium hydroxide, then pour it into a container with a capacity of 500ml after stirring evenly with a glass rod;

[0039] (2). Add 10g of samarium-iron-nitrogen (Sm-Fe-N) with an average particle size of 10 microns to the liquid described in step (1), put it in a stirrer and stir continuously, start timing at the same time, and react for 5 minutes , to form a thin and dense bluish film on the surface of samarium iron nitrogen (Sm-Fe-N);

[0040] (3). Afte...

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Abstract

The invention provides a method for improving oxidation resistance through normal-temperature blackening of rare earth permanent magnet powder. The method comprises the following steps: the rare earthpermanent magnet powder is dipped in normal-temperature blackening water treatment liquid, prepared by stated steps and containing divalent copper ions, a complexing agent and an oxidizing agent, forreplacement-oxidation reaction under normal temperature; different reaction times are controlled; and after the reaction is finished, magnetic powder is magnetically separated from reaction liquid bya permanent magnet for such steps as solid-liquid separation, distilled water washing, anhydrous ethanol extraction and 50-DEG C low-temperature drying to obtain the magnetic powder coated with a thin and compact oxide film on the surface. The method has the characteristics of simple process operation, low energy consumption, high film forming efficiency, environmental protection and the like; and the treated rare earth permanent magnet powder is more excellent in high-temperature oxidation resistance.

Description

technical field [0001] The invention relates to a method for coating the surface of a rare earth permanent magnet powder with an anti-oxidation layer by utilizing the technology of chemical blackening treatment, which belongs to the technology of powder surface treatment. Background technique [0002] Compared with ferrite, rare earth permanent magnet powders such as NdFeB, SmFeN, SmCo, etc. have a higher maximum magnetic energy product and are widely used. With the development of miniaturization and high power of household appliances, the composite rare earth permanent magnet material obtained by injection molding and extrusion processing of rare earth permanent magnet powder and polymer material has the advantages of simple production process, high product size accuracy, The advantages of good consistency are widely used in micro-motors. When injection molding is extruded, high temperature treatment is required, especially when polyphenylene sulfide is used as a polymer b...

Claims

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Application Information

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IPC IPC(8): C23C22/68C23C22/42C23C22/07C23C22/50B22F1/00
CPCC23C22/07C23C22/42C23C22/50C23C22/68B22F1/145
Inventor 郑精武胡敬显乔梁蔡伟姜力强车声雷李旺昌应耀余靓
Owner ZHEJIANG UNIV OF TECH
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