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Preparation method of corrosion-resistant double coatings of improved sintered Nd-Fe-B magnet

A technology of NdFeB and corrosion resistance, which is applied in the direction of coating, surface reaction electrolytic coating, metal material coating process, etc., can solve the problem of reducing the magnetic properties of magnets, limited effect, reducing the coercive force and magnetic energy product of magnets, etc. question

Active Publication Date: 2020-04-14
NANCHANG HANGKONG UNIVERSITY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The effect of alloying is relatively limited, and the addition of alloying elements will reduce the magnetic properties of the magnet to a certain extent, such as Co can form a stable grain boundary phase to improve corrosion resistance but reduce the coercive force and magnetic energy product of the magnet itself

Method used

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  • Preparation method of corrosion-resistant double coatings of improved sintered Nd-Fe-B magnet
  • Preparation method of corrosion-resistant double coatings of improved sintered Nd-Fe-B magnet
  • Preparation method of corrosion-resistant double coatings of improved sintered Nd-Fe-B magnet

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Embodiment 1

[0031] The invention provides a preparation method for improving the corrosion resistance of a sintered NdFeB magnet, comprising the following steps:

[0032] S1. Pickling, derusting and degreasing treatment: Put the sintered NdFeB magnet N35 into a nitric acid solution with a mass fraction of 5% for pickling for 30s to remove the rust and grease on the surface of the sintered NdFeB magnet;

[0033] S2. Micro-arc oxidation treatment: put the sintered NdFeB magnet after the pickling treatment in step S1 into the electrolyte prepared by sodium aluminate, sodium hypophosphite and deionized water for micro-arc oxidation treatment, wherein the sodium aluminate The concentration of sodium hypophosphite is 12.3g / L, and the concentration of sodium hypophosphite is 1g / L; the micro-arc oxidation treatment adopts a bidirectional pulsed micro-arc oxidation power supply, with neodymium iron boron as the positive pole and a stainless steel electrolytic cell as the negative pole, and controll...

Embodiment 2

[0042] The invention provides a method for preparing a double coating for improving the corrosion resistance of sintered NdFeB magnets, comprising the following steps:

[0043] S1. Pickling, derusting and degreasing treatment: Put the sintered NdFeB magnet N35 into a nitric acid solution with a mass fraction of 5% for pickling for 30s to remove the rust and grease on the surface of the sintered NdFeB magnet;

[0044]S2. Micro-arc oxidation treatment: put the sintered NdFeB magnet after the pickling treatment in step S1 into the electrolyte prepared by sodium aluminate, sodium hypophosphite and deionized water for micro-arc oxidation treatment, wherein the sodium aluminate The concentration of sodium hypophosphite is 12.3g / L, and the concentration of sodium hypophosphite is 1g / L; the micro-arc oxidation treatment adopts a bidirectional pulsed micro-arc oxidation power supply, with neodymium iron boron as the positive pole and a stainless steel electrolytic cell as the negative p...

Embodiment 3

[0051] The invention provides a preparation method for improving the corrosion resistance of a sintered NdFeB magnet, comprising the following steps:

[0052] S1. Pickling, derusting and degreasing treatment: put the sintered NdFeB magnet N35 into a nitric acid solution with a mass fraction of 4% for pickling for 35s to remove the rust and grease on the surface of the sintered NdFeB magnet;

[0053] S2. Micro-arc oxidation treatment: put the sintered NdFeB magnet after the pickling treatment in step S1 into the electrolyte prepared by sodium aluminate, sodium hypophosphite and deionized water for micro-arc oxidation treatment, wherein the sodium aluminate The concentration of sodium hypophosphite is 20g / L, and the concentration of sodium hypophosphite is 1.5g / L; the micro-arc oxidation treatment adopts a bidirectional pulse micro-arc oxidation power supply, with neodymium iron boron as the positive pole and a stainless steel electrolytic cell as the negative pole, and controlle...

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Abstract

The invention provides a preparation method of corrosion-resistant double coatings of an improved sintered Nd-Fe-B magnet. The preparation method comprises the steps of S1, conducting acid pickling, derusting and degreasing treatment, specifically, feeding the sintered Nd-Fe-B magnet into a nitric acid solution for acid pickling to remove rust and grease on the surface of the sintered Nd-Fe-B magnet; S2, conducting micro-arc oxidation treatment, specifically, feeding the sintered Nd-Fe-B magnet subjected to acid pickling into an electrolyte prepared from sodium aluminate, sodium hypophosphiteand deionized water for micro-arc oxidation treatment; S3, conducting spraying treatment, specifically, conducting spraying treatment on the sintered Nd-Fe-B magnet subjected to micro-arc oxidation treatment in the step S2 through a mixture comprising zinc oxide whiskers and polydimethyl siloxane; and S4, conducting natural drying, specifically, naturally drying the sintered Nd-Fe-B magnet subjected to spraying treatment in the step S3 in the environment and eventually forming a corrosion-resistant double-coating structure composed of the micro-arc oxidation ceramic coating and the zinc oxidewhisker / polydimethyl siloxane super-hydrophobic coating on the surface of the sintered Nd-Fe-B magnet.

Description

technical field [0001] The invention relates to the technical field of magnetic materials, in particular to a method for preparing a double coating for improving the corrosion resistance of sintered NdFeB magnets. Background technique [0002] Sintered NdFeB permanent magnets (NdFeB) have been widely used in wind power generation, new energy vehicles, energy-saving inverter air conditioners, energy-saving elevators, robots and intelligent manufacturing due to their excellent magnetic properties. However, there are a large number of pores and looseness on the surface of sintered NdFeB material, which is easy to oxidize and rust, and its chemical stability and corrosion resistance are poor; in addition, due to its own multi-phase structure, there is a large chemical potential difference between each phase, resulting in Nd-rich phase and boron-rich phase are preferentially decomposed, making the ferromagnetic main phase Nd 2 Fe14 B It is destroyed, which seriously deteriorate...

Claims

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Application Information

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IPC IPC(8): C25D11/34C23C26/00
CPCC23C26/00C25D11/026C25D11/34
Inventor 徐吉林陈金薛名山罗军明
Owner NANCHANG HANGKONG UNIVERSITY
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