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Zinc-based composite coating for improving corrosion resistance of neodymium-iron-boron magnet

A composite coating, corrosion-resistant technology, applied in coatings, devices for coating liquids on surfaces, anti-corrosion coatings, etc. Excellent weather resistance and chemical stability, small impact, improved corrosion resistance

Inactive Publication Date: 2012-09-05
BAOTOU RES INST OF RARE EARTHS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to improve the corrosion resistance of the surface of NdFeB magnets, to solve the problem that the electroplating of NdFeB magnets with Zn, Ni, Ni-Cu-Ni, Ni-P and epoxy plating is too thick to affect the performance of the magnets. The corner effect is obvious (especially for large-size magnets), the bonding force of the coating is not enough, the corrosion resistance is not ideal, and the pollution of the electroplating waste solution to the environment is serious. A zinc-based composite coating for NdFeB magnets is provided. layer and its preparation method, the zinc-based composite coating can not only greatly improve the surface corrosion resistance of the NdFeB magnet, but also prevent the pollution of the electroplating waste liquid to the environment

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] This embodiment is a sintered NdFeB magnet for a motor with a size of 56*25*4mm. The specific coating steps are as follows:

[0027] 1) Chamfering before coating: manual chamfering to R=0.3mm; degrease by soaking in a special alkaline degreasing agent at 40-50°C for about 10 minutes, and dry; perform shot blasting in a shot blasting machine, Ultrasonic cleaning.

[0028] 2) Zinc-based composite mother liquor (mainly composed of CrO 3 , polypropylene alcohol, polyethylene glycol, acrylic acid) and the base material (mainly composed of flake aluminum powder and zinc powder) are fully mixed at 20°C, and continuously stirred to prevent the base material from settling; use a spray gun to spray the treated magnet , the spray gun pressure is 0.4MPa, and the angle is 60°; start the spray filtration system to ensure that the solution is trapped in the pool of the rotating chamber, and control the leveling time for about 1 hour.

[0029] 3) After leveling, put the magnet into ...

Embodiment 2

[0035] The size of the sintered NdFeB magnet in this implementation is 4*4*2mm. The specific coating steps are as follows:

[0036] 1) Roll the magnet in a chamfering machine equipped with abrasives and chamfer it to R=0.1mm; soak it in alkaline degreasing solution at 40-50°C for about 15 minutes and dry it; Shot blasting, ultrasonic cleaning.

[0037] 2) Fully mix the chrome-free zinc-based composite coating solution at 20°C and continuously stir to prevent the base material from settling; put the treated magnet into the zinc-aluminum composite bath solution for dip coating for three minutes, and then perform centrifugal drying, generally 200 rpm, remove excess droplets.

[0038] 3) Put the magnet into the curing furnace to bake and cure, and keep warm at about 60°C for about 10 minutes as the furnace heats up. After that, continue to heat up to 300°C for 40 minutes with the furnace, and continue to heat for 10 minutes after power failure, open the furnace door, and leave ...

Embodiment 3

[0044] The size of the sintered NdFeB magnet in this implementation is 60*50*26mm. The specific coating steps are as follows:

[0045] 1) Roll the magnet in a chamfering machine equipped with abrasives and chamfer it to R=0.5mm; soak it in alkaline degreasing solution at 40-50°C for about 20 minutes and dry it; Shot blasting and ultrasonic cleaning after cooling.

[0046] 2) Zinc-based composite mother liquor (mainly composed of CrO 3 , polypropylene alcohol, polyethylene glycol, acrylic acid) and the base material (mainly composed of flake aluminum powder and zinc powder) are fully mixed at 20°C, and continuously stirred to prevent the base material from settling; use a spray gun to spray the treated magnet , the spray gun pressure is 0.4MPa, and the angle is 60°; start the spray filtration system to ensure that the solution is trapped in the pool of the rotating chamber, and control the leveling time for about 1 hour.

[0047] 3) After leveling, put the magnet into the cu...

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Abstract

The invention relates to a zinc-based composite coating for improving corrosion resistance of a neodymium-iron-boron magnet. The zinc-based composite coating is characterized by comprising a zinc-based coating and a reinforced protective coating, wherein the zinc-based coating consists of the following components by mass percent: 65%-95% of flake zinc powder, 1%-30% of flake aluminum powder and 0%-5% of amorphous composite chromic salt compound, the molecular formula of the amorphous composite chromic salt compound is nCrO3.mCr2O3, and n and m are natural numbers; and the reinforced protective coating is one of a wear-resisting organic silicone resin coating, a polytetrafluoroethylene coating and an epoxy resin coating. The zinc-based composite coating provided by the invention has the advantages that the coating is uniform and compact in structure and good in substrate bonding property, is not easy to peel or fall off, is less in magnetic property influence, uniform in thickness, low in porosity and extremely strong in corrosion resistance, is extremely compact and has no corner effect and no hydrogen embrittlement; and the process is environment-friendly.

Description

Technical field: [0001] The invention relates to the field of surface anticorrosion of NdFeB magnets, in particular to a zinc-based composite coating for improving the anticorrosion performance of NdFeB magnets, which functions to improve the surface corrosion resistance of NdFeB magnets. technical background: [0002] NdFeB magnets are a new generation of permanent magnet materials with the highest magnetic performance, the most widely used and the fastest development that have been produced industrially. One of the most important functional materials in the technical field. At present, my country has developed into the world's largest producer of NdFeB magnets. In 2008, the output of sintered NdFeB magnets in my country has accounted for about 80% of the total output of sintered NdFeB magnets in the world, with a total output value of 14-20 billion yuan, driving the output value of related applications to more than 100 billion yuan. [0003] NdFeB magnets generally work ...

Claims

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Application Information

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IPC IPC(8): C09D5/38C09D5/10B05D7/14H01F41/02
Inventor 陈蓓新邢正茂
Owner BAOTOU RES INST OF RARE EARTHS
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