Magnet surface treatment method

A surface treatment and magnet technology, applied in metal material coating process, superimposed layer plating, coating and other directions, can solve the problems of anti-corrosion effect not as good as hexavalent chromium passivation, environmental pollution, etc., achieve excellent anti-corrosion effect, combined with The effect of good strength and good anti-corrosion ability

Inactive Publication Date: 2015-03-18
BEIJING ZHONG KE SAN HUAN HI TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The traditional hexavalent chromium passivation has strong anti-corrosion ability, but it will cause serious environmental pollution
Chromium-free passivation can avoid pollution to the environment, but its anti-corrosion effect is far inferior to hexavalent chromium passivation

Method used

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  • Magnet surface treatment method
  • Magnet surface treatment method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] Take 20 pieces of sintered NdFeB permanent magnets (the brand is N35SH) with a size of 40mm×8mm×5mm. Chamfering R>0.2mm, after 240 mesh corundum blasting pressure 0.5 ~ 0.6Mpa pretreatment for 2min. Then vacuum ion evaporation coating is carried out, and the thickness of the coated film is 8-10 μm. Choose 10 pieces of them to conduct the Highly Accelerated Humidity and Heat Stress Test (HAST) (120°C, 2atm, saturated humidity), and observe after 160h that the magnets are intact, and there is no change such as peeling and blistering on the surface. Choose 10 of them for the neutral salt spray (NSS) test. After 72 hours, the magnet is intact and there is no red rust on the surface.

Embodiment 2

[0028] Take 20 pieces of sintered NdFeB permanent magnets (the brand is N35SH) with a size of 40mm×8mm×5mm. Chamfering R>0.2mm, vacuum ion evaporation coating after degreasing and rust removal, the thickness of the coating is 8-10μm. Choose 10 of them for HAST test (120℃, 2atm, saturated humidity), after 160 hours, the magnets are intact, and the surface has no changes such as peeling and blistering. Choose 10 of them for NSS test. After 72 hours, the magnet is intact and there is no red rust on the surface.

Embodiment 3

[0030] Take 20 pieces of sintered NdFeB permanent magnets (brand N33SH) with a size of 40mm×8mm×5mm. Chamfering R>0.2mm, vacuum ion evaporation coating after degreasing and rust removal, the thickness of the coating is 8-10μm, and then 3+ passivation treatment in the trivalent chromate passivation solution for 5 minutes, and let it air for 8 hours at room temperature. Choose 10 pieces from them for HAST test (120°C, 2atm, saturated humidity), observe after 200 hours, the magnet is intact, and there is no change such as peeling and blistering on the surface. In addition, 10 pieces were selected for NSS test. After 96 hours, the magnet was intact and there was no red rust on the surface.

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Abstract

The invention provides a magnet surface treatment method which comprises: a step of vacuum ion plating, and a step of passivation treatment of the plated film in a passivating solution containing trivalent chromate. When compared with a pure evaporation plating method, the vacuum ion evaporation plating method adopted by the invention has an additional ion source, and thus provides a high ionization rate for aluminium atoms. Aluminium ions are accelerated by a negative bias electric field, and are deposited on a product surface with a higher energy; thus a continuous plated layer without crystal boundaries is formed; the bonding force between the plated layer and the substrate is good; and better anticorrosion effect of the plated layer is achieved. In addition, according to the invention, the product subjected to vacuum ion evaporation aluminization is passivated by trivalent chromate, which provides the plated layer with very good anticorrosion performance, and prevents environment pollution.

Description

technical field [0001] The invention relates to a magnet surface treatment method. The magnet surface is coated with vacuum ion coating, and then the formed coating is subjected to passivation treatment in a passivation solution containing trivalent chromate. Background technique [0002] The structure of NdFeB magnets makes it easy to oxidize itself, so it is necessary to treat the surface of the magnets to improve the corrosion resistance of the magnets. The aluminized film on the surface of the NdFeB magnet not only has good anti-corrosion performance, no magnetic shielding effect, but also makes the product look beautiful. Chinese patent document CN102108510A discloses a composite protection process of vacuum aluminum plating and cathodic electrophoresis for NdFeB magnets and a NdFeB magnet with a composite protection layer. [0003] Although the vacuum magnetron sputtering method can produce a relatively dense aluminum layer, the film forming speed is slow and the prod...

Claims

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Application Information

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IPC IPC(8): C23C28/00C23C14/32C23C22/48
Inventor 王进东张纪功饶晓雷胡伯平
Owner BEIJING ZHONG KE SAN HUAN HI TECH
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